Synthetic leather manufacturing method and synthetic leather manufacturing device

Abstract

The problem to be solved by the present invention is to provide a method for producing synthetic leather without using release paper. The present invention solves the above-mentioned problems by a method for producing synthetic leather including a skin layer, the method including a step of forming the skin layer by an inkjet method, and a synthetic leather production device that includes a substrate transport means or an inkjet head moving means, an inkjet head, and a dryer and forms the skin layer by the inkjet method. The method and device make it possible to obtain synthetic leather without using release paper, thereby reducing waste.

Description

[Background technology]

[0001] Due to its mechanical strength and good texture, urethane resins are widely used in synthetic leather (including artificial leather), coating agents, adhesives, gloves, clothing, etc. The mainstream of the urethane resin compositions has been solvent-based urethane resin compositions containing N,N-dimethylformamide (DMF). Meanwhile, against the backdrop of DMF regulations in Europe, strengthened VOC emission regulations in China and Taiwan, and DMF regulations by major apparel manufacturers, urethane resin aqueous dispersions (polyurethane dispersions) in which urethane resin compositions are dispersed in water are beginning to be used for the above applications.

[0002] Synthetic leather reproduces the texture of natural leather by applying a synthetic resin onto a substrate. Synthetic leather has at least a substrate and a layer called a surface layer, and may further have a microporous layer called an intermediate layer between the substrate and the surface layer to obtain a high-quality texture and feel. In addition, an adhesive layer may be formed between each layer to improve the adhesion of each layer. Furthermore, a surface treatment layer or a decorative layer may be formed on the surface layer to provide a touch or gloss or to add a color pattern.

[0003] A typical method for producing synthetic leather using an aqueous urethane resin dispersion is to use release paper to maintain the smoothness of the surface, to protect the synthetic leather surface from dirt and dust, or to impart a design (such as an uneven or grained pattern) to imitate natural leather (see, for example, Patent Document 1). In this method, a urethane resin composition paint for a surface layer is applied to a release paper and dried and solidified, and then a urethane resin composition paint for an intermediate layer that has been subjected to the foaming treatment is applied thereon and dried and solidified. The intermediate layer coated surface is then thermocompressed to a substrate such as a base fabric, and the release paper is peeled off after cooling.

[0004] In the above synthetic leather manufacturing method, the release paper is disposable, which poses potential problems in terms of cost and environmental impact. In addition, both the surface layer and the middle layer need to be painted, and there are problems with the large amount of paint that is not used after manufacturing, and waste liquid from cleaning the manufacturing equipment and machinery used.

[0005] On the other hand, in recent years, there has been a demand for colorful designs and changes in design, and efforts have been made to apply decorative layers to the synthetic leather surface directly using inkjet printing or transfer printing using transfer films in order to further improve design (see, for example, Patent Documents 2 and 3). However, although this layer formation method can add decoration, it does not contribute to reducing the use of release paper.

[0006] For example, in the manufacture of vehicle seats, a synthetic leather sheet that is separately manufactured is cut and sewn, and then covered with a cushioning material for the vehicle seat. However, the sewing work is done manually and is time-consuming, and the finished product varies greatly, and a lot of scraps from the cutting are discarded. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2011-94268 A [Patent Document 2] JP 2008-57062 A [Patent Document 3] JP 2007-111867 A Summary of the Invention [Problem to be solved by the invention]

[0008] In view of the above, an object of the present invention is to provide a method for producing synthetic leather without using release paper.

[0009] Another problem to be solved by the present invention is to provide a method for producing synthetic leather for vehicle seats which eliminates the sewing process. [Means for solving the problem]

[0010] The present invention solves the above-mentioned problems by providing a method for producing synthetic leather including a skin layer, the method including a step of forming the skin layer by an inkjet system, and a synthetic leather production apparatus that includes a substrate transport means or an inkjet head moving means, an inkjet head, and a dryer, and that forms the skin layer by the inkjet system.

[0011] The inkjet method is known as a method for forming an image by discharging minute droplets onto a substrate. Also, inkjet discharging is only possible with low-viscosity ink. Therefore, it is not possible to discharge synthetic leather paint, which has a very high viscosity compared to inkjet ink, and it has generally been thought that the inkjet method cannot be used to manufacture synthetic leather.

[0012] However, the present inventors have found, after extensive research into the properties of paints for synthetic leather, that a urethane resin aqueous dispersion can be adjusted relatively easily to a viscosity suitable for inkjet ejection. With conventional solvent-based urethane resin compositions, the urethane resin composition is dissolved in a solvent, so even if the solvent is increased to dilute the composition, it is difficult to reduce the viscosity due to entanglement of the resin. On the other hand, with the urethane resin aqueous dispersion, particles of the urethane resin composition are dispersed in water, and the interaction between the resin particles is relatively small, so that dilution with an aqueous medium makes it possible to sufficiently reduce the viscosity.

[0013] That is, the present inventors have found that, by studying the properties of paints for synthetic leather, paints for synthetic leather, which are originally highly viscous, can be adjusted to a viscosity suitable for inkjet ejection. As a result, the present inventors have found that if a urethane resin water dispersion is ejected by inkjet onto a substrate such as a base fabric, synthetic leather can be produced without using a release paper, and furthermore, compared to the application of paint, waste paint and washing waste liquid can be reduced. The present inventors have also found that if a urethane resin water dispersion containing a pigment is ejected by inkjet onto a substrate such as a base fabric, decoration can be performed simultaneously with layer formation, and defects associated with the additional formation of a decorative layer do not occur.

[0014] Furthermore, the present inventors conducted further studies and found that even if the ink for synthetic leather has been adjusted to a viscosity suitable for inkjet ejection, it is possible to obtain synthetic leather by applying the ink to a substrate such as a base fabric using an inkjet system and drying the ink.

[0015] Furthermore, the present inventors have found that by polymerizing an active energy ray-curable paint containing urethane acrylate, a synthetic leather similar to that obtained by applying a paint for synthetic leather can be obtained, and that the viscosity of such an active energy ray-curable paint containing urethane acrylate can also be adjusted to a level suitable for inkjet ejection.

[0016] That is, the present inventors have found that if an active energy ray curable paint containing urethane acrylate is ink-jet-discharged onto a substrate such as a base fabric and then polymerized and dried, synthetic leather can be produced without using release paper, and furthermore, waste paint and washing waste liquid can be reduced compared to coating of paint, and VOCs can be reduced compared to solvent-based paints.The present inventors have also found that if an active energy ray curable paint containing a pigment and urethane acrylate is ink-jet-discharged onto a substrate such as a base fabric and then polymerized and dried, decoration can be performed simultaneously with layer formation, and defects associated with additional formation of a decorative layer do not occur.

[0017] Furthermore, the inventors realized that by forming synthetic leather directly onto the cushioning material for vehicle seats, it is possible to eliminate the conventional process of cutting and sewing a separately manufactured synthetic leather sheet and then covering the cushioning material for vehicle seats, thereby making it possible to significantly reduce the number of processes and waste, thereby reducing the environmental burden. An example of the configuration of the present invention that solves the above problem is as follows.

[0018] Item 1. A method for producing synthetic leather including a skin layer, comprising forming the skin layer by an inkjet method.

[0019] Item 2. A method for producing a synthetic leather according to Item 1, comprising the step of applying an aqueous urethane resin dispersion containing at least a urethane resin composition and water by an inkjet method and then drying the applied dispersion to form the surface layer.

[0020] Item 3. The method for producing a synthetic leather according to Item 2, wherein the urethane resin composition has an anionic group and / or a nonionic group.

[0021] Item 4. The method for producing a synthetic leather according to Item 2 or 3, wherein the urethane resin water dispersion further contains a pigment.

[0022] Item 5. The method for producing synthetic leather according to Item 4, wherein the pigment is carbon black or titanium oxide.

[0023] Item 6. The method for producing a synthetic leather according to any one of Items 1 to 5, wherein the synthetic leather further comprises a fibrous base material, and the fibrous base material has a form selected from the group consisting of a nonwoven fabric, a knitted fabric, and a woven fabric.

[0024] Item 7. The method for producing a synthetic leather according to any one of Items 1 to 6, further comprising a step of forming a surface treatment layer on the surface of the skin layer using a surface treatment agent.

[0025] Item 8. The method for producing a synthetic leather according to any one of Items 1 to 7, wherein the synthetic leather further includes an intermediate layer, and the method includes a step of forming the intermediate layer by an inkjet method.

[0026] Item 9. A synthetic leather manufacturing apparatus comprising a substrate transport means or an inkjet head moving means, an inkjet head, and a dryer, and forming a skin layer by an inkjet method. Effect of the Invention

[0027] The manufacturing method and manufacturing apparatus of the present invention make it possible to obtain synthetic leather without using release paper, thereby reducing waste. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic diagram showing one embodiment of the method for producing the synthetic leather of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing one embodiment of the method for producing the synthetic leather of the present invention. [Diagram 3] FIG. 3 is a schematic diagram showing one embodiment of the synthetic leather obtained by the method for producing a synthetic leather of the present invention. [Figure 4] FIG. 4 is a schematic diagram showing another embodiment of the synthetic leather obtained by the method for producing a synthetic leather of the present invention. [Diagram 5] FIG. 5 is a schematic diagram showing one embodiment of the method for producing the synthetic leather of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] (Manufacturing method of synthetic leather) The method for producing synthetic leather according to the present embodiment is a method for producing synthetic leather including a skin layer, and includes a step of forming the skin layer by an inkjet method.

[0030] Hereinafter, preferred embodiments of the manufacturing method of the present invention will be described with reference to the drawings, but the present invention is not limited to the following contents, and each configuration can be appropriately changed without departing from the spirit of the invention. In addition, the drawings are schematic diagrams that are not strict reproductions, and sizes, etc. are not strictly expressed.

[0031] FIG. 3 is a schematic diagram showing one embodiment of synthetic leather obtained by the method for producing synthetic leather of the present invention. Synthetic leather 150 obtained by the method for producing synthetic leather of the present invention includes a skin layer 130. In addition, the synthetic leather 150 is preferably one in which the skin layer 130 is laminated on the fibrous substrate 100, and is also preferably one in which the intermediate layer 120 is included between the fibrous substrate 100 and the skin layer 130. In addition, the synthetic leather 150 is also preferably one in which the primer layer 110 is included between the fibrous substrate 100 and the skin layer 130 or between the fibrous substrate 100 and the intermediate layer 120. Furthermore, although not shown in FIG. 3, the synthetic leather 150 is also preferably one in which a surface treatment layer is included on the skin layer 130.

