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

Abstract

The present invention provides a moisture-curable polyurethane hot-melt resin composition including a urethane prepolymer (i) that has an isocyanate group and is a reaction product of a polyol (A) and a polyisocyanate (B), said moisture-curable polyurethane hot-melt resin composition characterized in that the polyol (A) includes polytetramethylene glycol or a polycarbonate polyol (a1) that is derived from biomass, a polyol (a2) that has an aromatic ring, and a polyester polyol (a3) that is different from (a2) and is solid at room temperature. Additionally, the present invention provides a manufacturing method for a synthetic leather that has at least a substrate, an adhesive layer, and a surface skin layer, said manufacturing method for a synthetic leather characterized in that the adhesive layer is obtained through said manufacturing method for a 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 technology]

[0002] As restrictions on the use of dimethylformamide (DMF) in Europe are coming into full swing, there is a strong demand for solvent-free, energy-saving, environmentally friendly resins. In this context, solvent-free moisture-curing hot-melt urethane compositions have attracted attention and are widely used in the manufacture of building materials, automotive interior materials, and electric and electronic devices such as refrigerators, smartphones, personal computers, and car navigation systems. In particular, in recent years, there have been an increasing number of cases in which moisture-curing polyurethane hot-melt compositions are foamed to produce foamed cured products for the purposes of improving impact resistance and texture through the cushioning effect, reducing the amount of moisture-curing hot-melt urethane composition used, and the like.

[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, there is a demand for a foamed sheet having a better texture.

[0004] On the other hand, as the recent marine plastic problem has drawn attention, bio-based resins that aim to move away from petroleum resources are attracting increasing attention day by day, and moisture-curing polyurethane resin compositions are no exception. However, it has been pointed out that increasing the biomass content can lead to a decrease in texture, etc., and achieving both of these properties has been a major challenge. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2004-115705 A [Patent Document 2] JP 2003-306526 A Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a method for producing a polyurethane foam sheet which has an increased biomass content by using a biomass raw material, excellent foam retention properties, and a good texture. [Means for solving the problem]

[0007] The present invention provides a method for producing a polyurethane foam sheet, comprising 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), applying the mixture obtained by the mixing to a substrate in the form of a sheet, and bringing the mixture into contact with water vapor to water-foam the mixture, wherein 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) ​​other than the (a2) that is solid at room temperature, and the polyol composition (Y) contains an amine catalyst (y1) having a foaming constant (Kw) of 10 or more.

[0008] The present invention also provides 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. Effect of the Invention

[0009] According to the method for producing a polyurethane foam sheet of the present invention, a polyurethane foam sheet having excellent foam retention and good texture can be obtained. The polyurethane foam sheet of the present invention is an environmentally friendly sheet having a high biomass content using a biomass raw material. In addition, the polyurethane foam sheet has excellent adhesiveness and can be particularly suitably used as an adhesive layer for synthetic leather. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The method for producing a polyurethane foam sheet of the present invention comprises 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), applying the mixture obtained in the form of a sheet onto a substrate, and bringing the sheet-like mixture into contact with water vapor to water-foam the mixture, and specific polyols (A) and polyol composition (Y) are used.

[0011] The urethane prepolymer (i) may be a reaction product of a specific polyol (A) and a polyisocyanate (B).

[0012] The polyol (A) contains, as essential components, biomass-derived polytetramethylene glycol or polycarbonate polyol (a1), 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 foam retention, texture, and adhesion.

[0013] The biomass-derived polytetramethylene glycol or polycarbonate polyol (a1) is an essential component for increasing the biomass content of the resin and for imparting basic physical properties such as excellent mechanical strength of the adhesive film.

[0014] As the biomass-derived polytetramethylene glycol, for example, "Bio PTMG" manufactured by Mitsubishi Chemical Corporation and the like can be obtained as a commercially available product.

[0015] As the biomass-derived polycarbonate polyol, polycarbonate polyols made from biomass-derived glycols having 1 to 10 carbon atoms, more preferably 3 to 10, can be used, and the like can be obtained as commercially available products, such as "Benebiol NL-2010DB" manufactured by Mitsubishi Chemical Corporation, "Benebiol NL-3010DB" manufactured by Mitsubishi Chemical Corporation, "Benebiol NL-2000D" manufactured by Mitsubishi Chemical Corporation, and "PCDX222" manufactured by Asahi Kasei Corporation. These polycarbonate polyols may be used alone or in combination of two or more kinds.

