Method for producing laminate, and method for producing synthetic leather

Abstract

The present invention provides a method for producing a laminate comprising a base material (i) and a urethane foam layer (ii). The method comprises: a step for applying a urethane foam layer-forming material onto a release paper sheet to form the urethane foam layer (ii); a step for bonding the base material (i) onto the urethane foam layer (ii) by a wet lamination method; and a step for peeling off the release paper sheet. The method is characterized in that: the urethane foam layer (ii) is in direct contact with the base material (i); the urethane foam layer-forming material contains a urethane resin (A) having a nonionic group; and the flow initiation temperature of the urethane resin (A) is higher than 130°C. A laminate produced by this production method exhibits good workability while having immediate peelability and soft texture.

Description

Method for manufacturing laminate and method for manufacturing synthetic leather

[0001] The present invention relates to a method for producing a laminate and a method for producing synthetic leather.

[0002] Due to their excellent mechanical strength and texture, urethane resins are widely used in the production of synthetic leathers, including artificial leathers. Until now, solvent-based urethane resins containing N,N-dimethylformamide (DMF) have been the mainstream for synthetic leather applications. However, due to DMF restrictions in Europe, strengthened VOC emission regulations in China and Taiwan, and DMF restrictions imposed by major apparel manufacturers, there is a demand for DMF-free urethane resin compositions for each layer of synthetic leather. Among these, water-based urethanes (PUDs), in which urethane resins are dispersed in water, are being considered as an alternative raw material for the intermediate porous layer formed by wet coagulation of conventional solvent-based urethane resins.

[0003] For example, Patent Document 1 discloses a foam-forming composition characterized by containing (A) a first self-emulsifying aqueous polyurethane resin having at least one hydrophilic functional group selected from the group consisting of a sulfo group and a sulfonate group, (B) a second self-emulsifying aqueous polyurethane resin having at least one hydrophilic functional group selected from the group consisting of a carboxy group and a carboxylate group, (C) a crosslinking agent, (D) a foaming agent, (E) a thickener, and (F) water, and a leather material having a foamed resin layer made of a foamed and cured product of the foam-forming composition.

[0004] However, conventional synthetic leathers such as those described in Patent Document 1 require an adhesive layer between the substrate and the urethane foam layer, which necessitates a relatively long period of aging, resulting in productivity problems.

[0005] Furthermore, in recent years, there has been a demand for synthetic leather that has a soft feel while also offering good processability, such as making the uneven patterns on the surface of the synthetic leather more clearly visible when embossed. However, there has been no synthetic leather that satisfies these increasingly increasing requirements, and there has been no synthetic leather that satisfies current market demands.

[0006] Therefore, there has been a demand for a laminate that is easy to peel, has a soft texture, and is also easy to process, and for a synthetic leather having such a laminate.

[0007] Japanese Patent Application Laid-Open No. 2020-109152

[0008] An object of the present invention is to provide a laminate that has quick peelability, a soft texture, and good processability, and to provide a synthetic leather having the laminate.

[0009] As a result of intensive research aimed at solving the above-mentioned problems, the present inventors have found that by using a urethane resin having a specific structure and exceeding a specific flow initiation temperature, and by forming a structure in which a substrate (i) and a urethane foam layer (ii) are in direct contact with each other by a wet lamination method, it is possible to prepare a laminate that has easy peelability, a soft texture, and good processability, and have completed the present invention.

[0010] That is, the present invention relates to a method for producing a laminate comprising a substrate (i) and a urethane foam layer (ii), the method comprising the steps of applying a urethane foam layer-forming material onto a release paper to form the urethane foam layer (ii), bonding the substrate (i) onto the urethane foam layer (ii) by a wet lamination method, and peeling off the release paper, wherein the urethane foam layer (ii) is in direct contact with the substrate (i), the urethane foam layer-forming material contains a urethane resin (A) having a nonionic group, and the urethane resin (A) has a flow initiation temperature of above 130°C.

[0011] According to the present invention, it is possible to provide a laminate that has quick peelability, a soft texture, and good processability, and a synthetic leather having the laminate.

[0012] The method for producing a laminate of the present invention includes the steps of applying a urethane foam layer-forming material onto a release liner to form a urethane foam layer (ii), bonding the substrate (i) onto the urethane foam layer (ii) by wet lamination, and peeling off the release liner, and is characterized in that the urethane foam layer (ii) is in direct contact with the substrate (i). That is, the laminate obtained by the production method of the present invention is characterized in that no adhesive layer is present between the substrate (i) and the urethane foam layer (ii).

[0013] <Substrate (i)> Examples of the substrate (i) that can be used include fiber substrates such as nonwoven fabrics, woven fabrics, and knitted fabrics made from 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 resins; nonwoven fabrics further provided with a porous layer; and resin substrates such as thermoplastic urethane (TPU).

[0014] <Urethane foam layer (ii)> The dry density of the urethane foam layer (ii) is 200 to 1000 kg / m ３ In the present invention, the dry density of the urethane foam layer (ii) is the weight of the laminate per 10 cm square minus the weight of the base material (i) per 10 cm square divided by the thickness of the urethane foam layer (ii).