[0032] FIG. 1 is a schematic diagram of one embodiment of the manufacturing method of the present invention. First, a fibrous substrate 100 is conveyed from a substrate roll 70. At this time, for example, a laminate in which a primer layer 110 and an intermediate layer 120 are laminated on the fibrous substrate 100 may be conveyed as the substrate. In the skin layer forming process, a skin layer forming liquid 32 is discharged from a skin layer inkjet head 31 installed at the destination of the fibrous substrate 100, and dried by a skin layer dryer 33 as necessary. If necessary, it is confirmed that the film thickness is an arbitrary thickness by a skin layer thickness meter 34, and the synthetic leather 150 is wound on a product winding roll 80 via a guide roll 50 as necessary. When each process is performed inline as in the present invention, compared with the conventional synthetic leather manufacturing method, it leads to a reduction in the number of processes, and it is possible to reduce the overall CO2 emissions in the synthetic leather manufacturing process. Furthermore, the synthetic leather manufacturing process can be fully automated, and small-scale production and timely and appropriate production are also easy.

[0033] (epidermal layer) The skin layer 130 is formed on the fibrous base material 100 or the intermediate layer 120, and has the function of reproducing the texture of natural leather. In the present invention, the skin layer 130 is formed by an inkjet method. The surface layer 130 in the present invention is preferably composed of a material containing a component having a urethane skeleton in order to give it the texture of synthetic leather.

[0034] (Step of forming the epidermis layer by the inkjet method) The step of forming the surface layer 130 by the inkjet method in the present invention is the surface layer forming step in Fig. 1, which is a step in which the method of applying the surface layer forming liquid 32, which is a paint that becomes the surface layer when dried, is the inkjet method. The surface layer 130 may be formed on the fibrous substrate 100, on the intermediate layer 120, or on another layer (for example, an adhesive layer, a primer layer 110, etc.). Note that a laminate in which the intermediate layer 120, the primer layer 110, etc. are laminated on the fibrous substrate 100 may be collectively referred to as a substrate. The step of forming the surface layer by the inkjet method may be carried out only once, or may be carried out two or more times to obtain the required film thickness. The skin layer forming liquid 32, which becomes the skin layer 130 when dried, is preferably a paint containing a component having a urethane skeleton in order to produce the texture of synthetic leather, more preferably an aqueous urethane resin dispersion or an active energy ray curable paint containing urethane acrylate, and even more preferably an aqueous urethane resin dispersion.

[0035] (Inkjet method) The inkjet method is a method in which a liquid, also known as ink, is passed through an inkjet head and ejected from the inkjet head onto a substrate in the form of fine droplets, thereby making it possible to apply the liquid onto a substrate. The inkjet method in the present invention is not particularly limited, but examples thereof include a continuous jet type (charge control type, spray type, etc.), an on-demand type (piezo type, thermal type, electrostatic suction type, etc.), and the like.

[0036] The step of forming the epidermis layer by the inkjet method is the epidermis layer forming step in Fig. 1, and specifically, for example, is a step of supplying an epidermis layer forming liquid 32 to an inkjet head 31 positioned above the transported fibrous substrate 100, adjusting the temperature as necessary, and then discharging and applying the epidermis layer forming liquid 32 onto the fibrous substrate 100 by the inkjet method. The epidermis layer 130 may be formed on the fibrous substrate 100, on the intermediate layer 120, or on other layers (for example, an adhesive layer or a primer layer 110). In addition, it is also preferable to have an epidermis layer drying step in which the applied epidermis layer forming liquid 32 is dried in a dryer 33 after the step. By forming the surface layer using the inkjet method, synthetic leather can be manufactured without using disposable release paper, which reduces waste and also reduces waste liquid in all processes, including the washing process, compared to conventional manufacturing methods. Also, by using multiple colors of surface layer forming liquids, decoration can be performed at the same time.

[0037] The fibrous substrate to be transported may already have an intermediate layer formed by a conventional wet method. That is, the skin layer forming step may be performed on the fibrous substrate 100, or the layered product in which the intermediate layer is formed on the fibrous substrate may be transported as the fibrous substrate 100 and the skin layer forming step may be performed on the layered product.

[0038] The fibrous base material may be transported by a so-called roll-to-roll method in which the rolled fibrous base material is wound using a product winding roll 80 or a guide roll 50, or by a so-called sheet-feed method in which the fibrous base material cut to a certain size is transported one by one, but from the viewpoint of manufacturing efficiency, it is preferable to use a roll-to-roll method in which all steps can be in-lined. In addition, the roll-to-roll method may be a method in which the fibrous base material is transported continuously, or may be a step-feed method in which the fibrous base material is transported intermittently.

[0039] The inkjet head may be arranged in a line head configuration in which a plurality of inkjet heads are arranged across the width of the fibrous substrate, or may be used in a serial head configuration in which one or a plurality of inkjet heads are mounted on a carriage that is driven left and right to eject ink, but from the viewpoint of manufacturing efficiency, a line head configuration capable of high-speed coating is preferable. In addition, in order to eject ink efficiently in large amounts, a plurality of inkjet head groups arranged in a line head configuration may be used.

[0040] In order to efficiently ensure the film thickness, the discharge amount of the skin layer forming liquid is preferably 15 to 5000 pL, and more preferably 15 to 2500 pL. The discharge amount can be adjusted by selecting the type of inkjet head used, but it can also be finely adjusted by the driving waveform when driving the inkjet head, and the physical properties of the ink such as the viscosity and surface tension.

[0041] The epidermal layer forming liquid 32 is preferably subjected to a degassing process before being supplied to the inkjet head. Specifically, the dissolved oxygen concentration in the epidermal layer forming liquid is preferably 8.0 ppm or less, more preferably 5.0 ppm or less, before being supplied to the inkjet head. The degassing process is preferably performed through a degassing module installed before the path leading to the inkjet head. The degassing process improves the stability of the inkjet discharge, allowing stable application for a long period of time.

[0042] Furthermore, before being supplied to the inkjet head, the epidermis layer forming liquid 32 is preferably subjected to a filtering process in which the liquid is passed through a filter that removes coarse particles and the like. Specifically, the liquid is preferably passed through a filter of 50 μm or less. The filtering process is preferably carried out through a capsule filter or the like that is installed before the path leading to the inkjet head. This filtering process makes it difficult for the nozzle of the inkjet head to become clogged, and allows stable application for a long period of time.

[0043] The skin layer forming liquid 32 may be supplied to the inkjet head by a pump, by using a head difference, or by adjusting negative pressure.

[0044] The temperature of the epidermal layer forming liquid 32 may be adjusted by heating the inkjet head, by heating the supply path for supplying the epidermal layer forming liquid 32, or by heating the tank of the epidermal layer forming liquid 32, but it is preferable to heat the inkjet head for stable temperature adjustment. The inkjet head may be heated by a temperature regulator installed outside the inkjet head or by a temperature regulator built into the inkjet head. The temperature is adjusted to a viscosity that allows stable discharge of the epidermis layer forming liquid 32. In order to reduce the effect of temperature rise due to long-term operation, the adjusted temperature is preferably 20 to 60°C, and more preferably 25 to 50°C.

[0045] In order to apply the epidermis layer forming liquid 32 evenly onto the substrate, it is preferable that the inkjet head is located close to the substrate, and more specifically, the distance between the substrate and the ejection surface of the inkjet head is preferably 10 mm or less. In order to prevent the substrate from coming into contact with the ejection surface of the inkjet head and deteriorating the inkjet head, the distance between the substrate and the ejection surface of the inkjet head is preferably 0.6 mm or more, and more preferably 1.0 mm or more. More specifically, it is preferably 0.6 to 10 mm, more preferably 1.0 to 10 mm, and even more preferably 1.0 to 5.0 mm.

[0046] The viscosity of the skin layer forming liquid 32 is not particularly limited, but it is preferably a viscosity that allows it to be ejected by inkjet, and the ejection viscosity (for example, when adjusted to 25°C using a temperature regulator, the viscosity at 25°C) is preferably 5 to 500 mPa·s, more preferably 8 to 200 mPa·s, and even more preferably 8 to 100 mPa·s.

[0047] The surface tension of the skin layer forming liquid 32 is not particularly limited, but is preferably a surface tension that allows inkjet ejection, and is preferably 15 to 50 mN / m at 25° C., and more preferably 20 to 40 mN / m.

[0048] The thickness of the surface layer after drying is not particularly limited as long as it is an appropriate thickness for synthetic leather, but is preferably 0.5 to 100 μm, more preferably 5 to 70 μm, and even more preferably 20 to 50 μm.

[0049] The above-mentioned surface layer drying step is not particularly limited and can be carried out using a known dryer, for example, drying with a heat roll, drying with an oven, drying with an air dryer, drying by irradiation with near-infrared rays, etc. In addition, when the coating material containing a component having a urethane skeleton is an active energy ray curable coating material, the drying step may be curing drying by irradiation with ultraviolet rays or curing drying by irradiation with electron beams.

[0050] At the end of the process of forming the skin layer by the inkjet method, it is preferable to install a thickness meter 34 in order to control the thickness of the skin layer. The thickness meter is not particularly limited, and any known thickness meter can be used, such as an electromagnetic thickness meter, an eddy current thickness meter, an ultrasonic thickness meter, a reflection spectroscopic thickness meter, or a fluorescent X-ray thickness meter. It is preferable to use a reflection spectroscopic thickness meter or a fluorescent X-ray thickness meter, which are non-contact thickness meters advantageous for in-line measurement. However, if in-line measurement is not performed, the film thickness can be determined from a cross-sectional photograph of the synthetic leather 150 taken with an electron microscope. Any method that can determine the film thickness can be applied, and there are no particular limitations.

[0051] (Urethane resin water dispersion) The surface layer forming liquid 32 is preferably a urethane resin water dispersion. The urethane resin water dispersion contains at least a urethane resin composition and water. A urethane resin composition is a general term for polymeric compounds having a urethane bond (-NHCOO-), and is generally produced by reacting (crosslinking / curing reaction) polyol with polyisocyanate.

[0052] The urethane resin composition is dispersible in water, and examples of the urethane resin composition include a urethane resin composition having a hydrophilic group such as an anionic group, a cationic group, or a nonionic group; a urethane resin composition forcibly dispersed in water with an emulsifier, and the like. These urethane resin compositions may be used alone or in combination of two or more. Among them, it is preferable that the urethane resin composition has an anionic group and / or a nonionic group.