[0016] 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).

[0017] The amount of the biomass-derived polytetramethylene glycol or polycarbonate polyol (a1) used is preferably from 50 to 90% by mass, more preferably from 60 to 80% by mass, in the polyol (A).

[0018] The polyol (a2) having an aromatic ring provides the coating with excellent flexibility, texture, and adhesiveness, and examples of the polyol that can be used include polyether polyols having an aromatic ring and polyester polyols having an aromatic ring.

[0019] As the polyether polyol having an aromatic ring, for example, bisphenol A, bisphenol F, and their alkylene oxide adducts can be used. These polyols may be used alone or in combination of two or more. Among these, polyether polyols which are alkylene oxide adducts of bisphenol A are preferred. As the alkylene oxide, alkylene oxides having 2 to 8 carbon atoms are preferred, and the number of moles of the alkylene oxide added is preferably 2 to 10 moles, more preferably 4 to 8 moles.

[0020] As the polyester polyol having an aromatic ring, for example, a reaction product of a compound having a hydroxyl group and a polybasic acid shown below can be used.

[0021] Examples of the compound having a hydroxyl group include ethylene glycol, propylene glycol, 1,4-butanediol, pentanediol, 2,4-diethyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, hexanediol, neopentyl glycol, hexamethylene glycol, glycerin, trimethylolpropane, bisphenol A, bisphenol F, and alkylene oxide adducts thereof. Among these, it is preferable to use an alkylene oxide adduct of bisphenol A. Furthermore, the alkylene oxide is preferably an alkylene oxide having 2 to 8 carbon atoms, and the number of moles of the alkylene oxide added is preferably 2 to 10 moles, more preferably 4 to 8 moles.

[0022] Examples of the polybasic acid that can be used include adipic acid, glutaric acid, pimelic acid, suberic acid, dimer acid, sebacic acid, undecanedicarboxylic acid, hexahydroterephthalic acid, phthalic acid, phthalic anhydride, isophthalic acid, and terephthalic acid.

[0023] The number average molecular weight of the polyol (a2) having an aromatic ring is preferably 500 to 10,000, and 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).

[0024] The amount of the polyol (a2) having an aromatic ring used is preferably from 10 to 40% by mass, more preferably from 20 to 30% by mass, in the polyol (A).

[0025] The polyester polyol (a3) ​​other than the (a2) that is solid at room temperature is an essential component for fixing bubbles, suppressing penetration of the adhesive into the fabric, and expressing an excellent texture. The term "solid at room temperature" means that the polyester polyol does not exhibit flowability at 25°C.

[0026] The polyester polyol (a3) ​​is preferably at least one selected from the group consisting of polyester polyols (a3-1) made from diethylene glycol and sebacic acid, polyester polyols (a3-2) made from 1,3-propanediol and sebacic acid, polyester polyols (a3-3) made from diethylene glycol, neopentyl glycol, and phthalic acid, and polyester polyols (a3-4) made from diethylene glycol and phthalic acid.

[0027] Furthermore, the polyester polyol (a3) ​​is preferably a polyester polyol (a3-1) made from diethylene glycol and sebacic acid, and / or a polyester polyol (a3-2) made from 1,3-propanediol and sebacic acid, in terms of increasing the biomass content of the resin. Note that examples of biomass raw materials for the polyester polyol include biomass-derived sebacic acid ("Bio Seb" manufactured by Toyokuni Oil Co., Ltd.), biomass-derived 1,3-propanediol ("SUSTERRA Propanediol" manufactured by Dupont), and biomass-derived diethylene glycol ("Bio DEG" manufactured by India Glycols Ltd.), which are commercially available.

[0028] As the polyester polyol (a3), in terms of obtaining a more excellent texture, polyester polyol (a3-3) made from diethylene glycol, neopentyl glycol, and phthalic acid, and / or polyester polyol (a3-4) made from diethylene glycol and phthalic acid are preferred, and polyester polyol (a3-3) made from diethylene glycol, neopentyl glycol, and phthalic acid is particularly preferred. The diethylene glycol may be derived from petroleum or biomass, but it is preferable to use biomass-derived diethylene glycol in order to increase the biomass content.