[0015] The dry density of the urethane foam layer (ii) can be controlled by the expansion ratio, which can be controlled by the type of urethane used and the stirring speed and time during foaming.

[0016] The thickness of the urethane foam layer (ii) is, for example, 50 to 600 μm.

[0017] The urethane foam layer-forming material contains a urethane resin (A) having a nonionic group (hereinafter, sometimes referred to as "component (A)").

[0018] <<Urethane Resin (A) Having Nonionic Groups>> Component (A) is a urethane resin having nonionic groups and is dispersible in water. Component (A) has superior hydrolysis properties compared to other water-dispersible urethane resins (e.g., anionic urethane resins). Furthermore, since no crosslinking agent needs to be added, it has excellent processability.

[0019] The flow initiation temperature of component (A) is greater than 130° C., preferably greater than 150° C., and more preferably greater than 160° C. When the flow initiation temperature of component (A) is greater than 130° C., the peel strength is improved. Furthermore, when the flow initiation temperature of component (A) is equal to or greater than the above-mentioned preferable lower limit, the peel strength is further improved.

[0020] There is no particular upper limit to the flow temperature of component (A), but it is preferably 250°C or lower, for example.

[0021] The flow initiation temperature of component (A) can be controlled, for example, by appropriately adjusting the length of the molecular chain of the urethane resin. Specifically, it can be controlled by the amount of chain extender (a3) ​​added in the "chain extension step" described below.

[0022] The flow initiation temperature of the component (A) can be controlled, for example, by the type of polyol (a2), which is a raw material of the urethane resin (A) described below, the amount of chain extender (a2-1) used, and the type of polyisocyanate (a1).

[0023] Methods for adjusting the flow initiation temperature of component (A) to be high include, for example, using a polyol with high crystallinity such as a polycarbonate polyol as the polyol (a2), increasing the amount of chain extender (a2-1) used, and using a polyisocyanate with high crystallinity such as 4,4'-diphenylmethane diisocyanate or dicyclohexylmethane diisocyanate as the polyisocyanate (a1).

[0024] Methods for adjusting the flow initiation temperature of component (A) to a low level include using a polyol with low crystallinity such as polyoxypropylene glycol as the polyol (a2), reducing the amount of chain extender (a2-1) used, and using a polyisocyanate with low crystallinity such as toluene diisocyanate or isophorone diisocyanate as the polyisocyanate (a1).

[0025] In the present invention, the flow initiation temperature of component (A) is a value measured by applying the urethane resin composition to release paper (coating thickness: 150 μm), drying in a hot air dryer at 70°C for 4 minutes and then at 120°C for 2 minutes to obtain a dried product, and then measuring this dried product using a flow tester "CFT-500A" manufactured by Shimadzu Corporation (using a die with an aperture diameter of 1 mm and a length of 1 mm, a load of 98 N, and a temperature rise rate of 3°C / min).

[0026] Specific examples of the component (A) include urethane resins made from polyisocyanate (a1) and polyol (a2).

[0027] [Polyisocyanate (a1)] Examples of the polyisocyanate (a1) include aromatic polyisocyanates such as phenylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, polymethylene polyphenyl polyisocyanate, and carbodiimidized diphenylmethane polyisocyanate; and aliphatic or alicyclic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, dimer acid diisocyanate, and norbornene diisocyanate. These polyisocyanates can be used alone or in combination of two or more.

[0028] The proportion of the polyisocyanate (a1) used is preferably 5 to 60 mass%, more preferably 10 to 55 mass%, and even more preferably 15 to 50 mass%, relative to 100 mass% of the total of the polyisocyanate (a1) and the polyol (a2).

[0029] [Polyol (a2)] Examples of the polyol (a2) include polyether polyols, polyester polyols, polyacrylic polyols, polycarbonate polyols, polybutadiene polyols, etc. These polyols can be used alone or in combination of two or more.

[0030] From the viewpoint of the mechanical strength of the resulting coating, the number average molecular weight of the polyol (a2) is preferably 500 to 100,000, and more preferably 800 to 10,000. In the present invention, the number average molecular weight of the polyol (a2) is a value measured by gel permeation column chromatography (GPC).

[0031] Of the above, the polyol (a2) is preferably a polyether polyol (a21), a polycarbonate polyol (a22), or a polyester polyol (a23).

[0032] Polyether polyol (a21) Examples of the polyether polyol (a21) include polyethylene glycol, polypropylene glycol, polyethylene glycol-polytetramethylene glycol (block or random), polytetramethylene ether glycol, polyhexamethylene glycol, etc. Among these, polytetramethylene ether glycol is preferred.

[0033] Polycarbonate Polyol (a22) Commercially available polycarbonate polyol (a22) includes, for example, "ETERNACOLL UH-100" (manufactured by Ube Industries, Ltd.).

