JP2014025165A - Method for producing sheet-shaped material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a sheet-shaped material with an environment-friendly production process, which has a uniform raised length equal to that of a sheet-shaped material using organic solvent-based polyurethane, and obtains elegant surface quality superior in fiber denseness and excellent texture superior in softness and repulsive feeling regardless of a type of a foaming agent and polyurethane.SOLUTION: The method for producing the sheet-shaped material comprises applying a polyurethane liquid containing a water dispersion type polyurethane liquid, a foaming agent, an anionic surfactant and/or a zwitterionic surfactant, to a fibrous substrate. The method further can add a foam stabilizer to the polyurethane liquid.

Description

  The present invention relates to an environment-friendly sheet-like material manufacturing method that does not use an organic solvent in the manufacturing process, and particularly relates to a sheet-like material manufacturing method with good surface quality and texture.

  A fibrous base material mainly made of a fabric such as a nonwoven fabric and a sheet-like material made of polyurethane have excellent characteristics not found in natural leather, and are widely used for various uses such as artificial leather. In particular, sheet-like materials using a polyester-based fibrous base material are excellent in light resistance, and therefore their use has been expanded year by year for use in clothing, chair upholstery and automobile interior materials.

  In manufacturing such a sheet-like material, after impregnating the fibrous base material with an organic solvent solution of polyurethane, the obtained fibrous base material is immersed in water or an organic solvent aqueous solution which is a non-solvent of polyurethane. A combination of processes for wet coagulation of polyurethane is generally employed. In this case, a water-miscible organic solvent such as N, N-dimethylformamide is used as the organic solvent that is a solvent for polyurethane. However, since organic solvents are generally highly harmful to the human body and the environment, a technique that does not use organic solvents is strongly demanded in the production of sheet-like materials.

  As a specific solution, for example, a method using a water-dispersed polyurethane liquid in which polyurethane is dispersed in water instead of the conventional organic solvent-based polyurethane has been studied.

  However, a sheet-like material obtained by impregnating a fibrous base material with a water-dispersible polyurethane liquid and coagulating polyurethane has a problem that the texture tends to be hard. One of the main reasons is the difference between the two solidification methods. In other words, the coagulation method of the organic solvent-based polyurethane liquid is a “wet coagulation method” in which polyurethane molecules dissolved in the organic solvent are solidified by solvent substitution with water. When viewed with a polyurethane (PU) film, the density is A low porous film is formed. Therefore, even when PU is impregnated into the fibrous base material and solidified, the adhesion between the fiber and the polyurethane becomes dots, resulting in a soft sheet. On the other hand, the water-dispersed polyurethane is a “wet heat coagulation method” that solidifies by agglomerating PU emulsions by disrupting the hydration state of the polyurethane emulsion dispersed in water mainly by heating. The PU membrane structure is a non-porous membrane with high density. For this reason, the adhesion between the fibrous base material and the PU becomes dense, and the entangled portion of the fiber is strongly gripped, so that the texture becomes hard. In order to improve the texture by applying this water-dispersed polyurethane, that is, to suppress the gripping of fiber entanglement points by polyurethane, a technique for making the structure of polyurethane in a fibrous base material porous is proposed.

  Specifically, a water-dispersed polyurethane liquid containing a foaming agent is applied to a fibrous base material such as a sheet made of a fabric such as a non-woven fabric, and the foaming agent is foamed by heating. It has been proposed that the structure be a porous structure (see Patent Document 1). In this proposal, by making the polyurethane porous, the adhesive area between the fiber and polyurethane is reduced, the gripping force of the fiber entanglement point is weakened, and it is possible to obtain a sheet-like material having a good texture that is soft to the touch. It is. However, in this proposal, when a polyurethane liquid having a high thermal coagulation temperature and a foaming agent having a low foaming start temperature are combined, before the polyurethane liquid coagulates, bubbles generated by foaming are expanded and united. As a result, there is a problem that the porous structure of polyurethane cannot be obtained due to degassing, and the combination of polyurethane and foaming agent is limited.

  Similarly, a method for producing a porous resin by heat-treating a synthetic resin in the presence of a foaming agent has also been proposed (see Patent Document 2). However, as in the previous example, this proposal was also limited in the combination of the synthetic resin and the foaming agent, and was not necessarily a technique for obtaining the intended porous structure.