[0029] The number average molecular weight of the polyester polyol (a3) ​​is preferably from 500 to 10,000, and more preferably from 800 to 5,000. The number average molecular weight of the polyester polyol (a3) ​​is a value measured by gel permeation chromatography (GPC).

[0030] The amount of the polyester polyol (a3) ​​used is preferably from 10 to 30% by mass, and more preferably from 10 to 20% by mass, in the polyol (A).

[0031] The polyol (A) essentially contains 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, and more preferably 50% by mass or more.

[0032] Examples of the other polyols include polyester polyols other than (a2) and (a3), polycarbonate polyols other than (a1), polyether polyols other than (a1), polybutadiene polyols, and polyacrylic polyols. These polyols may be used alone or in combination of two or more. These polyols may be used alone or in combination of two or more.

[0033] The number average molecular weight of the other polyols is, for example, 500 to 100,000. The number average molecular weight of the other polyols is a value measured by gel permeation chromatography (GPC).

[0034] As the polyisocyanate (B), for example, aromatic polyisocyanates such as polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, xylylene diisocyanate, phenylene diisocyanate, tolylene 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 may be used alone or in combination of two or more. Among these, aromatic polyisocyanates are preferred, and diphenylmethane diisocyanate is more preferred, in view of obtaining good adhesion, reactivity, and mechanical properties.

[0035] 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 conditions in which the isocyanate groups of the polyisocyanate (B) are in excess of the hydroxyl groups of the polyol (A).

[0036] In producing the urethane prepolymer (i), the equivalent ratio ([NCO / OH]) of the isocyanate groups in the polyisocyanate (B) to the hydroxyl groups in the polyol (A) is preferably 1.1 to 5.0, and more preferably 1.5 to 3.5, from the viewpoints of adhesion, texture, and mechanical strength.

[0037] The isocyanate group content (hereinafter abbreviated as "NCO%") of the urethane prepolymer (i) is preferably 1.1 to 5.0 mass%, more preferably 1.5 to 3.5 mass%, from the viewpoints of adhesion, texture, 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.

[0038] 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.

[0039] The other additives that can be used include, other than the polyol composition (Y) described later, for example, a silane coupling agent, a thixotropy imparting agent, an antioxidant, a plasticizer, a filler, a dye, a pigment, a wax, etc. These additives may be used alone or in combination of two or more kinds.

[0040] By mixing the polyol composition (Y) with the moisture-curable polyurethane hot-melt composition, the isocyanate groups of the urethane prepolymer (i) react with the polyol in the polyol composition (Y), thereby appropriately increasing the viscosity and fixing the bubbles in the polyurethane foam sheet when foamed with water. This can also contribute to the flexibility, mechanical strength, and durability of the resulting polyurethane foam sheet.

[0041] Examples of the polyol that can be used include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,2-dimethyl-1,3-propanediol, 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. These compounds may be used alone or in combination of two or more.

[0042] The content of the polyol in the polyol composition (Y) is preferably from 0.1 to 10.0% by mass, more preferably from 0.5 to 5.0% by mass.

[0043] In the present invention, in order to obtain an excellent texture, it is essential that the polyol composition (Y) contains an amine catalyst (y1) having a foaming constant (Kw) of at least 10. By using the specific amine catalyst (y1), the reaction between the isocyanate groups of the urethane prepolymer (i) and water during water foaming can be accelerated, large cells can be formed, and the temperature and humidity during water foaming can be set to milder conditions than before, thereby obtaining an excellent texture.

[0044] In the present invention, the foaming constant (Kw) of the amine catalyst (y1) is the catalytic activity constant (L 2 / (wq.mol·hr)), and specifically, JP2019-85513A, JP2009-14981A, etc. can be referenced.

