JP2006523756A - Aqueous polyurethane composition and synthetic leather having novel structure - Google Patents

Abstract

The present invention is a water-based polyurethane composition useful for the preparation of synthetic leather, wherein the water-based polyurethane chain extension product is contained in an average particle diameter of 0.1 to 30% by weight based on the total weight of the composition An aqueous polyurethane composition comprising 0.5 to 50 μm fine particles and having a viscosity of 500 to 100,000 cps; and an adhesive layer added between the porous layer and the substrate layer, It is an object of the present invention to provide a water-based polyurethane synthetic leather having a novel structure with increased adhesion. As a result, the obtained synthetic leather can exhibit good properties (high adhesive strength, high chemical resistance, etc.) and excellent cushioning properties, and is particularly useful as a shoe material.

Description

  The present invention relates to an aqueous polyurethane composition and an aqueous polyurethane synthetic leather having a novel structure. More specifically, (a) an aqueous polyurethane composition useful for the preparation of synthetic leather, which is contained in the aqueous polyurethane chain extension product in an amount of 0.1 to 30% by weight based on the total weight of the composition. An aqueous polyurethane composition comprising fine particles having an average particle size of 0.5 to 50 μm and a viscosity of 500 to 100,000 cps; and (b) an adhesive layer is added between the porous layer and the base layer ( On the other hand, in conventional synthetic leather, an adhesive layer is added between the porous layer and the skin layer), and an aqueous polyurethane synthesis having a novel structure with increased adhesion between the porous layer and the base layer For leather. As a result, the synthetic leather can exhibit good characteristics (high adhesive strength, high chemical resistance, etc.) and excellent cushioning properties.

  Due to its various properties, polyurethane resins have been applied to various fields including synthetic leather and paint. A conventional method for producing synthetic leather using a polyurethane resin is, for example, adding an organic solvent such as dimethylformamide (DMF) to a material for preparing a porous layer, and applying the resulting mixture to a base fiber. This is a solvent system in which this is immersed in water and cured while replacing the organic solvent with water, and then the water is removed to produce a porous layer. This is sometimes called a wet method because of the process of immersing in water. The most serious problem in this organic solvent-based method is the use of organic solvents that cause air pollution. In recent years, new rules have been introduced to limit the substances and methods that cause contamination. For this reason, in order to solve these problems, many attempts have been made to prepare synthetic leather using an aqueous polyurethane resin.

  A feature of the water-based polyurethane method is that essentially no organic solvent is used. In other words, in the preparation of the polyurethane prepolymer, a hydrophilic component is added or incorporated to produce a hydrophilic prepolymer, the prepolymer is dispersed in water, and a polymerization reaction is performed using a chain extender. As a result, the water-based polyurethane method does not use an organic solvent such as DMF, and therefore does not cause environmental pollution.

  This advantage of the water-based polyurethane method has been successfully applied in the field of paint, but not in the field of synthetic leather. In order for synthetic leather to replace natural leather, it must have a so-called cushioning (cushion-like) property, i.e., a soft and elastic characteristic. None of the water-based polyurethane synthetic leathers met this requirement. This is because in the conventional synthetic leather manufacturing method using water-based polyurethane, bubbles disappear and the structure becomes dense, and cushioning properties cannot be obtained. Efforts have been made to solve this problem, but no essential results have been achieved. For example, an alternative method has been developed by adding a thermally decomposable inorganic substance to an aqueous polyurethane resin and heating it to generate gas, resulting in a porous structure. The quality structure is weak and the method is complicated. On the other hand, many related companies have facilities for producing solvent-based polyurethane synthetic leather. If these facilities can be used in a new method as they are, it is extremely desirable from the viewpoint of manufacturing cost.

  In FIG. 1, the structure in the synthetic leather 100 of a prior art is shown. This is a base layer 200 made of cloth or a cloth impregnated with a resin, a porous layer 300 that provides cushioning properties, and an adhesive layer 400 that is positioned on the porous layer 300. And a skin layer 500 located on the adhesive layer 400. However, the construction of this synthetic leather cannot meet the requirements in various applications.

  Shoes, which are the main use of polyurethane synthetic leather, are required to have superior characteristics as compared with clothes, interior decoration materials and vehicle interior materials. In other words, the shoe should be capable of maintaining its essential characteristics against harsh external influences. For example, synthetic leather useful for shoes is required to have adhesive strength, chemical resistance, cushioning properties and the like that can be maintained even under high temperature and high humidity conditions. However, the synthetic leather having the configuration of FIG. 1 cannot satisfy these requirements.

  One object of the present invention is to provide an aqueous polyurethane composition used for preparing a synthetic leather having excellent properties corresponding to natural leather without using a solvent causing environmental pollution.

  Another object of the present invention is to provide a water-based polyurethane synthetic leather having a novel structure capable of maintaining high adhesive strength and chemical resistance even under high temperature and high humidity conditions and exhibiting good cushioning properties. .