  As described above, the technology for expressing the porous structure by applying the foaming agent is currently limited by the combination of the thermal coagulation temperature of the polyurethane liquid and the foaming agent start temperature, regardless of the type of polyurethane and foaming agent, No technique for obtaining a porous structure has been proposed.

JP 2011-214210 A JP 2011-116951 A

  Therefore, in view of the background of the above-mentioned conventional technology, the object of the present invention is to provide a uniform feeling equivalent to artificial leather to which organic solvent-based polyurethane is applied, regardless of the type of foaming agent and polyurethane, due to the environment-friendly manufacturing process. An object of the present invention is to provide a method for producing a sheet-like product having a good surface quality and a good texture.

  Furthermore, the sheet-like material obtained by the artificial leather of the present invention is a material in which a PU porous structure is achieved by applying a water-dispersed PU.

  The present invention is to achieve the above-mentioned problem, and the method for producing a sheet-like product of the present invention comprises a fibrous base material, a water-dispersed polyurethane liquid, a foaming agent, an anionic surfactant, and / or A method for producing a sheet-like material, comprising applying a polyurethane liquid containing a zwitterionic surfactant.

  According to the preferable aspect of the manufacturing method of the sheet-like material of this invention, it is that the said polyurethane liquid contains a foam stabilizer further.

  According to a preferred embodiment of the method for producing a sheet-like product of the present invention, the foam stabilizer is a nonionic surfactant and / or a zwitterionic surfactant.

  According to a preferred embodiment of the method for producing a sheet-like product of the present invention, the foam stabilizer is an alkyl alkanolamide and / or an amine oxide.

  According to a preferred embodiment of the method for producing a sheet-like product of the present invention, the water-dispersed polyurethane is a self-emulsifying polyurethane.

  According to a preferred embodiment of the method for producing a sheet-like material of the present invention, the heat-sensitive coagulation temperature of the water-dispersed polyurethane liquid is 40 ° C. or higher and 95 ° C. or lower.

  According to the preferable aspect of the manufacturing method of the sheet-like material of this invention, the said fiber base material is a fabric which consists of an ultrafine fiber expression type fiber.

  According to the present invention, a PU porous structure can be expressed inside the sheet-like material regardless of the type of foaming agent and polyurethane by an environmentally friendly manufacturing process, which is as uniform as artificial leather to which organic solvent-based polyurethane is applied. It is possible to provide a method for producing a sheet-like product comprising a raised length and having an elegant surface quality excellent in fiber denseness and a good texture which is flexible and excellent in resilience.

FIG. 1 is a drawing-substituting photograph for explaining the porous structure of polyurethane, showing a cross section parallel to the thickness direction of the sheet-like material obtained in Example 2 of the present invention. FIG. 2 is a drawing-substituting photograph for illustrating that the polyurethane is not porous, showing a cross section parallel to the thickness direction of the sheet-like material obtained in Comparative Example 2.

  The present invention applies an environmentally-friendly water-dispersible polyurethane, and by adding a foaming agent and a specific surfactant to the water-dispersible polyurethane liquid, regardless of the type of the foaming agent and the water-dispersible polyurethane, Porous structure of water-dispersed polyurethane, with a uniform raised length equivalent to artificial leather to which organic solvent-based polyurethane is applied, elegant surface quality with excellent fiber denseness, and soft texture with excellent resilience The manufacturing method of the sheet-like material which has can be provided.

As the fibrous base material used in the present invention, fabrics such as woven fabrics, knitted fabrics and nonwoven fabrics can be preferably employed.
Especially, since the surface quality of the sheet-like thing at the time of surface raising treatment is favorable, a nonwoven fabric is used preferably. In the fibrous base material of the present invention, these woven fabrics, knitted fabrics, nonwoven fabrics and the like can be appropriately laminated and used together.

  The nonwoven fabric used in the present invention may be either a short-fiber nonwoven fabric or a long-fiber nonwoven fabric, but a short-fiber nonwoven fabric is preferably used in that a surface quality consisting of a uniform raised length can be obtained.