[0045] Examples of the specific amine catalyst (y1) include N,N,N',N''-pentamethyldiethylenetriamine (PMDETA, Kw=159), N,N,N',N'',N''-pentamethylethylenepropylenetriamine (PMEPTA, Kw=21.5), N,N,N',N'',N ''-Pentamethyldipropylenetetraamine (PMDPTA, Kw = 11.6), 1,1,4,7,10,10-hexamethyltriethylenetetramine (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. can be used. These catalysts may be used alone or in combination of two or more.

[0046] As the amine catalyst (y1), in view of obtaining a more excellent texture, it is preferable to use 1,4-diazabicyclo[2.2.2]octane=triethylenediamine in combination with another amine catalyst. In this case, in view of obtaining a more excellent texture, the mass ratio is preferably 1 / 1 to 1 / 10, and more preferably 1 / 1 to 1 / 5.

[0047] The amount of the amine catalyst (y1) used is preferably from 1.0 to 20% by mass, more preferably from 1.0 to 10% by mass, in the polyol composition (Y).

[0048] The polyol composition (Y) may contain other additives in addition to the amine catalyst (y1). Examples of the other additives include catalysts other than the (y1), foam stabilizers, flame retardants, antistatic agents, fillers, conductive agents, moisture absorbents, inert gases, silane coupling agents, thixotropic agents, tackifiers, waxes, plasticizers, heat stabilizers, light stabilizers, pigments, and hydrolysis inhibitors, which may be used alone or in combination. These additives may be used alone or in combination of two or more.

[0049] The amount of the polyol composition (Y) used is preferably 1.0 to 50 parts by mass, and 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).

[0050] Next, the method for producing the polyurethane foam sheet of the present invention will be described.

[0051] The method for producing a polyurethane foam sheet of the present invention includes the steps of mixing the moisture-curable polyurethane hot-melt resin composition (X) that has been heated and melted at, for example, 70 to 150°C with the polyol composition (Y), applying the mixture obtained by the mixing in the form of a sheet onto a substrate, and bringing the sheet-like mixture into contact with water vapor to water-foam the mixture.

[0052] The moisture-curable polyurethane hot-melt resin composition (X) and the polyol composition (Y) can be mixed, for example, using a high-speed mixing head or a disper.

[0053] Examples of the method for applying the mixture in a sheet form onto a substrate such as release paper include methods using a roll coater, a spray coater, a T-die coater, a knife coater, etc. The thickness of the mixture applied in a sheet form is, for example, 50 to 500 μm.

[0054] The obtained sheet-like mixture is brought into contact with water vapor to cause water foaming. The technical term "water foaming" as used in the present invention means that the water contained in the water vapor is used as a foaming agent, and foaming occurs as a result of the reaction between the isocyanate groups in the urethane prepolymer (i) used in the present invention and the water, generating carbon dioxide gas.

[0055] The conditions for contacting with the water vapor include, for example, setting the ambient temperature of the surface of the sheet-like mixture to, for example, 20 to 120°C, preferably less than 80°C, and more preferably 20 to 35°C, setting the ambient humidity of the surface of the sheet-like mixture to, for example, 50% or more, preferably 60% or more and less than 95%, and more preferably 60 to 85%, and setting the humidification time to, for example, 0.5 seconds to 10 minutes.

[0056] In addition, the method of contacting with water vapor may be a method using a humidification chamber, a water vapor spraying device, or the like that can keep the conditions of the atmospheric temperature, atmospheric humidity, and humidification time of the surface of the mixture constant, and more preferably, a device that generates saturated water vapor is used because the water vapor is less likely to cool and turn into water droplets during circulation in the production line. In order to further improve the thickness accuracy of the polyurethane foam sheet, it is preferable to use a pressure belt press, nip rolls, flat press, or the like in combination after the humidification treatment.

[0057] After the contact with 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%, for example.

[0058] As described above, according to the method for producing a polyurethane foam sheet of the present invention, a polyurethane foam sheet having a good texture can be obtained. In addition, the polyurethane foam sheet has excellent adhesiveness and can be particularly suitably used as an adhesive layer for synthetic leather.

[0059] Next, the method for producing the synthetic leather of the present invention will be described.

[0060] The synthetic leather has at least a substrate, an adhesive layer, and a surface layer, and the adhesive layer can be obtained by the method for producing a polyurethane foam sheet.