  The present inventors have diligently studied and conducted many experiments, and then added a fine particle of a specific size to a polyurethane chain extension product synthesized by an aqueous polymerization reaction, thereby having an aqueous polyurethane composition having a specific range of viscosity. It was also found that the synthetic leather produced with the water-based polyurethane composition, particularly the porous layer of synthetic leather, has properties very similar to those of the solvent-based polyurethane synthetic leather, in particular, cushioning properties. The present inventors further obtain a water-based polyurethane adhesive layer even when an aqueous polyurethane adhesive layer is added between the base layer and the porous layer (without adding an additional adhesive layer between the skin layer and the porous layer). It has been found that synthetic leather can exhibit high adhesive strength and chemical resistance and good cushioning properties even at high temperatures and high humidity. The present invention has been completed based on these findings.

According to the present invention, an aqueous polyurethane composition comprising:
(I) a water-based polyurethane chain extension product; and (ii) fine particles having an average particle size of 0.5 to 50 μm, contained in an amount of 0.1 to 30% by weight based on the total weight of the composition. An aqueous polyurethane composition is provided that is between 500 and 100,000 cps.

  This water-based polyurethane composition is particularly useful for preparing a porous layer of synthetic leather, and the synthetic leather thus prepared is comparable to that of synthetic leather produced using a solvent-based polyurethane resin. Shows good cushioning properties.

  The term “aqueous polyurethane chain extension product” used in the present disclosure refers to a product synthesized by an aqueous method that contains a hydrophilic ionic group in the polyurethane polymer structure and can be stably dispersed in water. Means. Therefore, the aqueous polyurethane chain extension product is different from the solvent-based polyurethane chain extension product, and it is not necessary to use an organic solvent such as DMF in the preparation procedure. As long as it has the above characteristics, the type of the aqueous polyurethane chain extension product is not particularly limited.

Examples of aqueous polyurethane chain extension products include:
(A) an isocyanate compound having at least two isocyanate groups;
(B) an organic compound having at least two isocyanate-reactive groups; and (c) reacting one or two isocyanate-reactive groups with an organic compound having at least one hydrophilic ionic group;
(D) A polyurethane prepolymer having isocyanate groups at both ends, 0.1 to 10 moles of the hydrophilic ionic group per molecule, and a number average molecular weight of 1,000 to 30,000 was synthesized. Then, the prepolymer (d) may be neutralized, dispersed in water, and subjected to chain extension to obtain the aqueous polyurethane chain extension product. Unless otherwise described below, the above parameters (amount of each group, molecular weight, etc.) represent optimum conditions for completion of the present invention.

  When the polyurethane prepolymer is neutralized and dispersed in water, a self-emulsified dispersion in which hydrophilic ionic groups are exposed on the surface is formed and exhibits good dispersibility in water. When a chain extender (chain extender) is added to the dispersion thus prepared, the functional group of the chain extender reacts with the unreacted residual isocyanate group of the prepolymer to produce an aqueous polyurethane chain extension product. To do.

  A desired polyurethane composition can be obtained by uniformly dispersing fine particles made of an organic and / or inorganic material added to the water-based polyurethane chain extension product into the chain extension product by stirring. During such a dispersion procedure, air by particulates (those introduced into the composition and / or contained in the particulates (including those present inside and / or on the surface of the particulates)) Are retained in the composition, and as a result, the resulting synthetic leather (especially its porous layer) can exhibit cushioning properties. The microparticles also serve as fillers useful for maintaining the structure of the porous layer.

  As defined above, the average particle size of the fine particles is preferably 0.5 to 50 μm. If the average particle size is too small, it is difficult to uniformly disperse the fine particles, and the ability to form air pockets is reduced. On the other hand, if the average particle size is too large, fine particles tend to collect on the upper or lower portion of the synthetic leather due to its specific gravity, or tend to harden the synthetic leather. However, when the added fine particles are present in an aggregated state, a particle diameter exceeding the above upper limit can be allowed in order to show the intended effect of the present invention.

  As defined above, the amount of fine particles added is preferably 0.1 to 30% by weight, based on the total weight of the composition. If the amount added is too small, it becomes difficult to have the ability to form bubbles and retain the structure (for example, the porous layer). On the other hand, if the addition amount is too large, viscosity is increased, the moldability of the synthetic leather is lowered, and the synthetic leather becomes hard, which is not preferable. More preferably, the addition amount is 1 to 10% by weight.

  The viscosity of the aqueous polyurethane composition of the present invention is important from the viewpoint of bubble formation, laminated structure forming ability and structure supporting ability, and is used for the molecular weight of the aqueous polyurethane chain extension product, the average particle size and the added amount of fine particles, and dispersion. It depends on various factors such as the amount of water. As defined above, such a viscosity is preferably 500 to 100,000 cps, and if the viscosity is too low, the bubble-forming ability and the structural support ability decrease, whereas if the viscosity is too high, the laminated structure The ability to form decreases. More preferably, the viscosity is 5,000 to 30,000 cps.

  In one embodiment, a thickener, a crosslinking agent (curing agent), an antifoaming agent, a pigment, a dispersing agent, a molding agent, a surfactant, a leveling agent (smoothness) are used as long as the effects of the present invention are not adversely affected. Agents), wetting agents, antifouling agents (water and oil repellents), and the like. The amount of these components added is generally 0.05 to 10% by weight based on the total weight of the composition.