[0034] Examples of the polyester polyol (a23) include an esterification reaction product of a low-molecular-weight polyol with a polycarboxylic acid, a ring-opening polymerization product of a cyclic ester compound such as ε-caprolactone, and a polyester copolymer of the above-mentioned esterification reaction product or ring-opening polymerization product. Among these, a ring-opening polymerization product of a cyclic ester compound such as ε-caprolactone is preferred.

[0035] The proportion of polyol (a2) used is preferably 40 to 95 mass%, more preferably 45 to 90 mass%, and even more preferably 50 to 85 mass%, relative to 100 mass% of the total of polyisocyanate (a1) and polyol (a2), from the viewpoint of obtaining even better mechanical strength.

[0036] The component (A) may be a urethane resin made from polyisocyanate (a1), polyol (a2), chain extender (a3), and compound (a4) having an oxyethylene structure (excluding compounds corresponding to the above-mentioned (a1) to (a3)).

[0037] [Chain extender (a3)] As the chain extender (a3), a compound having a molecular weight of less than 500 (preferably in the range of 50 to 450) can be used, and specific examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, hexamethylene glycol, sucrose, methylene glycol, glycerin, sorbitol, bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, and trimethylol. Examples of suitable chain extenders include chain extenders having a hydroxyl group such as propane; and chain extenders having an amino group (-NH2, -NH-, -N(-)-), such as ethylenediamine, 1,2-propanediamine, 1,6-hexamethylenediamine, piperazine, 2,5-dimethylpiperazine, isophoronediamine, 1,2-cyclohexanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 4,4'-dicyclohexylmethanediamine, 3,3'-dimethyl-4,4'-dicyclohexylmethanediamine, 1,4-cyclohexanediamine, and hydrazine. These chain extenders can be used alone or in combination of two or more. In the present invention, the molecular weight of the chain extender (a3) ​​is the value calculated from the chemical formula.

[0038] As the chain extender (a3), a chain extender having an amino group (hereinafter also referred to as an "amine chain extender") is preferred because it can easily extend the chain even at relatively low temperatures of 30°C or less, thereby reducing energy consumption during the reaction, because the introduction of a urea group provides even better texture and peel strength, and because it further facilitates high solids content of component (A), and it is more preferable to use an amine chain extender with a molecular weight in the range of 30 to 250. When two or more types of chain extender (a3) ​​are used in combination, the average molecular weight of each chain extender (a3) ​​is indicated, and this average value may be within the preferred molecular weight range.

[0039] The proportion of chain extender (a3) ​​used is preferably 0.1 to 30 mass%, and more preferably 0.5 to 10 mass%, of the total mass of the raw materials constituting component (A), from the viewpoints of obtaining even better texture and peel strength and making it easier to achieve high solids content of component (A).

[0040] [Compound (a4) Having an Oxyethylene Structure] As the compound (a4) having an oxyethylene structure, for example, polyether polyols having an oxyethylene structure such as polyethylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxytetramethylene glycol, polyethylene glycol dimethyl ether, etc. can be used. These compounds can be used alone or in combination of two or more. Among these, it is preferable to use polyethylene glycol and / or polyethylene glycol dimethyl ether, since hydrophilicity can be controlled more easily.

[0041] The proportion of the compound (a4) having an oxyethylene structure used is preferably 0.1 to 10 mass%, more preferably 0.2 to 10 mass%, and even more preferably 0.25 to 8 mass%, of the total mass of the raw materials constituting the component (A), from the viewpoint of obtaining even better mechanical strength.

[0042] The component (A) can be used alone or in combination of two or more types.

[0043] The content of the component (A) is preferably 60 to 99 mass %, more preferably 65 to 98 mass %, and even more preferably 68 to 97 mass %, based on the total amount of solids constituting the urethane foam layer (ii).

[0044] [Method for producing urethane resin (A) having nonionic groups] The method for producing component (A) is not particularly limited, but examples include a method comprising a step of reacting polyisocyanate (a1), polyol (a2), and a compound (a4) having an oxyethylene structure in the absence of a solvent to obtain a urethane prepolymer (i) having an isocyanate group (hereinafter also referred to as the "prepolymer step"), subsequently dispersing the urethane prepolymer (i) in water (hereinafter also referred to as the "emulsification step"), and then reacting the urethane prepolymer (i) dispersed in water with a chain extender (a3) ​​to obtain a urethane resin (A) having a nonionic group (hereinafter also referred to as the "chain extension step").

[0045] "Prepolymerization Process" The prepolymerization process is preferably carried out in the absence of a solvent. In conventional technology, the prepolymerization process has generally been carried out in an organic solvent such as methyl ethyl ketone or acetone, but a desolvation process for distilling off the organic solvent is required after the emulsification process, which requires several production days in actual production sites. In addition, it is difficult to completely distill off the organic solvent in the desolvation process, and in many cases, a small amount of organic solvent remains, making it difficult to fully comply with environmental requirements. On the other hand, by producing a prepolymer in the absence of a solvent, a urethane resin completely free of organic solvent can be obtained, and the production process can also be made more labor-efficient.