[0061] Examples of the substrate that can be used include fiber substrates such as nonwoven fabrics, woven fabrics, knitted fabrics, etc. made of polyester fibers, polyethylene fibers, nylon fibers, acrylic fibers, polyurethane fibers, acetate fibers, rayon fibers, polylactic acid fibers, cotton, hemp, silk, wool, glass fibers, carbon fibers, and blends thereof; nonwoven fabrics impregnated with resins such as polyurethane resin; nonwoven fabrics further provided with a porous layer; resin substrates such as thermoplastic urethane (TPU), and genuine leather, split leather, etc.

[0062] Examples of materials that can be used to form the surface layer include water-based urethane resins, solvent-based urethane resins, solventless urethane resins, water-based acrylic resins, solvent-based acrylic resins, solventless acrylic resins, solvent-based silicone resins, water-based silicone resins, solventless silicone resins, vinyl chloride resins, thermoplastic polyurethane resins, thermoplastic polyester resins, thermoplastic amide resins, thermoplastic polyolefin resins, etc. These materials may be used alone or in combination of two or more.

[0063] The synthetic leather can be produced, for example, by mixing the moisture-curable polyurethane hot-melt resin composition (X) and the polyol composition (Y) to form a sheet-like mixture on a surface layer formed on release paper, contacting the sheet-like mixture with water vapor to foam the mixture as described above, and bonding the resulting foamed sheet to an adhesive layer and the substrate.

[0064] If necessary, a surface treatment layer (top coat layer) may be provided on the skin layer. EXAMPLES

[0065] The present invention will now be described in more detail with reference to examples.

[0066] [Synthesis Example 1] A four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet, and a reflux condenser was charged with 70 parts by mass of biomass-derived polytetramethylene glycol ("Bio PTMG" manufactured by Mitsubishi Chemical Corporation, 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 of 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 ("Bio DEG" manufactured by India Glycols Ltd.), number average molecular weight: 2,000), and dried under reduced pressure at 110°C to dehydrate the water content to 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 continued for 2 hours until the isocyanate group content became constant, thereby obtaining a urethane prepolymer (i-1) with an NCO% of 3.32% by mass and a biomass content of 60.2% by mass, which was used as a moisture-curable polyurethane hot-melt resin composition (X1).

[0067] [Synthesis Example 2] A four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser was charged with 70 parts by mass of biomass-derived polytetramethylene glycol ("Bio PTMG" manufactured by Mitsubishi Chemical Corporation, number average molecular weight: 2,000), 20 parts by mass of polyester polyol having an aromatic ring (a reaction product of 6 moles 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 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), and dried under reduced pressure at 110 ° C. to dehydrate the water content to 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 continued for 2 hours until the isocyanate group content became constant, thereby obtaining a urethane prepolymer (i-2) with an NCO% of 3.33% by mass and a biomass content of 65.4% by mass, which was used as a moisture-curable polyurethane hot-melt resin composition (X2).

[0068] [Synthesis Example 3] A four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet, and a reflux condenser was charged with 70 parts by mass of biomass-derived polytetramethylene glycol ("Bio PTMG" manufactured by Mitsubishi Chemical Corporation), 20 parts by mass of a polyester polyol having an aromatic ring (a reaction product of a 6-mol propylene oxide adduct of bisphenol A, isophthalic acid, and biomass-derived sebacic acid ("Bio Seb" manufactured by Toyokuni Oil Mills), 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 Propanediol" manufactured by Dupont) and biomass-derived sebacic acid ("Bio Seb" manufactured by Toyokuni Oil Mills), number average molecular weight: 2,000), and the mixture was dried under reduced pressure at 110°C to dehydrate the mixture until the moisture content was 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 continued for 2 hours until the isocyanate group content became constant, thereby obtaining a urethane prepolymer (i-3) with an NCO% of 3.33% by mass and a biomass content of 65.4% by mass, which was used as a moisture-curable polyurethane hot-melt resin composition (X3).