  The aqueous polyurethane composition of the present invention is preferably useful for forming a porous layer of synthetic leather.

  An exemplary method for preparing a porous layer is shown below.

  In the preparation method, 0.05 to 10% by weight of fine particles having an average particle size of 0.5 to 50 μm are added to an aqueous polyurethane chain extension product based on the total weight of the composition and stirred to obtain a large number of fine bubbles. And a step of producing a water-based polyurethane composition having a viscosity of 500 to 100,000 cps; and applying the composition to a substrate layer at a thickness of 0.1 to 3 mm to form a porous layer. Become. In one embodiment, a skin layer may be further formed on the porous layer. In other embodiments, an adhesive layer is further added between the skin layer and the porous layer, between the porous layer and the substrate layer, or between the skin layer and the porous layer and simultaneously between the porous layer and the substrate layer. However, a stronger bond may be ensured.

Particularly preferred constitution of the water-based polyurethane synthetic leather is
(I) a substrate layer made of the fabric itself or a fabric impregnated with a resin and forming a synthetic leather substrate;
(Ii) an adhesive layer located on the base layer and contributing to strengthening the bond between the porous layer and the base layer;
(Iii) a porous layer located on the adhesive layer and providing cushioning properties of natural leather; and (iv) a skin layer located on the porous layer and forming the surface of the synthetic leather. It becomes.

  This configuration of the water-based polyurethane synthetic leather is characterized in that an adhesive layer is added between the base layer and the porous layer, and the resulting synthetic leather is extremely useful as a shoe material. The adhesive layer reinforces the adhesion between the base layer and the porous layer, and provides high adhesive strength required for leather materials for shoes, especially in high temperature and high humidity conditions. To provide the necessary synthetic leather properties. The adhesive layer is not particularly limited as long as the above conditions are satisfied, and can be manufactured using a material used in the technical field related to the present invention.

  For example, the skin layer may be made of a polyurethane resin obtained by adding a curing agent to the aqueous polyurethane chain elongation product and subjecting it to a crosslinking reaction.

  Since the porous layer contains a large number of fine bubbles, it serves to provide good cushioning properties. Preferably, the porous layer is manufactured from the above water-based polyurethane composition containing fine bubbles, but is not limited thereto. .

  As the fabric used for the base layer, synthetic or natural woven fabric, non-woven fabric, knitted fabric, ultrafine fiber fabric, high-density fabric and the like known to those skilled in the art can be used. Further, the substrate layer may be either the cloth itself or a form of cloth impregnated with resin. The cloth impregnated with the resin is, for example, a cloth obtained by impregnating the cloth with a polyurethane resin, and the types of resins and methods used for impregnation can be those known to those skilled in the art. Such a detailed description itself is omitted in this specification.

The method for producing a water-based polyurethane synthetic leather having the above-described configuration includes, for example, the following steps:
(A) A step of applying a water-based polyurethane resin to the release thin film at a thickness of 0.05 to 1 mm to form a skin layer and then drying;
(B) A step of applying a water-based polyurethane resin containing fine bubbles to the skin layer in a thickness of 0.1 to 3 mm to form a porous layer and then drying;
(C) a step of applying an adhesive resin to the porous layer at a thickness of 0.01 to 1 mm to form an adhesive layer; and (D) impregnating the adhesive layer with a cloth itself or a resin. A step of bonding a cloth to form a base layer and then removing the release film.

  The release film that is temporarily applied to the skin layer is preferably embossed so as to give an appearance similar to the surface of natural leather.

  The step of applying to the skin layer and the porous layer is performed by repeating the coating / drying procedure one or more times, so that the final layer thickness is within the range specified above. It becomes. The drying procedure in steps (A) and (B) can be performed at 70 to 150 ° C. for 1 to 60 minutes. Longer drying times are required at lower drying temperatures above the above, reducing process efficiency, while higher drying temperatures above the above, for example, crack the layer or cause the layer to warp. This is undesirable because it degrades the leather.

  In the step (D), after applying the cloth or the cloth impregnated with the resin, pressure may be applied thereto. Thereby, stronger adhesion between the adhesive layer and the base material layer is completed, and at the same time, the surface of the skin layer can be formed to correspond to the embossed surface of the release thin film.

  Further, in the step (D), an aging step is further included after the formation of the base material layer and before the peeling of the peeled thin film. The aging can be performed at about 50 to 100 ° C. for about 1 to 24 hours, but is not limited to these temperatures and times.

  The present invention is described in more detail below. Initially, the materials exemplified above will be described in detail with respect to the water-based polyurethane composition, although some of the same materials are also used in the manufacture of the skin and adhesive layers.

  The isocyanate compound (a) is a compound having at least two isocyanate groups (—NCO) per molecule, and preferably a compound having two isocyanate groups per molecule. This isocyanate compound is, for example, tetramethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 1-isocyanate-isocyanate methyl-3. , 5,5-trimethylcyclohexane, bis- (4-isocyanatomethyl) cyclohexane, bis- (4-isocyanate-3-methyl-cyclohexyl) -methane, and the like can be used.