[0046] In the prepolymerization step, the molar ratio of the sum of the hydroxyl groups in the polyol (a2) and the hydroxyl groups and amino groups in the compound (a4) having an oxyethylene structure to the isocyanate groups in the polyisocyanate (a1) [isocyanate groups / (hydroxyl groups and amino groups)] is preferably in the range of 1.1 to 3, more preferably in the range of 1.2 to 2, in order to obtain even better texture and peel strength.

[0047] The reaction in the prepolymerization step is carried out, for example, at 50 to 120° C. for 1 to 10 hours.

[0048] "Emulsification step" The emulsification step can be carried out using, for example, a reaction vessel equipped with an agitating blade; a kneader such as a kneader, a continuous kneader, a taper roll, a single-screw extruder, a twin-screw extruder, a triple-screw extruder, a universal mixer, a Plastomill, or a Bodeda-type kneader; a rotary dispersion mixer such as a homomixer, a static mixer, FILMICS, an Ebara Milder, a Clearmix, an Ultra-Turrax, a Cavitron, or a Biomixer; an ultrasonic dispersion device; or a device that has no moving parts and can mix by the flow of the fluid itself, such as an in-line mixer.

[0049] The water used in the emulsification step may be ion-exchanged water, distilled water, etc. These waters may be used alone or in combination of two or more kinds.

[0050] The emulsification step is preferably carried out at a temperature at which water does not evaporate, for example, in the range of 10 to 90°C. The emulsification step can be carried out using the same equipment as in the prepolymer step.

[0051] "Chain extension step" The chain extension step is a step of increasing the molecular weight of the urethane prepolymer (i) by reacting the isocyanate groups of the urethane prepolymer (i) with the chain extender (a3) ​​to obtain component (A). From the viewpoint of productivity, the chain extension step is preferably carried out at a temperature of 50°C or less.

[0052] In the chain extension step, the molar ratio of the isocyanate groups in the urethane prepolymer (i) to the sum of the hydroxyl groups and amino groups in the chain extender (a3) ​​[(hydroxyl groups and amino groups) / isocyanate groups] is preferably in the range of 0.8 to 1.1, more preferably in the range of 0.9 to 1, in order to obtain even better texture and peel strength.

[0053] <<Optional Components>> The urethane foam layer (ii) may contain optional components other than the component (A).

[0054] Examples of the optional components include surfactants, thickeners, leveling agents, pigments, antifoaming agents, crosslinking agents, emulsifiers, neutralizing agents, film-forming aids, urethanization catalysts, fillers, dyes, flame retardants, antiblocking agents, etc. These optional components can be used alone or in combination of two or more.

[0055] It is preferable that component (A) is produced substantially without organic solvent, but an organic solvent may be added as an additive.

[0056] In addition, the urethane foam layer (ii) preferably does not contain a crosslinking agent.

[0057] The urethane foam layer (ii) preferably contains the component (A), a surfactant, and a thickener.

[0058] [Surfactant] The surfactant is preferably a surfactant having a hydrophobic moiety with 10 or more carbon atoms.

[0059] Specifically, the surfactant is preferably a long-chain carboxylate, more preferably a long-chain carboxylate having 10 to 20 carbon atoms, and even more preferably a long-chain carboxylate having 14 to 20 carbon atoms.

[0060] Examples of surfactants include alkali metal salts of long-chain carboxylic acids, amine salts of long-chain carboxylic acids, and ammonium salts of long-chain carboxylic acids.

[0061] As the alkali metal used as a raw material for the alkali metal salt of a long-chain carboxylic acid, sodium and potassium are preferred.

[0062] Examples of amines used as raw materials for the long-chain carboxylic acid amine salt include monoamines, alkanolamines, and polyamines.

[0063] Examples of the monoamine include primary amines, secondary amines, and tertiary amines.

[0064] Examples of primary amines include ethylamine, n-propylamine, butylamine, 1-ethylbutylamine, 1,3-diaminopropane, and cyclohexylamine.

[0065] Examples of secondary amines include diethylamine, di-n-propylamine, di-n-butylamine, 4,4'-diaminodiphenylamine, diethylenetriamine, tetraethylenepentamine, N-(2-aminoethyl)ethanolamine, and morpholine.

[0066] Examples of tertiary amines include dimethylethylamine, diethylmethylamine, triethylamine, and tributylamine.

[0067] Examples of alkanolamines include monoethanolamine, diethanolamine, triethanolamine, diethylethanolamine, and propanolamine.

[0068] Examples of polyamines include alkylene polyamines such as ethylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine, propylene diamine, dipropylene triamine, tripropylene tetramine, tetrapropylene pentamine, pentapropylene hexamine, butylene diamine, dibutylene triamine, tributylene tetramine, tetrabutylene pentamine, and pentabtylene hexamine; N-alkyl ethylene diamines such as N-methyl ethylene diamine, N-ethyl ethylene diamine, and N-propyl ethylene diamine; N-alkenyl ethylene diamines such as N-vinyl ethylene diamine, N-propenyl ethylene diamine, and N-butenyl ethylene diamine; and N-alkyl or N-alkenyl alkylene polyamines such as N-alkyl diethylene triamine, N-alkenyl diethylene triamine, and N-alkyl triethylene tetramine.