  The fiber length of the short fiber in the short fiber nonwoven fabric is preferably 25 mm to 90 mm, more preferably 35 mm to 75 mm. By setting the fiber length to 25 mm or more, a sheet-like material having excellent wear resistance can be obtained by entanglement. Further, by making the fiber length 90 mm or less, a sheet-like product having a higher quality can be obtained.

  Examples of fibers constituting the fibrous base material include polyethylene terephthalate, polybutylene terephthalate, polyester such as polytrimethylene terephthalate and polylactic acid, polyamide such as 6-nylon and 66-nylon, acrylic, polyethylene, polypropylene, and thermoplastic cellulose. A fiber made of a thermoplastic resin that can be melt-spun such as can be used. Among these, polyester fibers are preferably used from the viewpoints of strength, dimensional stability, and light resistance. The fibrous base material may be configured by mixing fibers of different materials.

  The cross-sectional shape of the fiber used in the present invention may be a round cross-section, but may be a polygonal shape such as an ellipse, a flat shape, and a triangular shape, or an irregular cross-section shape such as a sector shape and a cross shape.

  The average fiber diameter of the fibers constituting the fibrous base material is preferably 0.3 to 7 μm, and more preferably 0.8 to 5 μm. By making the average fiber diameter of the fibers 7 μm or less, the feel of the fibrous base material becomes more flexible. On the other hand, when the average fiber diameter of the fibers is 0.3 μm or more, the color developability after dyeing is further improved.

  In the present invention, when the fibrous base material is a nonwoven fabric, a woven fabric or a knitted fabric may be combined with the nonwoven fabric for the purpose of improving the strength. The combination of a nonwoven fabric and a woven fabric or a knitted fabric may be any method such as laminating a woven fabric or a knitted fabric on the nonwoven fabric and inserting the nonwoven fabric into the nonwoven fabric. Among them, it is preferable to use a woven fabric from the viewpoint that improvement in form stability and strength can be expected.

  Examples of the single yarn (warp and weft) constituting the woven fabric or knitted fabric include single yarns made of synthetic fibers such as polyester fibers and polyamide fibers. From the standpoint of fastness to dyeing, the yarns finally form a fabric such as a nonwoven fabric. The material is preferably the same material as the ultrafine fiber.

  Examples of the form of such a single yarn include filament yarn and spun yarn, but these strongly twisted yarns are preferably used. In addition, filament yarn is preferably used for the spun yarn because it causes surface fluff to fall off.

  When using a strongly twisted yarn, the number of twists is preferably 1000 T / m or more and 4000 T / m or less, more preferably 1500 T / m or more and 3500 T / m or less. If the number of twists is less than 1000 T / m, the number of single fibers constituting the strong twisted yarn by needle punching increases, and the physical properties of the product tend to deteriorate and the exposure of the single fibers to the product surface tends to increase. Moreover, when the number of twists is greater than 4000 T / m, the single fiber breakage is suppressed, but the strong twisted yarns constituting the woven fabric and the knitted fabric become too hard, and thus tend to cause hardening of the texture.

  The diameter of the strong twisted yarn is preferably 80 μm or more and 200 μm or less, and more preferably 120 μm or more and 180 μm or less. When the diameter of the single twisted yarn is smaller than 80 μm, the distortion of the woven fabric or the knitted fabric at the time of shrinkage in the dyeing process becomes large. In addition, when the diameter of the single twisted yarn is larger than 200 μm, the distortion of the woven fabric or knitted fabric in the dyeing process can be suppressed, but the entanglement between the nonwoven fabric web and the woven fabric or knitted fabric by the needle punching process becomes insufficient, and the product form stability Show a tendency to decrease.

  The single fiber fineness constituting the strongly twisted yarn is preferably 0.5 μm or more and 20.0 μm or less, more preferably 2.0 μm or more and 15.0 μm or less. When the single fiber fineness is smaller than 0.5 μm, the single fiber is frequently cut by the needle punching process, which is not preferable in terms of deterioration of physical properties of the product. In addition, if the single fiber fineness is larger than 20.0 μm, due to the difference in dyeability with the ultrafine fibers constituting the nonwoven fabric, the exposure of the fibers constituting the woven fabric or knitted fabric to the product surface is conspicuous, and the product quality tends to decrease. Show.