As used herein, an “isocyanate-reactive group” is a group capable of reacting with an isocyanate group (—NCO) of an isocyanate compound and is a group having one or more reactive hydrogens, such as a hydroxyl group ( -OH), thio (-SH) and a primary or secondary amine _(-NH 2, = indicates the N-H) or the like.

  Organic compounds having at least two isocyanate-reactive groups per molecule include, for example, dicarboxylic acids such as succinic acid, adipic acid, suberic acid, azelaic acid, phthalic acid, isophthalic acid and terephthalic acid, ethylene glycol, propylene glycol Dihydroxypolyester obtained by reacting diol compounds such as diethylene glycol, butanediol, hexanediol, neopentine glycol, 2-methylpropanediol; dihydroxypolyacetone such as ε-caprolactone; diallyl carbonate and diol compound Those obtained by those skilled in the art such as dihydroxy polycarbonates obtained; various dihydroxy polyethers; dithiopolythioethers; dihydroxy polyacetals can be used.

  Since the organic compound (c) has a hydrophilic ionic group in the side chain of the molecule, it gives the polyurethane prepolymer a water dispersibility, and since it has an isocyanate reactive group, at one or both ends thereof. It can react with an isocyanate compound (a). Therefore, the organic compound (c) constitutes an element as the main chain of the polyurethane prepolymer by the reaction with the isocyanate compound (a), and is also dispersed when the synthesized prepolymer is dispersed in water. Located on the surface of the agent, imparts dispersibility to the prepolymer.

The hydrophilic ionic group may be either an anionic or cationic group when neutralized, and includes, for example, —CO ₂ —, —SO ₃ —, = N ⁺ =, = S ⁺ -, and the like. . Of these, the carboxoxyl anion group (—CO ₂ —) is particularly preferable. The organic compound (c) having a carboxyl group as an ionic group includes, for example, a dihydroxycarboxylic acid compound having a hydroxyl group at both ends and also having at least one carboxyl group. Typical examples include citric acid, tartaric acid, dimethylpropionic acid (DMPA), dimethylbutanoic acid (DMBA), and the like.

In one embodiment, depending on the polymerization reaction, in addition to the organic compound (c), in addition to the organic compound (c), the main chain or side chain may be further added to form a water-based polyurethane prepolymer having better water dispersibility. Another organic compound (c ′) having a hydrophilic nonionic group and an isocyanate-reactive group at both ends thereof may be added in a proportion of 1 to 50% by weight based on the total weight of the prepolymer. Furthermore, the prepolymer containing the organic compound (c ′) can maintain a stable dispersibility in water even if the pH value varies. As the hydrophilic nonionic groups, for example, hydrophilic ethylene oxide units _(-CH 2 O-) is.

  The amount of the isocyanate compound (a) and the organic compound (b) is determined by the molecular weight of the polyurethane prepolymer to be synthesized regardless of whether the isocyanate group is present at one or both ends. This amount is also determined by the amount of hydrophilic ionic groups contained in one molecule of the synthesized polyurethane prepolymer. Therefore, the amount of these components need not be particularly limited. This is because the molecular weight of the polyurethane prepolymer and the amount of hydrophilic ionic groups contained in one molecule of the synthesized prepolymer are the same regardless of whether the isocyanate group is present at one or both ends. This is because it can naturally be determined within the range.

  The process for producing a polyurethane prepolymer by the reaction of an isocyanate group-containing compound and an isocyanate-reactive group-containing compound is already a method known to those skilled in the art, and therefore a detailed description is omitted here.

  The polyurethane prepolymer thus produced is neutralized, dispersed in water and chain extended to produce an aqueous polyurethane chain extension product.

  In general, hydrophilic ionic groups are present as strong ionic groups in the organic compound (c), where the strong ionic groups exhibit only a low solubility in water. If this strong group reacts with the neutralizing agent before or after the polymerization reaction, it is converted to an anionic or cationic group with high solubility, as indicated above. The type of neutralizing agent is determined by the nature of the ionic group; for example, when the ionic group is an anion, a basic compound is used as the neutralizing agent, and when the ionic group is a cation, an acidic compound is used. used. Examples of basic neutralizing agents include soluble tertiary amines and alkali metal hydroxides. Examples of acidic neutralizing agents include organic and inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and benzyl chloride. , Epichlorohydrin, glycolic acid, dimethyl sulfate, hydrobromic acid, trichloroacetic acid, trifluoroacetic acid, sulfonic acid and acetic acid. The neutralizing agent is preferably used in an amount that neutralizes all hydrophilic ionic groups, but in any case it may be only 50% of the above amount.

  The amount of water used for dispersion is not particularly limited, but can be appropriately determined in consideration of other factors.

When the polyurethane prepolymer (d) is neutralized and dispersed in water, between the isocyanate groups present at the ends of the polymer, the isocyanate groups in contact with water convert carbon dioxide (CO ₂ ). It reacts with water as it evolves and changes to an amine group (—NH ₂ ). The remaining isocyanate groups continue to exist in an active state. These active isocyanate groups react with the chain extender (e) added to the dispersion of polyurethane prepolymer (d) to give a polymerized polyurethane chain extension product (f).