[0069] [Synthesis Example 4] A four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser was charged with 70 parts by mass of biomass-derived polytetramethylene glycol ("Bio PTMG" manufactured by Mitsubishi Chemical Corporation, number average molecular weight: 2,000), 20 parts by mass of polyester polyol having an aromatic ring (a reaction product of 6 moles 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 biomass-derived polyester polyol (a reaction product of biomass-derived diethylene glycol ("Bio DEG" manufactured by India Glycols), neopentyl glycol, and orthophthalic acid, number average molecular weight: 1,000), and dried under reduced pressure at 110 ° C. to dehydrate the water content to 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 continued for 2 hours until the isocyanate group content became constant, thereby obtaining a urethane prepolymer (i-4) with an NCO% of 3.39% by mass and a biomass content of 63.9% by mass, which was used as a moisture-curable polyurethane hot-melt resin composition (X4).

[0070] [Comparative Synthesis Example 1] A four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet and a reflux condenser was charged with 100 parts by mass of biomass-derived polytetramethylene glycol ("Bio PTMG" manufactured by Mitsubishi Chemical Corporation, number average molecular weight: 2,000), and dried under reduced pressure at 110 ° C. to dehydrate until the moisture content was 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 reaction was continued for 2 hours until the isocyanate group content became constant, thereby obtaining a urethane prepolymer (iR-1) with NCO%; 3.36% by mass and biomass degree; 80% by mass, which was used as a moisture-curable polyurethane hot melt resin composition (XR1).

[0071] [Comparative Synthesis Example 2] A four-neck flask equipped with a thermometer, a stirrer, an inert gas inlet, and a reflux condenser was charged with 70 parts by mass of biomass-derived polytetramethylene glycol ("Bio PTMG" manufactured by Mitsubishi Chemical Corporation, 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 Mills) and biomass-derived diethylene glycol ("Bio DEG" manufactured by India Glycols), number average molecular weight: 2,000), and dried under reduced pressure at 110°C to dehydrate until the moisture content was 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 reaction was carried out for 2 hours until the isocyanate group content became constant, thereby obtaining a urethane prepolymer (iR-2) with an NCO% of 3.36% by mass and a biomass content of 80% by mass, which was used as a moisture-curable polyurethane hot-melt resin composition (XR2).

[0072] [Comparative Synthesis Example 3] In a four-neck 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 Corporation, number average molecular weight: 2,000) and 30 parts by mass of aromatic ring-containing polyether polyol (polyether polyol, which is a 6-mol adduct of propylene oxide of bisphenol A, number average molecular weight: 508) were charged, and the mixture was dried under reduced pressure at 110 ° C. to dehydrate until the moisture content was 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) with NCO%; 3.36% by mass and biomass degree; 56% by mass, which was used as a moisture-curable polyurethane hot melt resin composition (XR3).

[0073] [Method for measuring number average molecular weight] The number average molecular weight of the polyols used in the synthesis examples and the like is a value measured by gel permeation chromatography (GPC) under the following conditions.

[0074] Measurement equipment: High-speed GPC equipment (Tosoh Corporation "HLC-8220GPC") Column: The following columns manufactured by Tosoh Corporation were used, connected in series. "TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 "TSKgel G2000" (7.8mmI.D. x 30cm) x 1 Detector: RI (differential refractometer) Column temperature: 40℃ Eluent: tetrahydrofuran (THF) Flow rate: 1.0mL / min Injection volume: 100 μL (sample concentration 0.4% by mass in tetrahydrofuran solution) Standard sample: A calibration curve was prepared using the following standard polystyrene.

[0075] (Standard polystyrene) "TSKgel Standard Polystyrene A-500" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene A-1000" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene A-2500" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene A-5000" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-4" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-10" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-20" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-40" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-80" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-128" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-288" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-550" manufactured by Tosoh Corporation

[0076] [Preparation Example 1] <How to prepare the skin film> A pigment (DILAC BLACK HS6001 (DIC Corporation)) and 0.3 parts by mass of a defoamer (EVONIK Corporation's "TEGO Foamex 800") were mixed with "HYDRAN WLS 230" (DIC Corporation), a water-based urethane resin for the surface layer of synthetic leather, and the mixture was applied to a release paper (LINTEC Corporation's "EV 130TPD") at a coating weight of 100 g / m using a comma coater. 2 After uniformly applying the coating so that the coating was wet, it was dried at 70°C for 2 minutes and then at 120°C for 2 minutes to prepare a skin film with a thickness of 30 µm.