[0053] The method for obtaining the urethane resin composition having an anionic group may, for example, be a method using, as a raw material, one or more compounds selected from the group consisting of compounds having a carboxyl group and compounds having a sulfonyl group.

[0054] Examples of the compound having a carboxyl group that can be used include 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolpropionic acid, 2,2-valeric acid, etc. These compounds may be used alone or in combination of two or more.

[0055] Examples of the compound having a sulfonyl group that can be used include 3,4-diaminobutanesulfonic acid, 3,6-diamino-2-toluenesulfonic acid, 2,6-diaminobenzenesulfonic acid, N-(2-aminoethyl)-2-aminoethylsulfonic acid, etc. These compounds may be used alone or in combination of two or more.

[0056] The carboxyl group and sulfonyl group may be partially or completely neutralized with a basic compound in the resin composition. Examples of the basic compound include organic amines such as ammonia, triethylamine, pyridine, and morpholine; alkanolamines such as monoethanolamine and dimethylethanolamine; and metal base compounds including sodium, potassium, lithium, and calcium.

[0057] The urethane resin composition having a cationic group can be obtained, for example, by using one or more compounds having an amino group as raw materials.

[0058] Examples of the compound having an amino group include compounds having primary and secondary amino groups such as triethylenetetramine and diethylenetriamine, compounds having a tertiary amino group such as N-alkyldialkanolamines such as N-methyldiethanolamine and N-ethyldiethanolamine, and N-alkyldiaminoalkylamines such as N-methyldiaminoethylamine and N-ethyldiaminoethylamine, etc. These compounds may be used alone or in combination of two or more.

[0059] The method for obtaining the urethane resin composition having a nonionic group may, for example, be a method using one or more compounds having an oxyethylene structure as a raw material.

[0060] Examples of the compound having an oxyethylene structure that can be used include polyether polyols having an oxyethylene structure, such as polyoxyethylene glycol, polyoxyethylene polyoxypropylene glycol, polyoxyethylene polyoxytetramethylene glycol, etc. These compounds may be used alone or in combination of two or more.

[0061] Examples of emulsifiers that can be used when obtaining the urethane resin composition that is forcibly dispersed in water include nonionic emulsifiers such as polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene styrylphenyl ether, polyoxyethylene sorbitol tetraoleate, and polyoxyethylene-polyoxypropylene copolymers; anionic emulsifiers such as fatty acid salts such as sodium oleate, alkyl sulfate ester salts, alkylbenzene sulfonates, alkyl sulfosuccinates, naphthalene sulfonates, polyoxyethylene alkyl sulfates, sodium alkanesulfonates, and sodium alkyldiphenyl ether sulfonates; and cationic emulsifiers such as alkylamine salts, alkyltrimethylammonium salts, and alkyldimethylbenzylammonium salts. These emulsifiers may be used alone or in combination of two or more.

[0062] Specifically, the urethane resin composition may be, for example, a reaction product of the raw materials used for producing the urethane resin composition having a hydrophilic group, polyisocyanate (a1), polyol (a2), and, if necessary, chain extender (a3). These reactions may be performed by known urethane reactions.

[0063] Examples of the polyisocyanate (a1) include aromatic polyisocyanates such as phenylene diisocyanate, tolylene 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 may be used alone or in combination of two or more.

[0064] Examples of the polyol (a2) that can be used include polyether polyols, polyester polyols, polyacrylic polyols, polycarbonate polyols, polybutadiene polyols, etc. These polyols may be used alone or in combination of two or more kinds.

[0065] From the viewpoint of the mechanical strength of the resulting film, the number average molecular weight of the polyol (a2) is preferably in the range of 500 to 100,000, more preferably in the range of 800 to 50,000, and even more preferably in the range of 800 to 2500. The number average molecular weight of the polyol (a2) is a value measured by gel permeation column chromatography (GPC).

[0066] The chain extender (a3) ​​is, for example, one having a number average molecular weight in the range of 50 to 450. Specific examples thereof include 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, hydrazine, and the like. chain extenders having an amino group such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, hexamethylene glycol, saccharose, methylene glycol, glycerin, sorbitol, bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, trimethylolpropane, etc. These chain extenders may be used alone or in combination of two or more.

[0067] When the chain extender (a3) ​​is used, the amount used is preferably within a range of 0.5 to 30 mass % based on the total mass of the polyisocyanate (a1), the polyol (a2) and the chain extender (a3), in order to further improve the mechanical strength of the coating.

[0068] Examples of the method for producing the urethane resin water dispersion include a method in which the raw materials used to produce the urethane resin composition having a hydrophilic group are reacted with the polyisocyanate (a1), the polyol (a2), and the hydrophilic group-containing urethane prepolymer (a4) having an isocyanate group (hereinafter, sometimes abbreviated as "prepolymer step"). Then, the urethane prepolymer (a4) is dispersed in water (hereinafter, sometimes abbreviated as "emulsification step"), and if necessary, the urethane prepolymer (a4) is reacted with the chain extender (a3) ​​(hereinafter, sometimes abbreviated as "chain extension step"). And a method in which the polyisocyanate (a1), the polyol (a2), the raw materials used to produce the hydrophilic group-containing urethane resin composition, and if necessary, the chain extender (a3) ​​are charged all at once and reacted. These reactions are carried out, for example, at 50 to 100°C for 3 to 10 hours.

[0069] The prepolymerization process can also be carried out without a solvent. In the prior art, the prepolymerization process was generally carried out in an organic solvent such as methyl ethyl ketone or acetone, but a desolvation process for distilling off the organic solvent was required after the emulsification process, and this required several days of production at the actual production site. 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, in the method for producing a urethane resin aqueous dispersion according to the present invention, the prepolymerization process can be carried out without a solvent, thereby obtaining a urethane resin aqueous dispersion that is completely free of organic solvent, and the production process can also be labor-saving. The reaction in the prepolymerization process can be carried out, for example, at 50 to 120° C. for 1 to 10 hours.

[0070] The prepolymer process can be carried out using a reaction vessel equipped with an agitator; 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, a Bodeta-type kneader, or other kneading machine; a rotary dispersion mixer such as a TK Homomixer, Filmix, Ebara Milder, Clearmix, Ultra Turrax, Cavitron, or Biomixer; an ultrasonic dispersion device; or an in-line mixer or other device that has no moving parts and can mix by the flow of the fluid itself.

[0071] 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 the prepolymer step. Among them, it is preferable to use a kneader, since it is possible to stably obtain an aqueous dispersion of a urethane resin composition having a small amount of oxyethylene groups introduced and an average particle size equivalent to that of a conventional method, which is reacted with a chain extender, and it is possible to easily obtain an aqueous dispersion of a urethane resin having a high content of the urethane resin composition.

[0072] The chain extension step is a step of obtaining a urethane resin composition by increasing the molecular weight of the urethane prepolymer (a4) through a reaction between the isocyanate group of the urethane prepolymer (a4) and the chain extender (a3). From the viewpoint of productivity, the temperature during the chain extension step is preferably 50° C. or less.

[0073] In the chain extension step, the molar ratio of the isocyanate groups in the urethane prepolymer (a4) 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, and more preferably in the range of 0.9 to 1, in order to obtain even better film-forming properties and mechanical strength.

[0074] The chain extension step can be carried out using equipment similar to that of the prepolymer step.

[0075] When producing the urethane resin composition, it is preferable to deactivate the isocyanate group remaining in the urethane resin composition. When deactivating the isocyanate group, it is preferable to use an alcohol having one hydroxyl group such as methanol. The amount of the alcohol used is preferably in the range of 0.001 to 10 parts by mass relative to 100 parts by mass of the urethane resin composition.

[0076] In addition, when producing the urethane resin composition, an organic solvent may be used. As the organic solvent, for example, ketone compounds such as acetone and methyl ethyl ketone; ether compounds such as tetrahydrofuran and dioxane; acetate compounds such as ethyl acetate and butyl acetate; nitrile compounds such as acetonitrile; amide compounds such as dimethylformamide and N-methylpyrrolidone, etc. may be used. These organic solvents may be used alone or in combination of two or more kinds. It is preferable that the organic solvent is finally removed by a distillation method or the like.

[0077] (water) The water used in the present invention may be ion-exchanged water, distilled water, ultrafiltered water, ultrapure water, etc. These waters may be used alone or in combination of two or more. In addition, in order to easily prevent the growth of mold or bacteria when storing the urethane resin aqueous dispersion for a long period of time, it is preferable to use water sterilized by ultraviolet irradiation, addition of hydrogen peroxide, etc.

[0078] (Pigments) The urethane resin aqueous dispersion of the present invention preferably further contains a pigment. By containing a pigment in the surface layer forming liquid 32, the surface layer itself can be given a color pattern, eliminating the need to further form a decorative layer, and as a result, there are no problems such as ensuring adhesion between the decorative layer and the surface layer and the sheet conformability of the decorative layer coating (whether the coating cracks when folded). There is no particular limitation on the form of the pigment, and the pigment may be used alone or in combination with other components. When adding a pigment to the urethane resin water dispersion, it is preferable to add the pigment in the form of a pigment dispersion to the urethane resin water dispersion and stir or mix it, from the viewpoints of ease of production and stability of the urethane resin water dispersion.

[0079] The pigment may be an inorganic pigment or an organic pigment. Specifically, any known inorganic or organic pigment that can be dispersed in water or a water-soluble organic solvent may be used. In the present invention, it is preferable to use titanium oxide or carbon black as the pigment.

[0080] The pigment may be either a non-acid-treated pigment or an acid-treated pigment, and may be in either a dry powder or wet cake form.

[0081] Examples of inorganic pigments include iron oxide, carbon black produced by known methods such as the contact method, furnace method, thermal method, etc. In addition, oxides, hydroxides, sulfides, ferrocyanides, chromates, carbonates, silicates, phosphates, metal powders, etc. may also be used. Examples of organic pigments include dye lakes, azo lakes, insoluble azos, monoazos, disazos, condensed azos, benzimidazolones, phthalocyanines, anthraquinones, perylenes, perinone pigments, quinacridones, dioxazines, isoindolines, azomethines, thioindigo pigments, quinophthalone pigments, pyrrolopyrroles, etc. Also usable are dye chelates (e.g., basic dye chelates, acid dye chelates, etc.), nitro pigments, nitroso pigments, aniline black, etc.

[0082] Examples of the white pigment include alkaline earth metal sulfates, carbonates, fine silicic acid, synthetic silicates, and other silicates, calcium silicate, alumina, alumina hydrate, titanium oxide, zinc oxide, talc, clay, etc. The inorganic white pigment may be surface-treated by various surface treatment methods. Among these, titanium oxide is preferred.