  Thus, the chain extender (e) must have at least two isocyanate reactive groups per molecule. This chain extender (e) includes, for example, diamine compounds such as ethylenediamine, hexamethylenediamine, and isophoronediamine; diol compounds such as ethylene glycol, diethylene glycol, and 1,4 butanediol; triol compounds such as glycerin; melamine, diethylenetriamine, and the like Triamine; triethylenetetraamine, N-methyl-diethanolamine, N-butyl-diethanolamine, N-oleyldiethanolamine, N-cyclohexyl-diethanolamine, N, N-dimethylhydrazine, N, N-dimethylethylenediamine, N, N-dimethyl- Such as propylene diamine.

  In the chain extension reaction, the prepolymer (d) is added to a reactor containing water, and then the chain extender (e) is added thereto, or the chain extender (e) is added to water. By adding the prepolymer (d) to the reactor. The former method is more preferable from the viewpoint of adjusting the molecular weight of the aqueous polyurethane chain extension product (f), high reactivity, and the like.

  One of the characteristics of the present invention is that a composition produced by adding fine particles having specific properties to the aqueous polyurethane chain extension product (f) synthesized above is useful for the production of synthetic leather, This synthetic leather can provide superior properties comparable to solvent-based synthetic leather.

The fine particles capable of producing a water-based polyurethane synthetic leather having excellent properties are organic and / or inorganic materials, and preferably inorganic materials such as silica. The microparticles can take the form of powder, beads, plates or fibers, and other certain forms. Beaded particles are, for example, commercially available Zeosufea (Zeospheres ^TM, ceramic hollow microspheres), Scotchlite ^TM Glass Bubbles ^{(Scotchlite TM Glass bubbles, 3M Chemicals} ) , and the like.

The porous structure is porous because it can hold a relatively large amount of gas (depending on the reaction conditions, inert gas, air, etc.) in the production of synthetic leather, which can further enhance cushioning properties. Fine particles having a structure are more preferable. The kind of porous structure is not particularly limited. In other words, the fine particles themselves may have either a porous surface structure or a porous internal structure, and in any case, many fine particles may aggregate to form a porous aggregate structure. Examples of commercially available fine particles having a porous surface structure include Matsumoto Microsphere ^TM (Matsumoto Yushi Seiyaku Co., Ltd.) and K1 (3M Chemicals) which are hollow polymer microspheres having a particle diameter of 20 to 100 μm. Is mentioned. Specifically, the microparticles are thermo-expandable microspheres or microporous aggregates. Commercially available heat-expandable microspheres, for example, a particle size 10 to 30 [mu] m, respectively, can be expanded to more than twice their size during overheating, Expancel ^TM ( EXPANCEL ^TM, Akzo Nobel), Matsumoto microsphere ^TM F Series (Matsumoto Yushi-Seiyaku Co., Ltd.), and the like. In accordance with the present invention, if the composition contains heated microspheres, some of them take an expanded form and others take a broken form, but they are manufactured synthetically Helps leather to provide cushioning. Examples of commercially available microporous aggregates include Nigel ^™ , Nipsyl ^™ (NIGEL ^™ , NIPSIL ^™ , Nippon Silica Industrial Co., Ltd.) and the like. In accordance with the present invention, when the composition includes microporous aggregates, some of the polyurethane resin of the composition penetrates some pores of the aggregate and enhances the bond between the aggregate and the composition. On the other hand, the remaining holes into which the resin has not penetrated can give good cushioning properties.

  The fabric used for the base layer of the synthetic leather includes various woven fabrics, non-woven fabrics, knitted fabrics, ultrafine fiber fabrics, high-density fabrics, etc., but those known to those skilled in the art of synthetic leather and the fabric itself, or It may be a cloth impregnated with resin. The cloth impregnated with the resin can be produced, for example, by impregnating the polyurethane resin into the cloth in the synthetic leather production process. The aqueous polyurethane composition is applied onto the fabric to form a porous layer. As the resin used for the resin-impregnated cloth, a polyurethane resin used for synthetic leather, which is known to those skilled in the art, can be employed. It is preferably an aqueous polyurethane composition according to the invention which does not contain fine particles, ie an aqueous polyurethane chain extension product (f). Preferably, as already mentioned, an adhesive layer is added between the substrate layer and the porous layer in order to improve the adhesive strength between these layers. As long as the adhesive strength between these layers can be improved, the adhesive used for the adhesive layer is not particularly limited.

  In the synthetic leather thus produced, a skin layer may be further formed by surface coating, if necessary; surface coating methods and materials therefor are well known to those skilled in the art, so that detailed descriptions are provided. The description is omitted in this specification.