[0069] Of the surfactants listed above, ammonium salts of long-chain carboxylic acids having 10 to 20 carbon atoms are preferred, ammonium salts of long-chain carboxylic acids having 14 to 20 carbon atoms are more preferred, and ammonium stearate is even more preferred.

[0070] The surfactants can be used alone or in combination of two or more kinds.

[0071] The content of the surfactant is preferably 0.01 to 30% by mass, more preferably 0.1 to 20% by mass, and even more preferably 1 to 10% by mass, based on the total amount of solids constituting the urethane foam layer (ii).

[0072] [Thickener] Examples of thickeners include cellulose thickeners; acrylic thickeners; urethane thickeners; protein thickeners such as casein, sodium caseinate, and ammonium caseinate; polyvinyl thickeners such as polyvinyl alcohol, polyvinylpyrrolidone, and polyvinylbenzyl ether copolymers; polyether thickeners such as Pluronic (registered trademark) polyether, polyether dialkyl esters, polyether dialkyl ethers, and polyether epoxy-modified products; maleic anhydride thickeners such as vinyl methyl ether-maleic anhydride copolymers; and polyamide thickeners such as polyamidoamine salts.

[0073] The thickeners can be used alone or in combination of two or more kinds.

[0074] The content of the thickener is preferably 0.01 to 10% by mass, more preferably 0.05 to 8% by mass, and even more preferably 0.1 to 5% by mass, based on the total amount of solids constituting the urethane foam layer (ii).

[0075] <Other Layers> The laminate obtained by the production method of the present invention may have layers other than the substrate (i) and the urethane foam layer (ii). Examples of the other layers include a surface layer (iii).

[0076] <Skin Layer> The skin layer (iii) can be formed using a known material by a known method.

[0077] The surface layer (iii) contains, for example, a solvent-based urethane resin, a water-based urethane resin, a silicone resin, a polypropylene resin, a polyester resin, or the like.

[0078] Among the above, the surface layer (iii) preferably contains a urethane resin (A) having a nonionic group, and more preferably contains the same urethane resin as the urethane resin contained in the above-mentioned urethane foam layer (ii).

[0079] If necessary, a surface treatment layer (iv) may be further provided on the surface layer (iii) for the purpose of improving scratch resistance, imparting gloss, etc. Examples of materials for forming the surface treatment layer (iv) include known aqueous urethane resins, solvent-based urethane resins, solventless urethane resins, aqueous acrylic resins, silicone resins, polypropylene resins, polyester resins, vinyl chloride resins, etc. These materials can be used alone or in combination of two or more.

[0080] (Method for Producing Laminate) The method for producing the laminate of the present invention is not particularly limited as long as it includes step (X) of applying a urethane foam layer-forming material onto a release paper to form a urethane foam layer (ii), step (Y) of bonding the substrate (i) onto the urethane foam layer (ii) by a wet lamination method, and step (Z) of peeling off the release paper. However, it is preferable to perform the steps (X), (Y), and (Z) in this order.

[0081] The method for forming the urethane foam layer (ii) in the step (X) is not particularly limited, and examples thereof include a method in which a urethane foam layer-forming material is foamed to obtain a foamed liquid, and the foamed liquid is applied to a release paper and dried.

[0082] Methods for foaming the urethane foam layer-forming material to obtain a foamed liquid include, for example, manual stirring and mechanical foaming using a mixer such as a mechanical mixer. Among these, the method using a mixer is preferred because it allows for easy preparation of a foamed liquid. When a mixer is used, for example, a method of stirring at 500 to 3,000 rpm for 10 seconds to 10 minutes can be mentioned. In this case, in order to obtain a urethane foam layer (ii) with a good texture, it is preferable to increase the volume of the material before and after foaming by 1.2 to 7 times, and more preferably by 1.3 to 2 times.

[0083] In the step (Y), the urethane foam layer (ii) and the substrate (i) are bonded together by a wet lamination method, which in the present invention refers to a method in which a urethane foam layer-forming material is applied to a release-treated substrate and then bonded to the substrate before the material is completely cured.

[0084] (Synthetic Leather) The laminate obtained by the above-described production method of the present invention has quick peelability, a soft texture, and good processability, and is therefore particularly suitable for use as synthetic leather.