[0083] As the black pigment, carbon black is preferable, and examples thereof include No. 2300, No. 2200B, No. 900, No. 960, No. 980, No. 33, No. 40, No. 45, No. 45L, No. 52, HCF88, MA7, MA8, MA100, etc. manufactured by Mitsubishi Chemical Corporation, Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 700, etc. manufactured by Columbia Corporation, Regal 400R, Regal 330R, Regal 660R, Mogul L, Mogul 700, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc. manufactured by Cabot Corporation, and Color Black manufactured by Degussa. These include FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, V, 1400U, Special Black 6, 5, 4, 4A, NIPEX150, NIPEX160, NIPEX170 and NIPEX180.

[0084] In addition, in order to produce synthetic leather for use in applications requiring design, such as having a pattern, the pigment may be a color pigment. Specific examples of yellow pigments include CI Pigment Yellow 1, 2, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 120, 128, 129, 138, 150, 151, 154, 155, 174, 180, and 185. Specific examples of magenta pigments include CI Pigment Red 5, 7, 12, 48(Ca), 48(Mn), 57(Ca), 57:1, 112, 122, 123, 146, 168, 176, 184, 185, 202, 209, 269, 282, and the like, and CI Pigment Violet 19, and the like. Specific examples of cyan pigments include CI Pigment Blue 1, 2, 3, 15, 15:3, 15:4, 16, 22, 60, 63, 66, and the like.

[0085] As specific examples of red pigments, one or more selected from the group consisting of CI Pigment Red 17, 49:2, 112, 149, 150, 177, 178, 179, 188, 254, 255 and 264 are suitably used.

[0086] Specific examples of orange pigments include CI Pigment Orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 63, 64, 71, 73, and 81.

[0087] Specific examples of green pigments include CI Pigment Green 7, 10, 36, 58, 59, and the like.

[0088] Specific examples of violet pigments include CI Pigment Violet 19, 23, 32, 33, 36, 38, 43, and 50.

[0089] When the pigment is carbon black, the volatile content of the carbon black is more preferably 1% or more. When the volatile content of carbon black is high as within the above range, the amount of functional groups (OH and COOH) on the carbon black surface is large, which is considered to facilitate maintaining compatibility with the urethane resin composition during film formation and to prevent particle aggregation, which is preferable. The volatile content of carbon black refers to the amount of volatilization (weight loss) when heated at 950° C. for 7 minutes, for example, and this value can be found in the product catalog or the like.

[0090] In order to ensure that the pigment is present stably in the aqueous pigment composition, it is preferable to take measures to disperse the pigment well in the water-soluble solvent and / or water that are the medium. Specifically, a preferred method is to prepare an aqueous pigment dispersion by dispersing the pigment in a water-soluble solvent and / or water together with a general-purpose pigment dispersant such as a polymer dispersant, a surfactant, or a pigment derivative using a dispersion method described below, or to process the pigment into a self-dispersing pigment that disperses and / or dissolves in a water-soluble solvent and / or water without a general-purpose pigment dispersant by bonding a dispersibility-imparting group (hydrophilic functional group and / or a salt thereof) to the surface of the pigment directly or indirectly via an alkyl group, an alkyl ether group, an aryl group, or the like, and disperses and / or dissolves in a water-soluble solvent and / or water without the use of a general-purpose pigment dispersant, and then blends the pigment into an aqueous pigment ink as a pigment dispersion. From the viewpoint of ink jet ejection properties and ensuring flexibility, it is preferable that the particle size of the pigment dispersion is small.

[0091] The pigment dispersant is not particularly limited, and known polymer dispersants, surfactants, and pigment derivatives can be used. Among the pigment dispersants, aqueous resins are preferred, and preferred examples include polyvinyl alcohols, polyvinylpyrrolidones, acrylic resins such as acrylic acid-acrylic acid ester copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-methacrylic acid-acrylic acid ester copolymers, styrene-α-methylstyrene-acrylic acid copolymers, styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymers, styrene-acrylic resins such as styrene-maleic acid copolymers, styrene-maleic anhydride copolymers, vinylnaphthalene-acrylic acid copolymers, and salts of the aqueous resins. Of course, commercially available products can also be used. Examples of commercially available products that can be used include the Ajisper PB series from Ajinomoto Fine-Techno Co., Ltd., the Disperbyk series from BYK Japan Co., Ltd., the EFKA series from BASF, the SOLSPERSE series from Lubrizol Japan Co., Ltd., and the TEGO series from Evonik. As the polymer-based dispersant, for example, the polymer pigment dispersant described in JP-A-2022-75758 can be used. More specifically, for example, the polymer dispersants described below can be suitably used. (1) A comb-structured polymeric pigment dispersant having a pigment-affinity group in the main chain and / or in a plurality of side chains and having a plurality of side chains that constitute a solvation moiety. (2) A polymeric pigment dispersant having multiple pigment affinity moieties in the main chain, each of which is made up of a pigment affinity group. (3) A linear polymer pigment dispersant having a pigment affinity portion consisting of a pigment affinity group at one end of the main chain. The above pigment dispersants may be used alone or in combination of two or more kinds. The pigment dispersant is preferably a modified carboxyl group-containing polymer.

[0092] The pigment affinity group referred to here means a functional group having a strong adsorption force to the surface of the pigment, and examples thereof include, in organosols, tertiary amino groups, quaternary ammonium groups, heterocyclic groups having a basic nitrogen atom, hydroxyl groups, and carboxyl groups; and, in hydrosols, phenyl groups, lauryl groups, stearyl groups, dodecyl groups, and oleyl groups.

[0093] When the pigment dispersant has an anionic group, the anionic group is preferably neutralized. As the basic compound for neutralizing the anionic group, any of the known and commonly used compounds can be used, for example, inorganic basic substances such as alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and organic basic compounds such as ammonia, triethylamine, and alkanolamines. The neutralization rate of the anionic group does not have to be 100% relative to the acid value of the pigment dispersant. Specifically, the neutralization rate is preferably 20% to 200%, and more preferably 80% to 150%.

[0094] (Self-dispersing pigment) The pigment may be a self-dispersing pigment that can be dispersed in a water-soluble solvent or water without using the pigment dispersant. For example, the pigment is produced by subjecting the pigment to a physical or chemical treatment to bond (graft) a dispersibility-imparting group or an active species having a dispersibility-imparting group to the surface of the pigment. Examples of the method include vacuum plasma treatment, oxidation treatment with hypohalous acid and / or hypohalous acid salt, oxidation treatment with ozone, a wet oxidation method in which the pigment surface is oxidized with an oxidizing agent in water, and a method in which a carboxyl group is bonded via a phenyl group by bonding p-aminobenzoic acid to the pigment surface. Since the aqueous ink containing the self-dispersing pigment does not need to contain the pigment dispersant, it is easy to prepare an ink with excellent ejection stability without foaming caused by the pigment dispersant. In addition, since a significant increase in viscosity caused by the pigment dispersant is suppressed, it is possible to contain a larger amount of pigment, which makes it possible to sufficiently increase the print density or makes the ink easier to handle.

[0095] It is also possible to use commercially available products as self-dispersing pigments. Examples of such commercially available products include Microjet CW-1 (product name; manufactured by Orient Chemical Industries, Ltd.), CAB-O-JET200, and CAB-O-JET300 (all product names; manufactured by CABOT Corporation).

[0096] (Method of manufacturing pigment dispersion) The method for producing a pigment dispersion using a pigment dispersant is not particularly limited and may be a known method. For example, the pigment, pigment dispersant, water, and various additives as necessary are stirred and mixed, and then dispersed and milled using various dispersing machines or milling machines, such as a bead mill, ultrasonic homogenizer, high-pressure homogenizer, paint shaker, ball mill, roll mill, sand mill, sand grinder, Dyno Mill, Dispermat, SC Mill, Nanomizer, etc., and the remaining materials are added and mixed to adjust the viscosity to an appropriate level. Alternatively, the dispersion liquid can be prepared by adding a water-soluble solvent and / or water and, if necessary, various additives to a high-concentration dispersion liquid (mill base) prepared in advance using the disperser, and diluting the mixture by mixing and stirring to the desired viscosity.

[0097] Self-dispersing pigments may be commercially available as aqueous pigment dispersions, or a pigment dispersion can be obtained by adding the self-dispersing pigment to water or a water-soluble solvent and stirring.

[0098] From the viewpoint of inkjet dischargeability and dispersion stability, the particle diameter of the pigment dispersion liquid is preferably such that the 95% particle diameter (D95) in the cumulative particle size distribution of the pigment is 1000 nm or less. When the 95% particle diameter (D95) in the cumulative particle size distribution of the pigment is in the above range, the pigment particle diameter can be prevented from becoming too large, the occurrence of aggregates can be suppressed, and the dispersion stability and inkjet dischargeability can be favorably maintained. The particle size of the pigment dispersion can be obtained by diluting 0.2 g of the pigment dispersion by adding 50 g of water, pretreating it with an ultrasonic homogenizer (ULTRA HOMOGENIZER US-300E, manufactured by Nippon Seiki Seisakusho) at 2.5 A for 1 minute, and measuring the particle size distribution with a dynamic light scattering device, Nanotrac WaveII, manufactured by Microtrack-Bell Corporation.

[0099] (Other Ingredients) The urethane resin water dispersion of the present invention may further contain, in addition to the above-mentioned urethane resin composition, water, and pigment, a water-soluble solvent, a surfactant, and other additives, as necessary, in order to adjust the physical properties so as to enable inkjet ejection.

[0100] Examples of other additives that can be used include emulsifiers, neutralizing agents, thickeners, urethane catalysts, fillers, flame retardants, leveling agents, antiblocking agents, film-forming assistants, defoamers, foaming agents, preservatives, pH adjusters, chelating agents, antioxidants, ultraviolet absorbers, plasticizers, etc. These additives may be used alone or in combination of two or more.