  If necessary, the method for producing a synthetic leather of the present invention can include further steps as long as the effects of the present invention are not impaired, but should be regarded as being included in the scope of the present invention. is there. For example, in order to easily control the viscosity of the prepolymer (d), a trace amount of an organic solvent such as acetone may be added. Further, an emulsifier may be further added for good dispersion of the prepolymer (d). Furthermore, a thickener is used to improve the viscosity of the composition, a crosslinking agent (or curing agent) is used to improve the strength, and an antifoaming agent is used to adjust the formation of cells (pores). In addition, a pigment may be further added. In addition, a foaming agent, a surface active agent, a smoothing agent, a wetting agent, a water-and-oil repellent, and the like may be added. Examples of the thickener include polyurethane compounds, polyacrylate compounds, cellulose derivatives, and the like. Examples of the crosslinking agent include polyisocyanate compounds, methylol melamine compounds, aziridine compounds, and oxazoline compounds. Examples of the antifoaming agent include silicon compounds, alcohol compounds, and fatty acid compounds. Examples of the pigment include titanium dioxide and carbon black. However, these are only typical ones, and other known ones can be added.

  The invention will be explained in more detail by the following preparation examples and examples. However, it will be understood that the invention is not limited to these specific preparations and examples, but includes various modifications that would be recognized by one skilled in the art to which the invention relates.

Production Example 1: Production of polyurethane polymer 120.8 g of isophorone diisocyanate as the isocyanate compound (a), 469 g of polytetramethyl glycol as the organic compound (b), and 42.2 g of dimethylpropionic acid as the organic compound (c), Reaction was performed at 80 ° C. for 3 hours to produce 632 g of a polyurethane prepolymer.

Production Example 2: Production of aqueous polyurethane composition Triethylamine was added to the polyurethane prepolymer produced in Production Example 1 as a basic neutralizing agent. 632 g of the polyurethane prepolymer thus neutralized was added to a reaction vessel containing 1,000 L of water and stirred at 500 rpm to form a dispersion. Thereafter, 13 g of ethylenediamine was added thereto as a chain extender and subjected to an extension reaction for 2 hours to produce a polyurethane chain extension composition. To the reaction solution, fine particles, thickener, antifoaming agent, pigment, curing agent and the like are added as described in Table 1 below, and stirred at 500 rpm for 30 to 60 minutes to obtain an aqueous polyurethane composition (slurry ) Was manufactured. The produced polyurethane composition was measured to have a viscosity of about 5,000 to 30,000 cps, depending on the amount of thickener added.

Examples 1 to 5: Manufacture of synthetic leather In order to form a base layer of synthetic leather, the aqueous polyurethane composition produced in Production Example 2 was applied to a nonwoven fabric with a thickness of 1 mm and dried at 100 ° C for 5 minutes. Thereafter, it was dried again at 130 ° C. for 30 minutes to produce a synthetic leather semi-finished product in which a porous layer was directly formed on the base layer.

  1 g thickener (TAFIGEL PUR-40; Munging Chemie Corp.) and 10 g pigment dispersant (WHITE 100; KF Tech Corp.) are added to an aqueous polyurethane resin (Genud-SLT-220; Gentrol). Stir well. Next, the obtained mixture was applied to an A4 size peeling thin film with a thickness of 0.1 mm and dried at 130 ° C. for 2 minutes. Subsequently, the same mixture was applied again so that the total thickness became 0.15 mm, and dried at 130 ° C. for 2 minutes to form a skin layer on the peeled thin film. On the skin layer, an aqueous polyurethane resin (Genud-SLT-220; Gentrol) was applied as an adhesive so that the total thickness was 0.3 mm, and an adhesive layer was formed. Shortly thereafter, the intermediate product was affixed so that the porous layer of the intermediate product composed of the base layer and the porous layer produced above faced the adhesive layer.

[Characteristic test 1]
-Cushion property test: The flexibility and restorability when the specimen was pushed by hand was evaluated. The highest quality was set to 100%, and relative values were evaluated based on this highest quality. If the value is less than 30%, the material does not exhibit cushioning properties as synthetic leather.
-Wear test: The test piece was subjected to a wear test in accordance with ASTM D3884. The amount of wear was expressed in mg.
-Room temperature bending test ("Bally Flex Test"): The test specimen was subjected to a bending tester and subjected to repeated bending tests at 25 ° C. The number of bends until the specimen was cracked was counted.
-Hydrolysis resistance test: The specimen was immersed in a 10% NaOH aqueous solution, and after a certain period of time, the surface crack was measured.

  As can be seen from the above table, all of the synthetic leathers of Examples 1 to 5 produced according to the present invention showed excellent values for cushioning and other properties required for synthetic leather.

Comparative Example 1
A synthetic leather was produced in the same manner as in Examples 1 to 5 except that fine particles were not added, and a characteristic test was performed. Although general properties such as abrasion resistance and light resistance are not bad, it was evaluated that the cushioning property was 20% which did not reach the level required for synthetic leather.