[0077] [Example 1] <Method of manufacturing polyurethane foam sheet> The moisture-curable polyurethane hot melt resin composition (X1) obtained in Synthesis Example 1 was heated to 120°C and melted, and 100 parts by mass of the urethane prepolymer (i-1) was mixed with 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 part by mass of a silicone foam stabilizer ("SF-2962" manufactured by Dow Corning Corporation, hereinafter abbreviated as "SF2962") to prepare a resin. 3.3 parts by mass of the polyol composition was stirred and mixed in a Homo Disper at 6,000 rpm for 20 seconds, and then immediately applied to a release paper ("DK-100" manufactured by Lintec Corporation) using an applicator to a thickness of 200 μm. A 50 μm-thick polyethylene film was then laminated thereon, followed by humidification with water vapor for 1 minute in an atmosphere at 30°C and humidity of 80%, and then allowed to stand for 1 day in an environment at a temperature of 23°C and humidity of 65% to obtain a polyurethane foam sheet.

[0078] <Production of synthetic leather> The moisture-curable polyurethane hot melt resin composition (X1) obtained in Synthesis Example 1 was heated and melted to 120°C, and 100 parts by mass of urethane prepolymer (i-1) was mixed with 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 part by mass of a silicone foam stabilizer (manufactured by Dow Corning Corporation, "SF-2962", hereinafter abbreviated as "SF2962") to prepare a polyol composition of 3.3 parts by mass. The mixture was stirred and mixed at 6,000 rpm for 20 seconds in a homodisper, and immediately applied to the surface film in a thickness of 200 μm using an applicator. After laminating a rayon napped cloth, the mixture was humidified with water vapor for 1 minute in an atmosphere of 30°C and humidity of 80%, and left for 1 day in an environment of temperature 23°C and humidity 65% ​​to obtain a synthetic leather.

[0079] [Example 2] A polyurethane foam sheet and synthetic leather were obtained in the same manner as in Example 1, except that the type of moisture-curable polyurethane hot-melt resin composition (X1) was changed to the moisture-curable polyurethane hot-melt resin composition (X2).

[0080] [Example 3] A polyurethane foam sheet and synthetic leather were obtained in the same manner as in Example 1, except that the type of moisture-curable polyurethane hot-melt resin composition (X1) was changed to the moisture-curable polyurethane hot-melt resin composition (X3).

[0081] [Example 4] A polyurethane foam sheet and synthetic leather were obtained in the same manner as in Example 1, except that the type of moisture-curable polyurethane hot-melt resin composition (X1) was changed to the moisture-curable polyurethane hot-melt resin composition (X4).

[0082] [Example 5] 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.

[0083] [Example 6] 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.

[0084] [Comparative Example 1] <Method of manufacturing polyurethane foam sheet> The moisture-curable polyurethane hot melt resin composition (XR1) obtained in Comparative Synthesis Example 1 was heated and melted at 120 ° C., and 100 parts by mass of the urethane prepolymer (iR-1) was mixed with 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 to prepare a polyol composition. The mixture was stirred and mixed at 6,000 rpm for 20 seconds using a homodisper, and then immediately applied to a release paper ("DK-100" manufactured by Lintec Corporation) with a thickness of 200 μm using an applicator. After laminating a 50 μm-thick polyethylene film, the mixture was humidified with water vapor for 1 minute in an atmosphere of 30 ° C. and 80% humidity, and left for 1 day in an environment of 23 ° C. and 65% humidity to obtain a polyurethane foam sheet.

[0085] <Production of synthetic leather> The moisture-curable polyurethane hot melt resin composition (XR1) obtained in Comparative Synthesis Example 1 was heated and melted to 120°C, and 100 parts by mass of urethane prepolymer (iR-1) was mixed with 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 to prepare a polyol composition. The mixture was stirred and mixed in a homodisper at 6,000 rpm for 20 seconds, and then immediately applied to the surface film to a thickness of 200 μm using an applicator. After laminating a rayon napped cloth, the mixture was humidified with water vapor for 1 minute in an atmosphere of 30°C and humidity of 80%, and left for 1 day in an environment of temperature 23°C and humidity 65% ​​to obtain a synthetic leather.