[0085] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[0086] [Synthesis of Urethane Resin] <Synthesis of Urethane Resin (AX-1)> In the presence of 0.1 parts by mass of stannous octoate, 1,000 parts by mass of polyether polyol (Mitsubishi Chemical Corporation "PTMG2000", number average molecular weight: 2,000), 38 parts by mass of polyethylene glycol (NOF Corporation "PEG600", number average molecular weight: 600), and 262 parts by mass of dicyclohexylmethane diisocyanate were reacted at 100 ° C. until the NCO% reached 2.8% by mass to obtain a urethane prepolymer A1. 1,000 parts by mass of urethane prepolymer A1 heated to 70 ° C. was mixed with 200 parts by mass of a 20% by mass aqueous solution of sodium dodecylbenzenesulfonate (Dai-ichi Kogyo Seiyaku Co., Ltd. "Neogen S-20F") and 467 parts by mass of water to obtain an emulsion. Thereafter, an aqueous dilution of piperazine with an amino group content equivalent to 95% of the NCO groups was immediately added to cause chain extension, and finally an aqueous dispersion of urethane resin (AX-1) with a non-volatile content of 55% by mass of the urethane resin was obtained. Next, the aqueous dispersion of urethane resin (AX-1) was applied to release paper (coating thickness 150 μm) and dried in a hot air dryer at 70 ° C. for 4 minutes, then at 120 ° C. for 2 minutes to obtain a dried product. This dried product was measured using a flow tester "CFT-500A" manufactured by Shimadzu Corporation (using a die with a diameter of 1 mm and a length of 1 mm, a load of 98 N, and a temperature rise rate of 3 ° C. / min). The flow initiation temperature of the urethane resin (AX-1) was 180 ° C.

[0087] <Synthesis of Urethane Resin (AX-2)> In the presence of 0.1 parts by mass of stannous octoate, 1,000 parts by mass of polycarbonate polyol (Ube Industries, Ltd. "ETERNACOLL UH-100", number average molecular weight: 1,000), 75 parts by mass of polyethylene glycol (NOF Corporation "PEG600", number average molecular weight: 600), and 525 parts by mass of dicyclohexylmethane diisocyanate were reacted at 100 ° C. until the NCO% reached 4.6% by mass to obtain urethane prepolymer A2. 1,000 parts by mass of urethane prepolymer A2 heated to 70 ° C. was mixed with 200 parts by mass of a 20% by mass aqueous solution of sodium dodecylbenzenesulfonate (Dai-ichi Kogyo Seiyaku Co., Ltd. "Neogen S-20F") and 325 parts by mass of water to obtain an emulsion. Immediately thereafter, an aqueous solution of piperazine having an amino group content equivalent to 95% of the NCO groups was added to cause chain elongation, thereby finally obtaining an aqueous dispersion of urethane resin (AX-2) having a non-volatile content of 55% by mass. The flow initiation temperature of urethane resin (AX-2), measured in the same manner as above, was 175°C.

[0088] <Synthesis of Urethane Resin (AX-3)> An aqueous dispersion of urethane resin (AX-3) was obtained in the same manner as in <Synthesis of Urethane Resin (AX-2)> above, except that the polyether polyol was changed to a polyester polyol ("Placcel 210" manufactured by Daicel Corporation, number average molecular weight: 1,000). The flow initiation temperature of urethane resin (AX-3), measured in the same manner as above, was 160°C.

[0089] <Synthesis of Urethane Resin (X-4)> In the presence of 0.1 parts by mass of stannous octoate, 1,000 parts by mass of polyether polyol ("PTMG2000" manufactured by Mitsubishi Chemical Corporation, number average molecular weight: 2,000), 38 parts by mass of polyethylene glycol ("PEG600" manufactured by NOF Corporation, number average molecular weight: 600), and 262 parts by mass of dicyclohexylmethane diisocyanate were reacted at 100 ° C. until the NCO% reached 2.8% by mass to obtain a urethane prepolymer A1. 1,000 parts by mass of urethane prepolymer A1 heated to 70 ° C. was mixed with 200 parts by mass of a 20% by mass aqueous solution of sodium dodecylbenzenesulfonate ("Neogen S-20F" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and 467 parts by mass of water to obtain an emulsion. Immediately thereafter, an aqueous solution of piperazine having an amino group content corresponding to 75% of the NCO groups was added to cause chain elongation, thereby finally obtaining an aqueous dispersion of urethane resin (X-4) having a non-volatile content of 55% by mass. The flow initiation temperature of urethane resin (X-4), measured in the same manner as above, was 130°C.

[0090] <Preparation of Urethane Resin (X-5)> An ether-based PUD "Hydran WLS-120AR" (manufactured by DIC Corporation) was prepared as the urethane resin (X-5). The flow initiation temperature of the urethane resin (X-5), measured in the same manner as above, was 160°C.