Example 6: Production of synthetic leather 1 g of thickener (TAFIGEL PUR-40; Munging Chemie Corp.) and 10 g of pigment dispersant (WHITE 100; K.F. Tech Corp.) were added to an aqueous polyurethane resin (Genud- SLT-220; Gentrol) and well stirred. Next, as shown in FIG. 3, the obtained mixture was applied to an A4 size peeling thin film 600 with a thickness of 0.1 mm and dried at 130 ° C. for 2 minutes. Subsequently, the same mixture was applied again so that the total thickness became 0.15 mm, and dried at 130 ° C. for 2 minutes to form the skin layer 500 on the peeling thin film 600. The aqueous polyurethane composition produced in Production Example 2 was applied on the skin layer 500 so that the total thickness was 0.3 mm, and dried at 100 ° C. for 5 minutes. Then, the same composition was apply | coated so that the total thickness might be set to 0.6 mm, and it dried at 100 degreeC for 5 minute (s), and the porous layer 300 was formed. On the porous layer 300, the same resin as that used for the skin layer was applied so that the total thickness became 0.8 mm, and the adhesive layer 400 was formed. Shortly thereafter, a nonwoven fabric was applied to the adhesive layer 400 to form a base layer 200, which was dried at 100 ° C. for 5 minutes to produce a layered composite structure, and then aged at 80 ° C. for 12 hours. The release thin film was removed to produce an aqueous polyurethane synthetic leather 100.

  About this synthetic leather, the characteristic test as described in Examples 1-5 was done, and the following peeling tests were also done. The results are shown in Table 2 below.

[Characteristic test 2]
-Peel test: The rubber is adhered to the specimen so that the skin layer of the specimen faces the rubber, and then subjected to a UTM apparatus (LR-5K; Lloyd Co., Ltd.) until the specimen peels. The force applied to was measured.

  A cross-sectional view of the synthetic leather produced above was observed through a scanning electron microscope (SEM). A SEM photograph and a photograph obtained by enlarging this are shown in FIGS. 4 and 5, respectively. Referring to these photographs, it can be confirmed that the porous layer contains many fine particles and cells such as water droplets. The microparticles are used to support the porous layer so that the porous cells can be retained within the porous layer during the production of the porous layer. Shown on the porous layer is a skin layer that does not have particulates and porous cells, which contributes to surface texture, strength, and other general properties of synthetic leather. It is also shown that some of the adhesive layer under the porous layer penetrates the substrate layer. From this configuration, high adhesive strength can be obtained. This is because the porous layer and the adhesive layer are made of the same polyurethane-based resin and have an affinity to ensure good adhesion between the porous layer and the adhesive layer. This is because some of the adhesive penetrates the base layer so that the adhesive layer and the base layer have excellent adhesion. As a result, the water-based polyurethane synthetic leather having this novel configuration can exhibit better adhesive strength even under high-temperature and high-humidity conditions as compared with water-based polyurethane synthetic leather according to the prior art.

Comparative Example 2
The same aqueous polyurethane composition as in Example 6 was applied on the same nonwoven fabric as in Example 6 to a thickness of 0.1 mm and dried at 100 ° C. for 5 minutes. Then, the same aqueous polyurethane composition was applied thereon so that the total thickness was 0.6 mm, dried at 100 ° C. for 5 minutes, and then dried at 130 ° C. for 30 minutes, as shown in FIG. Manufactured synthetic leather semi-finished products. This is because the porous layer 300 is formed directly on the base layer 200. On the other hand, 1 g of a thickener (TAFIGEL PUR-40; Munging Chemie Corp.) and 10 g of a pigment dispersant (WHITE 100; KF Tech Corp.) were added to an aqueous polyurethane resin (Genud-SLT-220; Gentrol). In addition to stirring. Next, the obtained mixture was applied to an A4 size peeling thin film 600 with a thickness of 0.1 mm and dried at 130 ° C. for 2 minutes. Subsequently, the same mixture was applied again so that the total thickness became 0.15 mm, and dried at 130 ° C. for 2 minutes to form the skin layer 500 on the peeling thin film 600. A water-based polyurethane resin (Genud-SLT-220; Gentrol) was applied as an adhesive on the skin layer 500 so that the total thickness was 0.3 mm, and the adhesive layer 400 was formed. Shortly thereafter, the intermediate product was affixed so that the porous layer 300 of the intermediate product composed of the base layer 200 and the porous layer 300 produced above faced the adhesive layer 400. After pressing, the release thin film was removed to produce the synthetic leather of FIG. About the manufactured synthetic leather, the characteristic test was done by the same method as Example 6, and the result was described in Table 2 below.

As shown in Table 2, the synthetic leather produced in Example 6 according to a preferred embodiment of the present invention has excellent cushioning properties and excellent adhesive strength of 3.0 kg / cm ² or more, This satisfies the strength required for synthetic leather for shoes and the minimum adhesive strength is 2.5 kg / cm ² . Furthermore, when a threshold force was applied, the substrate layer (eg, a nonwoven fabric impregnated with resin) separated, indicating that the adhesion between the porous layer and the substrate layer was very good. ing. On the other hand, the synthetic leather produced in Comparative Example 2 showed good cushioning properties by containing the same fine particles as in Example 6, but with a low adhesive strength of 2.0 to 2.5 kg / cm ^2. Yes, when a limit force is applied, the porous layer and the base layer are separated from each other, indicating that the adhesion between them is weak.

  As explained above, the water-based polyurethane composition according to the present invention can be produced without using an organic solvent such as DMF causing environmental pollution. In addition, the synthetic leather produced using this composition has excellent properties almost comparable to those of solvent-based polyurethane synthetic leather, and has particularly excellent cushioning properties. Furthermore, the synthetic leather having a novel structure according to the present invention exhibits high adhesive strength and excellent chemical resistance as well as excellent cushioning properties even under high temperature and high humidity conditions.