[0101] (Water-soluble solvent) The urethane resin aqueous dispersion may contain not only water but also a water-soluble solvent, and the viscosity and surface tension of the urethane resin aqueous dispersion can be adjusted to a range that allows inkjet ejection. For example, ketones such as acetone, methyl ethyl ketone, methyl butyl ketone, and methyl isobutyl ketone; alcohols such as methanol, ethanol, 2-propanol, 2-methyl-1-propanol, 1-butanol, and 2-methoxyethanol; ethers such as tetrahydrofuran, 1,4-dioxane, and 1,2-dimethoxyethane; glycols such as dimethylformamide, N-methylpyrrolidone, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol; diols such as butanediol, pentanediol, hexanediol, and diols of the same group; and glycosyl esters such as propylene glycol laurate. Examples of suitable water-soluble organic solvents include alcohol esters, glycol ethers such as cellosolves including diethylene glycol monoethyl, diethylene glycol monobutyl, and diethylene glycol monohexyl ethers, propylene glycol ether, dipropylene glycol ether, and triethylene glycol ether, alcohols such as methanol, ethanol, isopropyl alcohol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, butyl alcohol, pentyl alcohol, and alcohols of the same family as these, and also sulfolane, lactones such as γ-butyrolactone, lactams such as N-(2-hydroxyethyl)pyrrolidone, and various other solvents known as water-soluble organic solvents, such as glycerin and its derivatives. These water-soluble organic solvents can be used alone or in combination of two or more.

[0102] In addition, the water-soluble organic solvent used at this time is preferably a water-soluble organic solvent having a high boiling point, since there is no need for desolvation in a later step. Examples of such water-soluble organic solvents having a high boiling point include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol; diols such as butanediol, pentanediol, hexanediol, and diols of the same group; glycol esters such as propylene glycol laurate; glycol ethers such as cellosolve containing diethylene glycol monoethyl, diethylene glycol monobutyl, and diethylene glycol monohexyl ethers, propylene glycol ether, dipropylene glycol ether, and triethylene glycol ether; sulfolane; lactones such as γ-butyrolactone; lactams such as N-(2-hydroxyethyl)pyrrolidone; and glycerin and its derivatives, and other various solvents known as water-soluble organic solvents. These water-soluble organic solvents can be used alone or in combination of two or more.

[0103] In order to improve the ink-jet ejection properties, it is preferable to use a water-soluble organic solvent as a wetting agent in the urethane resin aqueous dispersion so that the urethane resin aqueous dispersion is less likely to dry out in the nozzles of the ink-jet head. Examples of such wetting agents include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycols having a molecular weight of 2000 or less, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propylene glycol, isopropylene glycol, isobutylene glycol, 1,2-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, It is more preferable to use diol compounds such as 1,2-hexanediol, 1,6-hexanediol, 2-methylpentane-2,4-diol, 1,2-heptanediol, 1,2-nonanediol, 1,2-octanediol, 1,2-hexanediol, 1,2-heptanediol, 1,2-nonanediol, and 1,2-octanediol, and nitrogen-containing heterocyclic compounds such as 1,4-butanediol, 1,3-butanediol, mesoerythritol, pentaerythritol, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, and ε-caprolactam. Among them, it is more preferable to use propylene glycol, ethylene glycol, and glycerin, which are safe and have excellent effects on drying properties and ejection performance in the nozzle. The content of the wetting agent in the urethane resin aqueous dispersion is preferably 3 to 50% by mass.

[0104] (Surfactant) A surfactant may be added to the urethane resin aqueous dispersion in order to adjust the surface tension or to control the wettability of the urethane resin aqueous dispersion to the fibrous substrate after extrusion. Examples of the surfactant include anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc., and among these, anionic surfactants or nonionic surfactants are preferred.

[0105] Examples of the anionic surfactant include alkylbenzenesulfonates, alkylphenylsulfonates, alkylnaphthalenesulfonates, higher fatty acid salts, sulfate ester salts of higher fatty acid esters, sulfonates of higher fatty acid esters, sulfate ester salts and sulfonates of higher alcohol ethers, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, and polyoxyethylene alkyl ether phosphates. Specific examples of these include dodecylbenzenesulfonates, isopropylnaphthalenesulfonates, monobutylphenylphenol monosulfonates, monobutylbiphenylsulfonates, and dibutylphenylphenol disulfonates.

[0106] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene glycerin fatty acid esters, polyglycerin fatty acid esters, sucrose fatty acid esters, polyoxyethylene alkylamines, polyoxyethylene fatty acid amides, fatty acid alkylol amides, alkyl alkanol amides, acetylene glycol, oxyethylene adducts of acetylene glycol, polyethylene glycol polypropylene glycol block copolymers, and alkylphenol ethoxylates. Of these, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid alkylol amides, acetylene glycol, oxyethylene adducts of acetylene glycol, polyethylene glycol polypropylene glycol block copolymers, and alkylphenol ethoxylates are preferred.

[0107] Other surfactants that can be used include silicon-based surfactants such as polysiloxane oxyethylene adducts; fluorine-based surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers; and biosurfactants such as spiculisporic acid, rhamnolipids, and lysolecithin.

[0108] These surfactants can be used alone or in combination of two or more. In consideration of the dissolution stability of the surfactant, the HLB value is preferably in the range of 7 to 20.

[0109] Commercially available fluorine-based surfactants include Novec FC-4430, FC-4432 (all manufactured by Sumitomo 3M), Zonyl FSO-100, FSN-100, FS-300, FSO (all manufactured by DuPont), F-Top EF-122A, EF-351, 352801, 802 (manufactured by Gemco), Megafac F-470, F-1405, F474, F-444 (manufactured by DIC), Surflon S-111, S-112, S-113, S Examples of suitable fluororesin include S121, S131, S132, S-141, S-145 (manufactured by Asahi Glass), Ftergent series (manufactured by Neos), Fluorad FC series (manufactured by Minnesota Mining and Manufacturing Company), Monflor (manufactured by Imperial Chemical Industries), and Licowet VPF series (manufactured by Farbewerke-Hoechst).

[0110] Examples of silicone surfactants include KF-351A, KF-642, Olfin PD-501, Olfin PD-502, Olfin PD-570 (manufactured by Shin-Etsu Chemical Co., Ltd.), BYK347, and BYK348 (manufactured by BYK Japan).

[0111] Examples of polyoxyethylene alkyl ether surfactants include the BT series (Nikko Chemicals), the Nonipol series (Sanyo Chemical), the D-, P-series (Takemoto Oil & Fat), the EMALEXDAPE series (Nippon Emulsion), and the Pegnol series (Toho Chemical Industry Co., Ltd.). Examples of polyethylene glycol alkyl ester surfactants include Pegnol (Toho Chemical Industry Co., Ltd.). Examples of acetylene glycol surfactants include Olfine E1010, STG, and Y (all manufactured by Nissin Chemical Co., Ltd.), and Surfynol 104, 82, 420, 440, 465, 485, and TG (manufactured by Air Products and Chemicals Inc.).

[0112] The viscosity of the urethane resin water dispersion is not particularly limited, but it is preferably a viscosity that allows it to be ejected by inkjet, and the ejection viscosity (for example, when adjusted to 25°C with a temperature regulator, the viscosity at 25°C) is preferably 5 to 500 mPa s, more preferably 8 to 200 mPa s, and even more preferably 8 to 100 mPa s.

[0113] The surface tension of the urethane resin water dispersion is not particularly limited, but is preferably such that it can be ejected by inkjet, and is preferably 15 to 50 mN / m at 25°C, and more preferably 20 to 40 mN / m.

[0114] (Active energy ray curable paint) The surface layer forming liquid 32 may be an active energy ray curable paint containing urethane acrylate. The urethane acrylate is a (meth)acrylate having a urethane bond in the molecule. For example, a compound obtained by reacting a polyol, a polyisocyanate, and a (meth)acrylic compound having a hydroxyl group or an isocyanate group by a conventionally known method can be used. In the present invention, the term "(meth)acrylate" refers to either or both of an acrylate and a methacrylate, and the term "(meth)acryloyl group" refers to either or both of an acryloyl group and a methacryloyl group.

[0115] Examples of the polyol that can be used include polyester polyol, polycarbonate polyol, polyether polyol, acrylic polyol, caprolactone polyol, butadiene polyol, etc. These polyols may be used alone or in combination of two or more kinds.

[0116] Examples of the polyisocyanate include aromatic diisocyanates such as phenylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, and naphthalene diisocyanate; aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate; and aromatic polyisocyanates such as xylylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, phenylene diisocyanate, polyphenylene polymethylene polyisocyanate, formalin condensate of methylene diphenyl diisocyanate, and carbodiimide modified product of 4,4'-diphenylmethane diisocyanate. These polyisocyanates may be used alone or in combination of two or more.

[0117] Examples of the (meth)acrylic compound having a hydroxyl group that can be used include (meth)acrylic acid alkyl esters having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, etc. These compounds may be used alone or in combination of two or more.

[0118] Examples of the (meth)acrylic compound having an isocyanate group that can be used include 2-(meth)acryloyloxyethyl isocyanate, 2-(2-(meth)acryloyloxyethyloxy)ethyl isocyanate, 1,1-bis((meth)acryloyloxymethyl)ethyl isocyanate, etc. These compounds may be used alone or in combination of two or more.

[0119] The active energy ray-curable coating material containing a urethane acrylate preferably contains a polymerizable compound other than the above-mentioned urethane acrylate. The other polymerizable compound is not particularly limited as long as it can reproduce the texture of synthetic leather as a surface layer, but it is preferable to use a polymerizable compound with a low viscosity in order to adjust the viscosity to a level suitable for inkjet ejection. In addition, it is more preferable to use a monofunctional monomer and a multifunctional monomer in combination in order to obtain flexibility of the surface layer.

[0120] It is preferable that the active energy ray curable paint containing urethane acrylate further contains a pigment. When the surface layer forming liquid 32 contains a pigment, the surface layer itself can be given a color pattern, and therefore it is not necessary to further form a decorative layer. The pigment is not particularly limited, and any suitable one of the above pigments can be used. The pigment may be dispersed by a pigment dispersant. The above-mentioned polymer dispersant or a surfactant can be used as the pigment dispersant.

[0121] Other additives may be added to the active energy ray-curable coating material containing urethane acrylate. The other additives may include a photopolymerization initiator, a photosensitizer, a polymerization inhibitor, an ultraviolet absorber, an antioxidant, a surface tension adjuster, and a discoloration inhibitor.

[0122] The viscosity of the active energy ray-curable coating material containing a urethane acrylate is not particularly limited, but it is preferably a viscosity that allows inkjet ejection, and the ejection viscosity (for example, the viscosity at 25°C when adjusted to 25°C with a temperature regulator) is preferably 5 to 500 mPa·s, more preferably 8 to 200 mPa·s, and even more preferably 8 to 100 mPa·s.