  Moreover, in this invention, it is a preferable aspect to use an ultrafine fiber expression type fiber for a fibrous base material. By using the ultrafine fiber expression type fiber for the fibrous base material, it is possible to stably obtain a form in which the bundle of ultrafine fibers described above is entangled.

  When the fibrous base material is a non-woven fabric, the non-woven fabric preferably has a structure in which bundles of ultrafine fibers (fiber bundles) are intertwined. Since the ultrafine fibers are entangled in a bundle state, the strength of the sheet-like material is improved. The nonwoven fabric of such an embodiment can be obtained by causing the ultrafine fibers to develop after entanglement of the ultrafine fiber-expressing fibers in advance.

  As the ultrafine fiber expression type fiber, two-component thermoplastic resins with different solvent solubility are used as a sea component and an island component, and the sea component is dissolved and removed using a solvent or the like to form an island component as an ultra-fine fiber. It is possible to employ a peelable composite fiber that splits fibers into ultrafine fibers by alternately arranging fibers or two-component thermoplastic resin radially or in a multilayer shape on the fiber cross section, and separating and separating each component.

  Among them, the sea-island type composite fiber can be used preferably also from the viewpoint of the flexibility and texture of the sheet-like material because it can provide an appropriate gap between the island components, that is, between the ultrafine fibers, by removing the sea component. It is done.

  For the sea-island type composite fiber, a sea-island type composite base is used, and the sea-island type composite fiber, in which two components of the sea component and the island component are arranged and spun together, and the two components of the sea component and the island component are mixed and spun Although there are mixed spun fibers, sea-island type composite fibers are preferably used from the viewpoint that ultrafine fibers having a uniform fineness can be obtained and that a sufficiently long ultrafine fiber is obtained and contributes to the strength of the sheet-like material.

  As the sea component of the sea-island composite fiber, polyethylene, polypropylene, polystyrene, copolymer polyester obtained by copolymerizing sodium sulfoisophthalic acid, polyethylene glycol, or the like, polylactic acid, polyvinyl alcohol, or the like can be used. Among them, a copolymerized polyester obtained by copolymerizing alkali-decomposable sodium sulfoisophthalic acid or polyethylene glycol that can be decomposed without using an organic solvent, polylactic acid, and hot water-soluble polyvinyl alcohol are preferably used.

  As for the ratio of the sea component to the island component of the sea-island type composite fiber, the mass ratio of the island fiber to the sea-island type composite fiber is preferably 0.2 to 0.8, more preferably 0.3 to 0.7. . By setting the mass ratio to 0.2 or more, the sea component removal rate is reduced, and the productivity is further improved. In addition, by setting the mass ratio to 0.8 or less, it is possible to improve the spreadability of the island fibers and prevent the island components from joining. The number of islands can be adjusted as appropriate according to the design of the base.

  The single fiber fineness of the ultrafine fiber expression type fiber such as sea-island type composite fiber is preferably 5 to 80 μm, more preferably 10 to 50 μm. If the single fiber fineness is smaller than 5 μm, the strength of the fiber is weak, and there is a tendency that single fiber breakage increases due to the needle punching process described later. In addition, when the single fiber fineness is larger than 80 μm, efficient entanglement may not be possible by needle punch processing or the like.

  As a method of obtaining a nonwoven fabric as a fibrous base material used in the present invention, a method of entanglement of a fiber web by a needle punching process or a water jet punching process, a spunbond method, a melt blow method, a papermaking method, or the like is adopted. In particular, in order to obtain the above-described ultrafine fiber bundle mode, a method that undergoes processing such as needle punching or water jet punching is preferably used.

  In addition, a needle punching process or a water jet punching process is preferably used for lamination and integration of a nonwoven fabric used as a fibrous base material and a woven fabric or a knitted fabric from the viewpoint of fiber entanglement. Among them, the needle punching treatment is not limited to the sheet thickness, and is preferably used because the fibers can be oriented in the vertical direction of the fibrous base material.

  The needle used in the needle punching process preferably has 1 to 9 barbs. By making the number of barbs one or more, efficient fiber entanglement becomes possible. On the other hand, fiber damage can be suppressed by setting the number of barbs to 9 or less. When the number of barbs is more than 9, fiber damage increases, and needle marks may remain on the fibrous base material, resulting in poor appearance of the product.