[0091] <Synthesis of Urethane Resin (X-6) for Adhesive Layer> In the presence of 1,225 parts by mass of methyl ethyl ketone and 0.1 parts by mass of stannous octoate, 1,000 parts by mass of polyether polyol ("PTMG1000" manufactured by Mitsubishi Chemical Corporation, number average molecular weight: 1,000), 50 parts by mass of 2,2'-dimethylolpropionic acid, and 175 parts by mass of isophorone diisocyanate were reacted at 70 ° C. until the solution viscosity reached 20,000 mPa s, and then 3 parts by mass of methanol was added to terminate the reaction, yielding a methyl ethyl ketone solution of an anionic urethane resin. 61 parts by mass of polyoxyethylene distyrenated phenyl ether and 38 parts by mass of triethylamine were mixed with this urethane resin solution, and then 2,450 parts by mass of ion-exchanged water was added to cause phase inversion emulsification, yielding an emulsion in which the urethane resin was dispersed in water. Next, methyl ethyl ketone was distilled off from the emulsion to obtain an aqueous dispersion of urethane resin (X-6) with a nonvolatile content of 50% by mass.

[0092] [Method for Producing Laminate] <Laminate (1) of Example 1> Preparation of Foam Layer Composition (X1) 100 g of the aqueous dispersion of urethane resin (AX-1), 2.0 g of a thickener (Borch Gel ALA; manufactured by Borchers), and 3.0 g of a surfactant (ammonium stearate) were stirred at 2,400 rpm in a mechanical mixer, and air was incorporated to prepare a foam layer composition (X1) with a volume of 150% of the initial volume.

[0093] Preparation of Laminate (1) of Example 1 The foam layer composition (X1) was applied to release paper (EK-100D; manufactured by Lintech) using a knife coater (coating thickness: 600 μm) to form a foam layer. Next, a substrate (thermoplastic urethane (TPU)) was pressure-bonded to the foam layer, thereby bonding the foam layer and the substrate together. Thereafter, the laminate (1) (synthetic leather) of Example 1 was obtained by drying at 120°C for 4 minutes. The dry density of the urethane foam layer in this laminate (1) was 630 kg / m ３ In the present invention, the dry density of the urethane foam layer is the value obtained by subtracting the weight of the substrate per 10 cm square from the weight of the laminate of Example 1 per 10 cm square, and dividing the result by the thickness of the urethane foam layer (the same applies hereinafter).

[0094] Laminate (2) of Example 2 A laminate (2) of Example 2 was produced by the same production method as in the laminate of Example 1, except that the aqueous dispersion of urethane resin (AX-1) in the foam layer composition (X1) was changed to an aqueous dispersion of urethane resin (AX-2). The dry density of the urethane foam layer in this laminate (2) was 520 kg / m ３ It was.

[0095] Laminate (3) of Example 3 A laminate (3) of Example 3 was produced in the same manner as in the laminate of Example 1, except that the aqueous dispersion of urethane resin (AX-1) in the foam layer composition (X1) was changed to an aqueous dispersion of urethane resin (AX-3). The dry density of the urethane foam layer in this laminate (3) was 780 kg / m ３ It was.

[0096] <Laminate (R1) of Comparative Example 1> A laminate (R1) of Comparative Example 1 was produced by the same production method as in <Laminate of Example 1>, except that the aqueous dispersion of urethane resin (AX-1) in the foam layer composition (X1) was changed to an aqueous dispersion of urethane resin (X-4). The dry density of the urethane foam layer in this laminate (R1) was 600 kg / m ３ It was.

[0097] <Laminate (R2) of Comparative Example 2> A laminate (R2) of Comparative Example 2 was produced by the same production method as in <Laminate of Example 1>, except that the aqueous dispersion of urethane resin (AX-1) in the foam layer composition (X1) was changed to an aqueous dispersion of urethane resin (X-5) and 4.0 g of a crosslinking agent (Carbodilite SV-02; manufactured by Nisshinbo Chemical Inc.) was further blended.

[0098] <Laminate (R3) of Comparative Example 3> A laminate (R3) of Comparative Example 3 was produced by the same production method as in <Laminate of Example 1>, except that the aqueous dispersion of urethane resin (AX-1) in the composition for foam layer (X1) was changed to an aqueous dispersion of urethane resin (X-5).

[0099] <Laminate (R4) of Comparative Example 4> Preparation of adhesive layer composition 100 g of the aqueous dispersion of urethane resin (X-6), 0.1 g of an antifoaming agent (Tego Foamex 800; manufactured by Evonik), and 1.0 g of a thickener (Borch Gel 0620; manufactured by Borchers) were stirred at 2000 rpm for 2 minutes using a mechanical mixer, and then defoamed using a vacuum defoamer to prepare an adhesive layer composition (X-6).

[0100] Preparation of Laminate (R4) of Comparative Example 4 The foam layer composition (X1) was coated on release paper (EK-100D; manufactured by Lintech) using a knife coater (coating thickness 600 μm) to form a foam layer (drying conditions: 70 ° C × 2 min, 120 ° C × 2 min). Next, the adhesive layer composition (X-6) was coated on the foam layer using a knife coater (adjusting the coating thickness so that the coating thickness when dried would be 50 μm), and an adhesive layer was formed using a hot air dryer (drying conditions: 90 ° C, 3 minutes). A substrate (thermoplastic urethane (TPU)) was placed on the adhesive layer and bonded using a laminator at a temperature of 100 ° C, a pressure of 7.5 MPa, and a feed rate of 0.5 m / min to obtain the laminate (R4) of Comparative Example 4.