[0123] The surface tension of the active energy ray-curable coating material containing urethane acrylate is not particularly limited, but is preferably a surface tension that allows inkjet ejection, and is preferably 15 to 50 mN / m, and more preferably 20 to 40 mN / m at 25°C.

[0124] (fibrous base material) The fibrous base material 100 is also called a base fabric, and a skin layer 130 can be formed on the fibrous base material 100 to obtain synthetic leather 150. Alternatively, a primer layer 110 and / or an intermediate layer 120 can be formed on the fibrous base material 100 as necessary to form a base material, on which the skin layer 130 can be formed. Examples of materials for the fibrous base material 100 include, but are not limited to, natural fibers (plant fibers / animal fibers) such as cotton, linen, and silk; and chemical fibers such as polyester, nylon, acrylic, and polyurethane. Examples of the form of the fibrous base material 100 include, but are not limited to, knitted fabric, woven fabric, nonwoven fabric, and the like.

[0125] (Adhesive layer) The fibrous substrate may be provided with an adhesive layer to improve the interlayer adhesion between layers above and below the adhesive layer (e.g., between the fibrous substrate and a surface layer, between the fibrous substrate and an intermediate layer, etc.). The adhesive layer is preferably formed from a urethane resin composition containing water and a urethane resin made from an aromatic polyisocyanate, which has high intermolecular interactions. By using a urethane resin made from an aromatic polyisocyanate, which has high intermolecular interactions, in the adhesive layer, excellent peel strength and chemical resistance can be obtained.

[0126] The adhesive layer may contain other additives, such as urethane catalysts, neutralizing agents, crosslinking agents, silane coupling agents, thickeners, fillers, thixotropic agents, tackifiers, waxes, heat stabilizers, light resistance stabilizers, fluorescent brighteners, foaming agents, pigments, dyes, conductivity-imparting agents, antistatic agents, moisture permeability enhancers, water repellents, oil repellents, hollow foams, flame retardants, water absorbents, moisture absorbents, deodorants, foam stabilizers, antiblocking agents, hydrolysis inhibitors, etc. These additives may be used alone or in combination of two or more.

[0127] The thickness of the adhesive layer is appropriately determined depending on the application of the synthetic leather, and may be, for example, in the range of 5 to 100 μm.

[0128] (Step of forming surface treatment layer) The method for producing a synthetic leather of the present invention may further include a step of forming a surface treatment layer on the surface of the above-mentioned skin layer using a surface treatment agent. The surface treatment layer is added for the purpose of improving scratch resistance, light resistance, texture, etc. The surface treatment layer may also be formed for the purpose of imparting antibacterial properties, flame retardancy, etc. The step of forming the surface treatment layer may be a step of forming it by an inkjet method like the skin layer, or a step of forming it by gravure roll coating, comma roll coating or the like like a conventional method.

[0129] (Surface treatment agent) The surface treatment agent is not particularly limited, and known ones can be used. For example, it may be a solvent-based resin composition, may contain a polyurethane water dispersion and an ultraviolet absorbing polymer, may contain a urethane resin composition and a crosslinking agent, may contain a filler to impart a matte feel, may contain an antibacterial agent, a flame retardant, etc. The materials used in conventional surface treatment agents were mainly solvent-based resin compositions containing organic solvents, but in response to the increasing environmental regulations in recent years, it is preferable to use an aqueous surface treatment agent that does not substantially contain organic solvents.

[0130] FIG. 2 is a schematic diagram of a preferred embodiment of the manufacturing method of the present invention. First, the fibrous substrate 100 is conveyed from the substrate roll 70 in the same manner as in FIG. 1. In the primer layer forming step, a primer liquid 12 is discharged from the inkjet head 11 for the primer layer installed at the destination of the fibrous substrate 100, and is dried in a primer dryer 13. Then, in the intermediate layer forming step, an intermediate layer forming liquid 22 is discharged from the inkjet head 21 for the intermediate layer, and is dried in a dryer for the intermediate layer. Such an intermediate layer forming step may be performed only once, or may be performed two or more times to obtain a required film thickness. FIG. 2 shows an example in which the intermediate layer is formed twice. Then, the intermediate layer thickness meter 24 is used to confirm that the film thickness is an arbitrary thickness. Furthermore, the skin layer forming step is performed in the same manner as in FIG. 1, and the synthetic leather 150 is wound up on the product winding roll 80 via the guide roll 50 as necessary.

[0131] (Primer layer) The primer layer is added to improve the adhesion between the layers by sandwiching them between the layers. The primer liquid for forming the primer layer is not particularly limited as long as it can achieve the purpose, and the adhesion between the layers may be improved by a liquid containing a highly adhesive resin or the like, or the adhesion between the layers may be improved by an anchor effect by improving the permeability of the liquid used in the upper layer of the primer layer by a liquid that enhances wettability, or the fixability may be improved by quickly coagulating the liquid used in the upper layer.

[0132] The primer liquid is not particularly limited, but may be, for example, a metal salt solution such as a cationic pretreatment agent such as calcium nitrate, calcium chloride, zinc nitrate, zinc chloride, magnesium acetate, aluminum sulfate, or sodium chloride, or a cationic polymer solution containing ammonium ions.

[0133] The applied primer liquid is preferably subjected to a drying step using a dryer 13 before proceeding to the next step. The dryer 13 used in the drying step is not particularly limited, and drying can be appropriately performed using equipment similar to that used for the surface layer.

[0134] (Middle class) The intermediate layer is added to impart a high-quality texture and a soft feel to the synthetic leather 150. The intermediate layer is preferably formed by in-line inkjet coating of the intermediate layer forming liquid 22 on the fibrous substrate, but may be applied in-line using a roll coater, knife coater, comma coater, or the like, or a laminate in which the intermediate layer is separately formed on the fibrous substrate offline may be used as the fibrous substrate 100.

[0135] The intermediate layer is preferably formed of urethane foam. The urethane foam may be produced by foaming an aqueous urethane resin dispersion for the intermediate layer, which is prepared by dispersing a urethane resin in water with a surfactant, to obtain a foamed liquid, and applying the foamed liquid to the fibrous substrate 100 or a substrate having a primer layer as the intermediate layer forming liquid 22, and drying it as necessary to obtain a desired density. In addition, an aqueous urethane resin dispersion containing a foaming agent may be used as the intermediate layer forming liquid 22, or an aqueous urethane resin dispersion containing a volatile solvent, a liquefied gas, hollow spheres, etc. may be used as the intermediate layer forming liquid 22, and a publicly known foaming method may be used.

[0136] Examples of methods for foaming the urethane resin aqueous dispersion for intermediate layer to obtain a foamed liquid include manual stirring and using a mixer such as a mechanical mixer. When using a mixer, examples include stirring at 500 to 3,000 rpm for 10 seconds to 3 minutes. In this case, in order to easily adjust the density of the foamed urethane to a preferred range, the volume is preferably 1.3 to 7 times, more preferably 1.3 to 2 times, and even more preferably 1.3 to 1.7 times, of the volume before and after foaming.

[0137] The inkjet method is preferred as a method for applying the intermediate layer forming liquid 22 to the fibrous substrate 100 or a substrate having a primer layer 110. When a foaming liquid is used as the intermediate layer forming liquid 22, the application may be carried out by a method using, for example, a roll coater, a knife coater, a comma coater, an applicator, or the like. Application to the substrate may also be carried out in-line.

[0138] It is preferable to have an intermediate layer drying step after applying the intermediate layer forming liquid 22. The drying step is not particularly limited, and drying can be performed under appropriate conditions using the same equipment as for the surface layer.

[0139] The density of the urethane foam is preferably 200 to 1,000 kg / m from the viewpoint of obtaining a more preferable texture and tensile strength. 3 is preferably 300 to 900 kg / m 3 More preferably, the range is 400 to 800 kg / m 3 The density of the urethane foam is a value calculated by dividing the mass of the urethane foam by its volume.

[0140] The intermediate layer made of urethane foam may be formed by a conventional method. Specifically, a urethane resin composition containing an organic solvent is applied to a fibrous substrate or the like, and then the substrate is immersed in water, whereby the solvent in the urethane resin composition is replaced with water, and the solid matter in the urethane resin composition precipitates to form a film. Next, the remaining solvent is thoroughly washed away with water, and the substrate is squeezed with a mangle roll or the like, and then dried to obtain a laminate in which an intermediate layer made of urethane foam is laminated on a fibrous substrate or the like. The laminate may be used as a substrate, and a surface layer may be formed on the intermediate layer by an inkjet method to obtain synthetic leather. When a laminate having an intermediate layer is produced by the above method, a wet film-forming aid may be appropriately blended into the urethane resin composition of the present invention in order to adjust the film-forming speed and to obtain good surface smoothness. Examples of the wet film-forming aid include castor oil, glycerin tripalmitate, and silicone oil. These wet film-forming aids may be used alone or in combination of two or more.

[0141] The thickness of the intermediate layer 120 is preferably in the range of, for example, 0.1 to 500 μm. When the intermediate layer 120 is formed in-line, it is preferable to measure the film thickness with an intermediate layer film thickness meter 24 and adjust the application amount of the intermediate layer forming liquid 22 after the intermediate layer forming step and, if necessary, the drying step.

[0142] The synthetic leather produced by the synthetic leather production method of the present invention does not require release paper, and CO2 emissions during the production process are significantly reduced compared to conventional production methods, making it possible to reduce the environmental impact. Also, unlike conventional production methods, each process can be carried out in-line, leading to improved production efficiency through automation. Furthermore, by forming each layer using the inkjet method, the amount of waste liquid in all processes, including cleaning, can be reduced, a decoration process is not required, small-scale production is easy, and on-demand response to demand is possible.

[0143] Fig. 4 is a schematic diagram showing another embodiment of the synthetic leather obtained by the method for producing synthetic leather of the present invention, but the present invention is not limited thereto. In addition, the synthetic leather is partially cut to expose the cushioning material inside. The synthetic leathers 201 and 202 obtained by the manufacturing method of the present invention include surface layers 221 and 222. Moreover, the synthetic leathers 201 and 202 are preferably obtained by laminating the surface layers 221 and 222 on cushioning materials 211 and 212 made of urethane foam or the like corresponding to the base material. Moreover, another layer may be included between the cushioning materials 211 and 212 and the surface layers 221 and 222. Moreover, although not shown in FIG. 4, the synthetic leathers 201 and 202 may further have a surface treatment layer on the surface layers 221 and 222. The skin layers typified by the skin layers 221 and 222 have a function of reproducing the texture of natural leather, similar to the above-mentioned skin layer 130. In the present invention, the skin layer is formed by an inkjet method, and is similar to the above-mentioned skin layer 130, and the preferred embodiments are also similar.