  Considering the influence on the fiber entanglement and the appearance of the product, the total depth of the barb (length from the barb tip to the barb bottom) is preferably 0.05 to 0.10 mm. By setting the total depth of the barb to 0.05 mm or more, a sufficient catch on the fiber bundle can be obtained, so that efficient fiber entanglement is possible. Further, if the total depth of the barb is larger than 0.10 mm, the fiber is often brought into the fibrous base material, but the needle mark remains on the fibrous base material, and the quality tends to be lowered. Considering the balance between the strength of the barb portion and the fiber entanglement, the total depth of the barb is preferably 0.06 mm or more and 0.08 mm or less.

In addition, when the nonwoven fabric and the woven fabric or knitted fabric are entangled and integrated, the nonwoven fabric is preliminarily entangled. This is a desirable mode for further prevention. As described above, when a method of preliminarily entangling by the needle punching process is adopted, it is effective to perform the punch density at 20 / cm ² or more, and preferably 100 / Pre-entanglement is preferably given at a punch density of cm ² or more, more preferably pre-entanglement is given at a punch density of 300 / cm ^{2 to} 1300 / cm ² .

When the preliminary entanglement is a punch density of less than 20 pieces / cm ² , the width of the non-woven fabric leaves room for narrowing due to the needle punch process at the time of entanglement with the woven fabric or the knitted fabric and thereafter, the width. This is because wrinkles may occur in the woven fabric or knitted fabric, and a smooth fibrous base material may not be obtained. Further, when the punch density of the preliminary entanglement is higher than 1300 / cm ² , generally the entanglement of the nonwoven fabric itself proceeds so much that the entanglement with the fibers constituting the woven fabric or the knitted fabric is sufficiently formed. This is because there is less room, which is disadvantageous for realizing a non-separated integrated structure in which the nonwoven fabric and the woven or knitted fabric are intertwined firmly.

In the present invention, regardless of the presence or absence of woven fabric or knitted fabric, when the fibers are entangled by the needle punching process, the punch density range is preferably 300 / cm ^{2 to} 6000 / cm ^2, and 1000 / it is more preferred embodiments of the cm ² to 3000 present / cm ^2.

  For entanglement of nonwoven fabric and woven fabric or knitted fabric, fabric or knitted fabric is laminated on one or both sides of the nonwoven fabric, or woven fabric or knitted fabric is sandwiched between multiple nonwoven fabrics, and fibers are entangled by needle punching. It can be a quality substrate.

  Moreover, when performing a water jet punch process, it is preferable to perform water in the state of a columnar flow. Specifically, it is preferable to eject water from a nozzle having a diameter of 0.05 to 1.0 mm at a pressure of 1 to 60 MPa.

The apparent density of the nonwoven fabric composed of ultrafine fiber-generating fibers after needle punching or water jet punching is preferably 0.15 to 0.450 g / cm ³ , more preferably 0.200 to 0.300 g / cm ³ . By setting the apparent density to 0.15 g / cm ³ or more, an artificial leather having sufficient form stability and dimensional stability can be obtained. On the other hand, when the apparent density is 0.450 g / cm ³ or less, a sufficient space for applying the polymer elastic body can be maintained.

  From the viewpoint of densification, it is preferable that the nonwoven fabric made of the ultrafine fiber-generating fibers thus obtained is shrunk by dry heat or wet heat or both, and further densified.

  The sea removal treatment when the sea-island type composite fiber is used may be performed before or after the application of the polyurethane liquid containing the water-dispersed polyurethane liquid to the fibrous base material. When the sea removal treatment is performed before the polyurethane is applied, the water-dispersed polyurethane is in close contact with the ultrafine fibers so that the ultrafine fibers can be firmly held, so that the wear resistance of the sheet-like material is improved. On the other hand, when sea removal treatment is performed after polyurethane is applied, voids are generated between the water-dispersed polyurethane and the ultrafine fibers due to the sea component removed from the sea, so the water-dispersible polyurethane does not directly grip the ultrafine fibers. In addition, the texture of the sheet-like material becomes flexible.