[0101] <Laminate (R5) of Comparative Example 5> The foam layer composition (X1) was coated on release paper (EK-100D; manufactured by Lintech) using a knife coater (coating thickness 600 μm) to form a foam layer (drying conditions: 70 ° C. × 2 min, 120 ° C. × 2 min). Next, the adhesive layer composition (X-6) was coated on the foam layer using a knife coater (coating thickness adjusted so that the coating thickness when dried would be 50 μm), and a substrate (thermoplastic urethane (TPU)) was placed on the adhesive layer and bonded with a laminator at a temperature of 25 ° C., a pressure of 5 MPa, and a feed rate of 0.5 m / min. The adhesive layer was then dried in a hot air dryer (drying conditions: 120 ° C. × 2 min) to obtain the laminate (R5) of Comparative Example 5.

[0102] The laminates obtained in the above Examples and Comparative Examples were subjected to the following evaluations.

[0103] [Evaluation of Peel Strength] A 2.5 cm wide hot melt tape (BW-2, manufactured by Sun Chemical Industry Co., Ltd.) was placed on the surface of the laminate and heated and pressed at 150°C for 30 seconds to adhere the hot melt tape. The laminate was cut along the width of the hot melt tape. The substrate and the hot melt tape were clamped with a zipper, and the substrate and foam layer of the cut laminate were peeled off, and the peel strength was measured using an autograph (manufactured by Shimadzu Corporation). The average value of the obtained data was calculated and converted to a 1 cm width, and the peel strength was evaluated according to the following criteria. The results are shown in Tables 1 and 2.

[0104] A: 3 kgf / cm or more B: 1.5 to less than 3 kgf / cm C: Less than 1.5 kgf / cm

[0105] The peel strength of each laminate was measured immediately after production and after aging (heating at 60°C for a week), and the peelability was evaluated according to the following criteria. The results are shown in Tables 1 and 2.

[0106] A: The difference in peel strength is less than 0.5 kgf / cm. B: The difference in peel strength is 0.5 kgf / cm or more.

[0107] [Evaluation of Hydrolysis Resistance] The laminate of each example was left standing under humid heat conditions of 70° C. and 95% RH for 3 weeks, and the hydrolysis resistance was evaluated according to the following criteria. The results are shown in Tables 1 and 2.

[0108] A: No abnormality in appearance. B: Change in gloss of appearance and / or sticky feel.

[0109] [Evaluation of Processability] The laminates of each example were embossed. The appearances of the laminates of each example were then compared, and the laminates were observed using a scanning electron microscope (SEM) to determine whether the pattern was transferred more clearly. The processability was evaluated according to the following criteria. The results are shown in Tables 1 and 2.

[0110] A: The embossed pattern is clearly reproduced, and SEM observation confirms that the pattern is sharp. B: The embossed pattern is not clearly reproduced, and SEM observation confirms that the pattern is not sharp.

[0111] [Evaluation of Texture] The texture of each laminate was evaluated by touch.

[0112] A: Flexible and soft. B: Less flexible and hard.

[0113]

[0114]

[0115] As shown in Tables 1 and 2, the laminates of the Examples were superior to the laminates of the Comparative Examples in the evaluation results of peel strength, quick releasability, hydrolysis resistance, processability, and texture. Therefore, it was confirmed that the laminates of the Examples had quick releasability, a soft texture, and good processability.

Claims

1. A method for manufacturing a laminate comprising a base material (i) and a urethane foam layer (ii), A step of applying a urethane foam layer forming material onto a release paper to form a urethane foam layer (ii), A step of bonding the substrate (i) onto the urethane foam layer (ii) by a wet lamination method, The process includes the step of peeling off the aforementioned release paper, The urethane foam layer (ii) is in direct contact with the substrate (i), The urethane foam layer forming material contains a urethane resin (A) having nonionic groups, The flow initiation temperature of the urethane resin (A) is above 130°C. The urethane resin (A) is made from polyisocyanate (a1), one or more polyols (a2) selected from the group consisting of polyether polyols, polycarbonate polyols, and polyester polyols, and a compound (a4) having an oxyethylene structure as essential raw materials. A method for producing a laminate, characterized in that the proportion of the compound having the oxyethylene structure (a4) used is in the range of 0.1 to 10% by mass of the total mass of the raw materials constituting the urethane resin (A).

2. The method for manufacturing a laminate according to claim 1, wherein the flow initiation temperature of the urethane resin (A) is 150°C or higher.

3. The method for producing a laminate according to claim 1, wherein the urethane foam layer (ii) further contains a surfactant.

4. The method for producing a laminate according to claim 3, wherein the surfactant is a long-chain carboxylate.

5. The dry density of the aforementioned urethane foam layer (ii) is 200 to 1000 kg / m³ ３ The method for manufacturing a laminate according to claim 1.

6. A method for producing synthetic leather, characterized by having a laminate obtained by the manufacturing method described in any one of claims 1 to 5.