[0144] The method for producing the cushioning material made of urethane foam or the like is not particularly limited, and it can be produced by a publicly known method, for example, by injecting a foaming raw material such as urethane foam into a mold and allowing it to foam. The cushion material serving as the base material may include a skeleton frame, a connecting shaft, an airbag, an air cell, an air supply tube, a fluid cell, a fluid supply tube, a seat heater, a lumbar support portion, a pressure sensor, a position adjustment mechanism, etc. Also, it may be a laminate of a pre-treatment layer, an intermediate layer, a seat cover pad layer, a wadding layer, a pleated pad layer, etc. Furthermore, the cushion material may be, for example, a seating sheet and a backrest sheet integrated together, or a seating sheet and a lumbar support portion separated from each other, and the shape of the cushion material is not particularly limited, and may be a suitable shape depending on the application.

[0145] The synthetic leather 201 may be, for example, a seat for a seating portion of a vehicle, and the synthetic leather 202 may be, for example, a seat for a backrest of a vehicle. Similarly to the synthetic leathers 201 and 202, the synthetic leather 203 may also be a synthetic leather having a skin layer, and may be, for example, a headrest. Then, by assembling these synthetic leathers 201, 202, and 203, the vehicle seat 200 may be manufactured.

[0146] FIG. 5 is a schematic diagram showing one embodiment of the manufacturing method of the present invention. First, a cushion material 212 made of urethane foam or the like is placed under the inkjet head 31. The cushion material 212 is a three-dimensional object, and the cushion material 212 and the inkjet head 31 do not need to be placed downward in the direction of gravity. As long as the cushion material 212 is positioned in the direction of the nozzle surface of the inkjet head 31, they may be arranged side by side or upside down. There is no particular limitation on the method of transporting the cushion material 212. The cushion material 212 may be sent under the inkjet head 31 fixed by a belt conveyer or the like, or the inkjet head 31 may be brought close to a place where the cushion material 212 is fixed by a support rod or the like by an arm 300 (only a part of which is shown) holding the inkjet head 31 or the like. The arm 300 may be movable in one dimension, two dimensions, or three dimensions. Furthermore, the inkjet head 31 may be a single movable head, or multiple inkjet heads 31 may be fixed to a carriage or arm 300, or multiple arms 300 with one inkjet head 31 fixed thereto may be used.

[0147] Thereafter, the epidermis layer forming liquid 32 is discharged from the inkjet head 31 and dried by a dryer or the like as necessary. Drying may be performed simultaneously with inkjet discharge as long as drying of the inkjet head 31 can be suppressed. The skin layer forming liquid 32 is discharged while changing the position of the inkjet head 31 and the cushion material 212 as necessary, and a uniform skin layer 222 is formed on the cushion material 212, thereby producing synthetic leather 202 to be used as a seat for the backrest of a vehicle. There are no particular limitations on the method for changing the position of the inkjet head 31 and the cushion material 212, and for example, a stage or support rod to which the cushion material 212 is fixed may be one that rotates, or a carriage or arm 300 to which the inkjet head 31 is fixed may be one that is movable.

[0148] In addition, another layer (e.g., a primer layer, an intermediate layer, a seat cover pad layer, a wadding layer, a pleat pad layer, a surface treatment layer, etc.) may be laminated between or on top of the surface layer 222 and the cushioning material 212, and the lamination method is not particularly limited, and may be spray painting, dip coating, or inkjet coating similar to that for the surface layer.

[0149] The step of forming the epidermis layer by the inkjet method is the same as the epidermis layer forming step in Fig. 1, and the preferred embodiments are also the same. The inkjet head 31 and the epidermis layer forming liquid 32 can also be the same as the inkjet head and the epidermis layer forming liquid described above. The steps of forming the other layers, the drying steps, etc. are also the same as the methods described above, and the preferred embodiments are also the same.

[0150] At the end of the process of forming the skin layer by the inkjet method, it is preferable to install a thickness meter in order to control the thickness of the skin layer. The thickness meter is not particularly limited, and a known one can be used, for example, an electromagnetic thickness meter, an eddy current thickness meter, an ultrasonic thickness meter, a reflection spectroscopic thickness meter, a fluorescent X-ray thickness meter, etc. can be used. It is preferable to use a reflection spectroscopic thickness meter, a fluorescent X-ray thickness meter, etc., which are non-contact thickness meters advantageous for in-line measurement. However, if in-line measurement is not performed, the film thickness can also be determined from cross-sectional photographs of the synthetic leather taken with an electron microscope. Any method that can determine the film thickness can be applied, and there are no particular limitations.

[0151] By producing synthetic leather using the production method of the present invention, it is possible to eliminate the synthetic leather sheet production process and the sewing process, which were previously required to produce a synthetic leather sheet and then sew it and cover it with a cushioning material, and it is possible to reduce overall CO2 emissions in the production of vehicle seats, etc. Furthermore, the production of vehicle seats, etc. can be fully automated, making it easy to produce small quantities and the right amount at the right time.

[0152] (Synthetic leather manufacturing equipment) The present invention further provides an apparatus for producing synthetic leather, which comprises a substrate transport means, an inkjet head, and a dryer, and forms a skin layer by an inkjet method. The apparatus can significantly reduce the number of processes and reduce waste liquid and waste materials (such as release paper) including those in the cleaning process.

[0153] Here, the substrate transport means in the manufacturing apparatus may be realized by the substrate roll 70 and the product winding roll 80 in Fig. 1, or may be other means. The inkjet head corresponds to the skin layer inkjet head 31 in Fig. 1. The dryer may be the same as the skin layer dryer 33 in Fig. 1.

[0154] The production apparatus of the present invention may further include a film thickness measuring means, an intermediate layer foaming means, and other devices.

[0155] The present invention also provides a synthetic leather manufacturing device that includes an inkjet head moving means, an inkjet head, and a dryer, and forms a skin layer by an inkjet method. This manufacturing device can significantly reduce the number of processes and reduce waste liquid and waste materials (cut scraps, etc.) including the washing process.

[0156] Here, the inkjet head moving means in the manufacturing apparatus may be realized by a carriage or arm 300 to which the inkjet head is fixed, or may be other means. The inkjet head corresponds to the epidermal layer inkjet head 31 in Fig. 5. Furthermore, the dryer may be the same as the epidermal layer dryer 33 described above. EXAMPLES

[0157] Hereinafter, one embodiment of the present invention will be described in more detail using examples.

[0158] (Production Example 1: Preparation of urethane resin water dispersion (A-1)) In a nitrogen-substituted container equipped with a thermometer, a reflux condenser, a nitrogen gas inlet tube, and a stirrer, 1,000 parts by mass of polycarbonate polyol (made from 1,6-hexanediol, number average molecular weight: 2,000), 67 parts by mass of 2,2-dimethylolpropionic acid, and 710 parts by mass of methyl ethyl ketone were added under a nitrogen stream and mixed uniformly. After that, 590 parts by mass of dicyclohexylmethane diisocyanate was added, followed by 0.1 parts by mass of stannous octoate, and the mixture was allowed to react at 70°C for approximately 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having an isocyanate group at the molecular end. Next, 51 parts by mass of triethylamine was added to the methyl ethyl ketone solution of the urethane prepolymer obtained above to neutralize the carboxyl group in the urethane prepolymer, and then 1555 parts by mass of ion-exchanged water was added, and then 128 parts by mass of isophorone diamine was added and reacted. After the reaction was completed, methyl ethyl ketone was removed under reduced pressure at a temperature of 40°C to 60°C, and water was added to adjust the concentration, thereby obtaining a urethane resin water dispersion (A-1) with a non-volatile content of 35% by mass.

[0159] (Production Example 2: Preparation of urethane resin aqueous dispersion (A-2)) In a nitrogen-substituted container equipped with a thermometer, a reflux condenser, a nitrogen gas inlet tube, and a stirrer, 500 parts by mass of polyoxytetramethylene glycol (number average molecular weight: 1,000), 28.2 parts by mass of 2,2-dimethylolpropionic acid, and 436 parts by mass of methyl ethyl ketone were added under a nitrogen stream and mixed uniformly, after which 133.8 parts by mass of isophorone diisocyanate was added and the mixture was allowed to react at 80°C for approximately 3 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having an isocyanate group at the molecular end. Next, 14.3 parts by mass of 25% aqueous ammonia was added to the methyl ethyl ketone solution of the urethane prepolymer obtained above, and the carboxyl group in the urethane prepolymer was neutralized, and then 1504 parts by mass of ion-exchanged water was added, and then 1.1 parts by mass of hydrazine was added to react. After the reaction was completed, methyl ethyl ketone was removed under reduced pressure at a temperature of 40°C to 60°C, and water was added to adjust the concentration, thereby obtaining a urethane resin aqueous dispersion (A-2) with a non-volatile content of 23% by mass.

[0160] (Production Example 3: Preparation of Water-Based Black Pigment Dispersion (B-1)) FLOWLEN GW-1500 (12 parts by weight) manufactured by Kyoeisha Chemical Co., Ltd. was added to water (58 parts by weight), stirred for 5 minutes with a Homo Disper, and then carbon black #45 (30 parts by weight) manufactured by Mitsubishi Chemical Corporation was added while stirring, and stirred for 30 minutes. 100 g of the thus obtained blend and 100 g of 2 mm diameter glass beads were placed in a 220 cc glass bottle, and dispersed for 120 minutes with a paint conditioner (PAINT SHAKER manufactured by Toyo Seiki Co., Ltd.) to obtain an aqueous black pigment dispersion (B-1).

[0161] (Production Example 4: Preparation of Water-Based White Pigment Dispersion (B-2)) Kyoeisha Chemical Co., Ltd.'s FLOWRENE GW-1500 (6 parts by weight) was added to water (29 parts by weight), stirred for 5 minutes with a Homo Disper, and Chemours Inc.'s titanium oxide Ti-Pure TS-6200 (65 parts by weight) was added while stirring, and stirred for 30 minutes. 100 g of the resulting blend and 100 g of 2 mm diameter glass beads were placed in a 220 cc glass bottle, and dispersed for 120 minutes with a paint conditioner (Toyo Seiki Co., Ltd.'s PAINT SHAKER) to obtain an aqueous white pigment dispersion (B-2).