  The sea removal treatment can be performed by immersing a fibrous base material containing sea-island type composite fibers in a solvent and squeezing it. As the solvent for dissolving the sea component, when the sea component is polyethylene, polypropylene and polystyrene, an organic solvent such as toluene or trichloroethylene is used. When the sea component is a copolyester or polylactic acid, a sodium hydroxide aqueous solution is used. When the sea component is polyvinyl alcohol, hot water can be used.

  The thickness of the fibrous base material is preferably 0.3 mm or more and 6.0 mm or less, and more preferably 1.0 mm or more and 3.0 mm or less. If the thickness of the fibrous base material is less than 0.3 mm, the sheet form stability may be poor. On the other hand, when the thickness is larger than 6.0 mm, needle breakage tends to occur frequently in the needle punching process.

  The water-dispersed polyurethane used in the present invention is preferably one obtained by reaction of a polymer diol, an organic diisocyanate, and a chain extender.

  As the polymer diol, for example, polycarbonate-based diol, polyester-based diol, polyether-based diol, silicone-based diol, and fluorine-based diol can be adopted, and a copolymer obtained by combining these may be used. Of these, polycarbonate diols and polyether diols are preferably used from the viewpoint of hydrolysis resistance. From the viewpoints of light resistance and heat resistance, it is preferable to use a polycarbonate diol and a polyester diol. From the viewpoint of all the balances of hydrolysis resistance, heat resistance and light resistance, polycarbonate diols and polyester diols are more preferred, and polycarbonate diols are particularly preferred.

  The polycarbonate-based diol can be produced by an ester exchange reaction between an alkylene glycol and a carbonate ester, or a reaction between phosgene or chloroformate ester and an alkylene glycol.

  Examples of alkylene glycols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, and 1,10-decanediol. Chain alkylene glycol, branched alkylene glycol such as neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-methyl-1,8-octanediol, Alicyclic diols such as 1,4-cyclohexanediol, aromatic diols such as bisphenol A, glycerin, trimethylolpropane, and pentaerythritol. Either a polycarbonate diol obtained from a single alkylene glycol or a copolymerized polycarbonate diol obtained from two or more types of alkylene glycols may be used.

  Examples of the polyester diol include polyester diols obtained by condensing various low molecular weight polyols and polybasic acids.

  Examples of the low molecular weight polyol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, and 2,2-dimethyl-1,3-propane. Diol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, cyclohexane-1,4-diol, and One kind or two or more kinds selected from cyclohexane-1,4-dimethanol can be used. Further, addition products obtained by adding various alkylene oxides to bisphenol A can also be used.

  Polybasic acids include, for example, succinic acid, maleic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, and hexahydro One kind or two or more kinds selected from isophthalic acid can be mentioned.

  Examples of polyether-based diols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and copolymerized diols combining them.

  The number average molecular weight of the polymer diol is preferably 500 to 4000. By making the number average molecular weight 500 or more, more preferably 1500 or more, it is possible to prevent the texture from becoming hard, and by making the number average molecular weight 4000 or less, more preferably 3000 or less, the strength as polyurethane is increased. Can be maintained.

  Examples of the organic diisocyanate include aliphatic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and xylylene diisocyanate, and aromatic diisocyanates such as diphenylmethane diisocyanate and tolylene diisocyanate, and combinations thereof. May be used. Among these, aliphatic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and isophorone diisocyanate are preferably used from the viewpoint of light resistance.

  As the chain extender, amine chain extenders such as ethylenediamine and methylenebisaniline and diol chain extenders such as ethylene glycol can be used. Moreover, the polyamine obtained by making polyisocyanate and water react can also be used as a chain extender.

  The water-dispersed polyurethane used in the present invention may be used in combination with a crosslinking agent for the purpose of improving water resistance, abrasion resistance, hydrolysis resistance and the like. The cross-linking agent may be an external cross-linking agent added as a third component to the water-dispersible polyurethane, or may be an internal cross-linking agent that introduces a reaction point that becomes a cross-linked structure in advance in the water-dispersible polyurethane molecular structure. It is preferable to use an internal cross-linking agent from the viewpoint that the cross-linking points can be formed more uniformly in the water-dispersible polyurethane molecular structure and the reduction in flexibility can be reduced.