  Other embodiments and uses of the invention will be apparent to those skilled in the art from consideration of the specification or examination of the practice of the invention disclosed herein. Together with the scope of the specific embodiments of the claimed invention, the scope of the embodiments of the invention is indicated in the claims, and the specification and examples are intended to be considered merely exemplary. Has been.

FIG. 1 is a schematic view of a cross-sectional structure of a conventional water-based polyurethane synthetic leather. FIG. 2 is a schematic view of a cross-sectional structure of the aqueous polyurethane synthetic leather of the present invention. FIG. 3 shows a method for producing the water-based polyurethane synthetic leather of FIG. FIG. 4 is a scanning electron micrograph of a cross-sectional view of the synthetic leather produced in Example 6. FIG. 5 is an enlarged view of FIG.

Explanation of symbols

100: Water-based polyurethane synthetic leather 200: Base layer 300: Porous layer 400: Adhesive layer 500: Skin layer 600: Peeling thin film

Claims (9)

An aqueous polyurethane composition comprising:
(I) a water-based polyurethane chain extension product; and (ii) fine particles having an average particle size of 0.5 to 50 μm, contained in an amount of 0.1 to 30% by weight based on the total weight of the composition. An aqueous polyurethane composition having a mass of 500 to 100,000 cps. The aqueous polyurethane chain extension product (i) is
(A) an isocyanate compound having at least two isocyanate groups;
(B) an organic compound having at least two isocyanate-reactive groups; and (c) reacting one or two isocyanate-reactive groups with an organic compound having at least one hydrophilic ionic group;
(D) A polyurethane prepolymer having isocyanate groups at both ends, 0.1 to 10 moles of the hydrophilic ionic group per molecule, and a number average molecular weight of 1,000 to 30,000 was synthesized. Then, the prepolymer (d) is neutralized, dispersed in water and subjected to chain extension to obtain the aqueous polyurethane chain extension product (i) as a dispersion. Item 4. The aqueous polyurethane composition according to Item 1.   The water-based polyurethane composition according to claim 1, wherein the fine particles (ii) are made of an organic and / or inorganic material.   The aqueous system according to claim 1, wherein the fine particles (ii) have a porous surface structure, or a plurality of the fine particles (ii) are aggregated to form a porous aggregate structure. Polyurethane composition.   Consists of thickeners, crosslinking agents (curing agents), antifoaming agents, pigments, dispersants, molding agents, surfactants, leveling agents (smoothing agents), wetting agents, antifouling agents (water and oil repellents), etc. The aqueous polyurethane composition according to claim 1, further comprising 0.05 to 10% by weight based on the total weight of the composition, at least one selected from the group.   A method for preparing a porous layer of synthetic leather, comprising using the water-based polyurethane composition according to any one of claims 1 to 5. Water-based polyurethane synthetic leather,
(I) a substrate layer made of the fabric itself or a fabric impregnated with a resin and forming a synthetic leather substrate;
(Ii) an adhesive layer located on the base layer and contributing to strengthening the bond between the porous layer and the base layer;
(Iii) a porous layer located on the adhesive layer and providing cushioning properties of natural leather; and (iv) a skin layer located on the porous layer and forming the surface of the synthetic leather. A water-based polyurethane synthetic leather characterized by having a constitution of: The porous layer is an aqueous polyurethane composition,
(I) a water-based polyurethane chain extension product; and (ii) fine particles having an average particle size of 0.5 to 50 μm, contained in an amount of 0.1 to 30% by weight based on the total weight of the composition. Made of an aqueous polyurethane composition that is 500-100,000 cps,
The aqueous polyurethane chain extension product (i) is
(A) an isocyanate compound having at least two isocyanate groups;
(B) an organic compound having at least two isocyanate-reactive groups; and (c) reacting one or two isocyanate-reactive groups with an organic compound having at least one hydrophilic ionic group;
(D) A polyurethane prepolymer having isocyanate groups at both ends, 0.1 to 10 moles of the hydrophilic ionic group per molecule, and a number average molecular weight of 1,000 to 30,000 was synthesized. Then, the prepolymer (d) is neutralized, dispersed in water and subjected to chain extension to obtain the aqueous polyurethane chain extension product (i) as a dispersion. Item 8. An aqueous polyurethane synthetic leather according to Item 7. A method for preparing an aqueous polyurethane synthetic leather,
(A) A step of applying a water-based polyurethane resin to the release thin film at a thickness of 0.05 to 1 mm to form a skin layer and then drying;
(B) A step of applying a water-based polyurethane resin containing fine bubbles to the skin layer in a thickness of 0.1 to 3 mm to form a porous layer and then drying;
(C) a step of applying an adhesive resin to the porous layer at a thickness of 0.01 to 1 mm to form an adhesive layer; and (D) impregnating the adhesive layer with a cloth itself or a resin. A method for preparing a water-based polyurethane synthetic leather, comprising a step of bonding a cloth to form a base layer and then removing the release film.