[0086] [Comparative Example 2] A polyurethane foam sheet and synthetic leather were obtained in the same manner as in Comparative Example 1, except that the type of moisture-curable polyurethane hot-melt resin composition (XR1) was changed to the moisture-curable polyurethane hot-melt resin composition (XR2).

[0087] [Comparative Example 3] <Method of manufacturing polyurethane foam sheet> The moisture-curable polyurethane hot-melt resin composition (XR3) obtained in Comparative Synthesis Example 3 was heated and melted at 120°C, and then immediately applied to a release paper ("DK-100" manufactured by Lintec Corporation) using an applicator to a thickness of 200 μm. A polyethylene film having a thickness of 50 μm was then laminated thereon. The composition was then humidified with water vapor for 1 minute in an atmosphere of 30°C and humidity 80%, and allowed to stand for 1 day in an environment of 23°C and humidity 65%, to obtain a polyurethane foam sheet.

[0088] <Production of synthetic leather> The moisture-curable polyurethane hot-melt resin composition (XR3) obtained in Comparative Synthesis Example 3 was heated to melt at 120°C and then immediately applied to the surface film to a thickness of 200 µm using an applicator. A rayon napped cloth was then attached, and the resultant was humidified with water vapor for 1 minute in an atmosphere of 30°C and humidity 80%, and left to stand for 1 day in an environment of temperature 23°C and humidity 65% ​​to obtain synthetic leather.

[0089] [Method for evaluating foam retention] After humidification and curing, each of the polyurethane foam sheets obtained in the Examples and Comparative Examples was left for 30 minutes at an atmospheric temperature of 23° C. and a relative humidity of 65%, and then a load of 1 kg was applied to an area of ​​5 cm×5 cm for 2 hours. After the load was removed, the foam collapse resistance against the stress was visually evaluated as follows: A: The foam bubbles are maintained and there is no change in appearance. B: The foam has been partially crushed, causing a change in appearance. C: The foam is completely crushed and its appearance has changed.

[0090] [How to evaluate texture] The synthetic leathers obtained in the Examples and Comparative Examples were evaluated for flexibility when folded by hand as follows. "1": Flexible. "2"; a little hard. "3"; hard.

[0091] [Table 1]

[0092] [Table 2]

[0093] In all of Examples 1 to 6, which are the production methods of the present invention, polyurethane foam sheets having a high biomass content, excellent foam retention properties, and excellent texture were obtained.

[0094] On the other hand, Comparative Examples 1 and 2, which are both embodiments using a polyol (A) and a polyol composition (Y) other than those specified in the present invention, were poor in foam retention and feel.

[0095] Comparative Example 3 was an embodiment in which a polyol (A) other than those specified in the present invention was used and no polyol composition (Y) was used, and the foam retention and feel were significantly poor.

Claims

1. A method for producing a polyurethane foam sheet, comprising: 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), applying the mixture obtained by mixing the mixture in a sheet form onto a substrate, and contacting the sheet-like mixture with water vapor to water-foam the mixture, The polyol (A) is Biomass-derived polytetramethylene glycol or polycarbonate polyol (a1); A polyol (a2) having an aromatic ring, and (a3) a polyester polyol other than the (a2) that is solid at room temperature; Contains the polyester polyol (a3) ​​is at least one selected from the group consisting of polyester polyols (a3-1) made from diethylene glycol and sebacic acid, polyester polyols (a3-2) made from 1,3-propanediol and sebacic acid, polyester polyols (a3-3) made from diethylene glycol, neopentyl glycol, and phthalic acid, and polyester polyols (a3-4) made from diethylene glycol and phthalic acid; The method for producing a polyurethane foam sheet, wherein the polyol composition (Y) contains an amine catalyst (y1) having a foaming constant (Kw) of 10 or more.

2. 2. The method for producing a polyurethane foam sheet according to claim 1, wherein the amine catalyst (y1) is a combination of 1,4-diazabicyclo[2.2.2]octane=triethylenediamine and another amine catalyst.

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

4. 2. 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 produced from an alkylene oxide adduct of bisphenol A.

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

6. 2. 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 according to claim 1.

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