[0162] (Production Example 5: Preparation of Water-Based Adhesive Layer Coating) To the urethane resin Hydran WLA-515AR (DIC) (100 parts by mass), the thickener Borchi Gel 0626 (Borchers) was added while stirring with a homodisper until the viscosity reached about 6,000 mPa s. Then, the crosslinker BAYHYDUR XP2655 (Covestro) (8 parts by mass) was added and stirred for 10 minutes to produce a water-based adhesive layer paint.

[0163] (Production Example 6: Preparation of Skin Layer Forming Liquid, Black (C-1)) 30% by mass of urethane resin water dispersion (A-1) and 5% by mass of urethane resin water dispersion (A-2) were added to 38.98% by mass of water, and while stirring with a homodisper, 6% by mass of propylene glycol, 12% by mass of ethylene glycol, 0.05% by mass of preservative ACTICIDE B-20 (manufactured by Soh Japan), and 1.3% by mass of surfactant Surfynol 440 (manufactured by Nissin Chemical Industry Co., Ltd.) were added in that order and stirred for 5 minutes, after which 6.67% by mass of aqueous black pigment dispersion (B-1) was added and mixed. Finally, the mixture was filtered with a syringe filter with a pore size of 10 μm to obtain a skin layer forming liquid, black (C-1).

[0164] (Production Example 7: Preparation of epidermal layer forming solution, white (C-2)) 45% by mass of urethane resin aqueous dispersion (A-1) was added to 28.15% by mass of water, and while stirring with a homodisper, 12% by mass of ethylene glycol, 0.05% by mass of preservative ACTICIDE B-20 (manufactured by Soh Japan), and 0.6% by mass of surfactant Surfynol 440 (manufactured by Nissin Chemical Industry Co., Ltd.) were added in that order and stirred for 5 minutes, and finally 14.2% by mass of aqueous white pigment dispersion (B-2) was added and mixed. Finally, the mixture was filtered with a syringe filter with a pore size of 10 μm to obtain a surface layer forming liquid - white (C-2).

[0165] (Production Example 8: Preparation of black paint for forming skin layer (C-3)) 20 g of water-based black pigment dispersion (B-1) was added to 100 g of urethane resin water dispersion (A-1) while stirring with a homodisper. 0.1 g of leveling agent BYK-3455 (manufactured by BYK Japan Co., Ltd.) and 0.1 g of defoamer BYK-093 (manufactured by BYK Japan Co., Ltd.) were then added, and thickener ADEKA NOL UH-420 (manufactured by ADEKA Corporation) was added to bring the viscosity to about 3,000 mPa·s. The mixture was then stirred for 10 minutes to produce black paint for forming the surface layer (C-3).

[0166] (Production Example 9: Preparation of white paint for forming skin layer (C-4)) 30 g of water-based white pigment dispersion (B-2) was added to 100 g of urethane resin water dispersion (A-1) while stirring with a homodisper. 0.1 g of leveling agent BYK-3455 (manufactured by BYK Japan Co., Ltd.) and 0.1 g of defoamer BYK-093 (manufactured by BYK Japan Co., Ltd.) were then added, and thickener ADEKA NOL UH-420 (manufactured by ADEKA Corporation) was added to bring the viscosity to about 3,000 mPa·s. After that, the mixture was stirred for 10 minutes to prepare white paint for forming the surface layer (C-4).

[0167] (Example 1: Preparation of synthetic leather 1) The nonwoven fabric was immersed in a coagulant (aqueous solution of 5% by mass of calcium nitrate) for 10 seconds, and then dried to prevent penetration. The aqueous adhesive layer paint was applied to the nonwoven fabric using a knife coater to a thickness of 150 μm, and then dried using a hot air dryer (90-100°C x 3 minutes). Next, the black liquid for forming the skin layer (C-1) was filled into a printing device equipped with a Kyocera inkjet head KJ4B-YH. After that, the gap between the inkjet head and the dried coating film of the adhesive layer paint was set to 3 mm, and the nozzle surface of the inkjet head was wiped. Then, at a driving frequency of 10 kHz, (1) a 100% solid image was printed, then (2) dried at 100°C for 1 minute, and then (3) heated at 150°C for 3 minutes. Synthetic leather 1 was produced by repeating (1) to (3) until the film thickness after drying was about 30 μm.

[0168] (Example 2: Preparation of synthetic leather 2) Synthetic leather 2 was produced through the same steps as in Example 1, except that the black skin layer forming liquid (C-1) was changed to a white skin layer forming liquid (C-2).

[0169] (Comparative Example 1: Preparation of Synthetic Leather 3) The black paint for forming the skin layer (C-3) was applied to a release paper ("EK-100D" manufactured by Lintec Corporation) using a knife coater to a thickness of 150 μm, and then dried using a hot air dryer (70°C x 2 minutes -> 120°C x 2 minutes). The paint for the water-based adhesive layer was applied to the dried coating film using a knife coater to a thickness of 150 μm, and then dried using a hot air dryer (90-100°C x 3 minutes). After that, the coated surface of the dried coating film was bonded to a nonwoven fabric using a hot roll press set at 100-130°C to produce synthetic leather 3. The thickness of the skin layer after drying was about 30 μm.

[0170] (Comparative Example 2: Preparation of Synthetic Leather 4) Synthetic leather 4 was produced by the same process as in Comparative Example 1, except that the black paint for forming the surface skin layer (C-3) was changed to a white paint for forming the surface skin layer (C-4).

[0171] [How to evaluate texture] The synthetic leathers obtained in the Examples and Comparative Examples were evaluated based on the feel when touched with the hand as follows. "A": Excellent volume and softness. "B": Gives a feeling of volume and softness. "C": Slightly inferior in volume and softness. "D": No sense of volume or softness at all.

[0172] [Method for measuring peel strength] A 2.5 cm wide hot melt tape ("BW-2" manufactured by Sun Chemical Industry Co., Ltd.) was placed on the synthetic leather obtained in the examples and comparative examples, and heated at 150°C for 3 minutes to adhere. A sample was cut along the width of the hot melt tape. A part of this sample was peeled off, and the substrate and hot melt tape were clamped with a chuck, and the peel strength was measured using an autograph ("AG-1" manufactured by Shimadzu Corporation) and converted to a 1 cm width. A peel strength of 1 kgf / cm or more was determined to be excellent. "T": Excellent peel strength. "F": Peel strength is insufficient.

[0173] [Inkjet ejection reliability evaluation] The inkjet inks obtained in Production Examples 6 and 7 were filled into an inkjet head KJ4B-YH manufactured by Kyocera Corporation, and the supply pressure was adjusted by setting the head head head water head difference from the head nozzle plate surface to +35 cm and the negative pressure to -5.0 kPa. The head driving conditions were the standard voltage and standard temperature of the inkjet head, the droplet size was set to 18 pL, and a lattice-shaped nozzle check pattern was printed at 20 kHz. After leaving it for 30 minutes, the nozzle check pattern was printed again, and the state of the printed matter was confirmed to determine the inkjet discharge reliability. "T": The check pattern is printed without any gaps. "F": There is a gap in the check pattern or it has not been printed.

[0174] Table 1 summarizes the evaluation results of the examples and comparative examples.

[0175] [Table 1]

[0176] The synthetic leathers of Examples 1 and 2, which are synthetic leathers produced by the synthetic leather production method of the present invention, were obtained without using release paper, which eliminated the waste of release paper. In addition, there were no problems with the texture and peel strength of the synthetic leather. It has been found that the method for producing synthetic leather of the present invention can reduce the amount of waste and greatly contribute to environmental friendliness. [Explanation of symbols]

[0177] 11 Inkjet head for primer 12 Primer liquid 13 Primer dryer 21 Inkjet head for intermediate layer 22 Intermediate layer forming liquid 23 Dryer for middle layer 24 Interlayer thickness gauge 31 Inkjet head for epidermal layer 32 Epidermal layer forming liquid 33 Dryer for epidermal layer 34 Film thickness meter for skin layer 50 Guide roll or transport roll 70 Base material roll 80 Product winding roll 100 Fibrous base material 110 Primer layer 120 Middle Class 130 Epidermal layer 150 Synthetic leather 200 Vehicle seats 201 Synthetic leather for vehicle seating 202 Synthetic leather for vehicle seat backs 203 Synthetic leather used in vehicle headrests 211 Base material for cushioning material for vehicle seating area 212 Base material for cushioning material for vehicle seat backrest 221 Skin layer laminated on cushion material for vehicle seating area 222 Skin layer laminated on cushion material for vehicle seat backrest 300 Inkjet head moving arm (only a part of it is shown)

Claims

1. A method for producing synthetic leather and / or artificial leather comprising a fibrous base material and a skin layer, comprising: The fibrous substrate is selected from the group consisting of nonwoven fabrics, knitted fabrics, and woven fabrics; A method for producing synthetic leather and / or artificial leather, comprising the step of forming the surface layer on the fibrous base material by an inkjet method.

2. 2. The method for producing the synthetic leather and / or artificial leather according to claim 1, comprising a step of applying an aqueous urethane resin dispersion containing at least a urethane resin composition and water by an inkjet method, and then drying the applied aqueous urethane resin dispersion to form the surface layer.

3. 3. The method for producing a synthetic leather and / or an artificial leather according to claim 2, wherein the urethane resin composition has an anionic group and / or a nonionic group.

4. The method for producing a synthetic leather and / or an artificial leather according to claim 2 , wherein the urethane resin aqueous dispersion further contains a pigment.

5. 5. The method for producing a synthetic leather and / or an artificial leather according to claim 4, wherein the pigment is carbon black or titanium oxide.

6. A method for producing synthetic leather and / or artificial leather as described in claim 1 or 2, wherein the thickness of the epidermis layer is 0.5 to 100 μm.

7. The synthetic leather and / or artificial leather further comprises an intermediate layer, 3. A method for producing a synthetic leather and / or an artificial leather according to claim 1 or 2, comprising a step of forming the intermediate layer on the fibrous base material by an inkjet method to obtain a fibrous base material having an intermediate layer.

8. 3. The method for producing a synthetic leather and / or an artificial leather according to claim 1, further comprising a step of forming a surface treatment layer on the surface of the skin layer using a surface treatment agent.

9. An apparatus for producing synthetic leather and / or artificial leather comprising a fibrous base material and a skin layer, comprising: The fibrous substrate is selected from the group consisting of nonwoven fabrics, knitted fabrics, and woven fabrics; The fibrous base material conveying means and / or the inkjet head moving means, the inkjet head, and the dryer are provided, The manufacturing apparatus obtains synthetic leather and / or artificial leather by forming a surface layer on the fibrous base material by an inkjet method.

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