  As the crosslinking agent, compounds having an isocyanate group, an oxazoline group, a carbodiimide group, an epoxy group, a melamine resin, a silanol group, and the like can be used. However, when the crosslinking proceeds excessively, the water-dispersed polyurethane tends to harden and the texture of the sheet-like material tends to harden, so that those having a silanol group are preferably used in terms of the balance between reactivity and flexibility. In addition, the water-dispersed polyurethane used in the present invention preferably has a hydrophilic group in the molecular structure. By having a hydrophilic group in the molecular structure, the dispersion / stability of the water-dispersed polyurethane can be improved.

  Examples of the hydrophilic group include cationic systems such as quaternary amine salts, anionic systems such as sulfonates and carboxylates, nonionic systems such as polyethylene glycol, and combinations of cationic and nonionic systems, and anionic and nonionic systems. Any hydrophilic group of the combination of systems can be employed. Among these, it is a particularly preferable embodiment that has a nonionic hydrophilic group in the molecular structure, which is free from yellowing caused by light and harmful effects caused by a neutralizing agent.

  That is, in the case of an anionic hydrophilic group, a neutralizing agent is required. For example, the neutralizing agent is a tertiary amine such as ammonia, triethylamine, triethanolamine, triisopropanolamine, trimethylamine and dimethylethanolamine. In some cases, amines are generated and volatilized by heat generated during film formation and drying, and are released outside the system. For this reason, in order to suppress the release of air and the deterioration of the working environment, it is essential to introduce a device for recovering volatile amines. In addition, if the amine does not volatilize by heating and remains in the final product sheet, it may be discharged to the environment when the product is incinerated. On the other hand, in the case of a nonionic hydrophilic group, since no neutralizing agent is used, it is not necessary to introduce an amine recovery device, and there is no fear of remaining amine in the sheet.

  In addition, when the neutralizing agent is an alkali metal such as sodium hydroxide, potassium hydroxide or calcium hydroxide, or a hydroxide of an alkaline earth metal, the water-dispersible polyurethane portion exhibits alkalinity when wetted with water. However, in the case of a nonionic hydrophilic group, since a neutralizing agent is not used, there is no need to worry about degradation of the water-dispersed polyurethane due to hydrolysis.

  In the water-dispersed polyurethane, the 100% modulus of the dry film is preferably 2 MPa or more and 8 MPa or less, more preferably 3 MPa or more and 6 MPa or less. When the 100% modulus of the dry film is within this range, the texture and abrasion resistance of the water-dispersed polyurethane sheet are improved. The 100% modulus is an index representing the hardness of the water-dispersed polyurethane, and the 100% modulus is the ratio of the hard segment structure caused by isocyanate or chain extender in the water-dispersed polyurethane molecular structure, polyol, isocyanate, etc. It can be adjusted according to the type. If the 100% modulus is less than 2 MPa, the water-dispersed polyurethane is too flexible, and the fiber material impregnated with the polyurethane liquid has less rebound. On the other hand, when the 100% modulus is greater than 8 MPa, the water-dispersed polyurethane is hard, and even if the water-dispersed polyurethane has a porous structure, the sheet-like material tends to remain hard.

  The water-dispersed polyurethane liquid used in the present invention includes a forced emulsification type polyurethane that is forcibly dispersed and stabilized using a surfactant, a hydrophilic structure in the polyurethane molecular structure, and a surfactant is present. Even if not, it is classified as a self-emulsifying type polyurethane that is dispersed and stabilized in water. Any of these may be used in the present invention, but a self-emulsifying type polyurethane is preferably used in that no heat-sensitive coagulant is required at the time of heat-sensitive coagulation of the water-dispersed polyurethane.

  Here, the heat-sensitive coagulation refers to the property that when a water-dispersed polyurethane liquid is heated and reaches a certain temperature (heat-sensitive coagulation temperature), the fluidity of the polyurethane liquid decreases and solidifies (the property that the polyurethane molecules aggregate). Say. When this heat-sensitive coagulation property is not exhibited, the water-dispersed polyurethane liquid impregnated in the fibrous base material causes a migration migration phenomenon on the surface layer of the fibrous base material along with water evaporation during dry solidification, and the water-dispersed polyurethane is attached. The texture of the sheet-like material tends to harden. The thermal coagulation temperature is preferably 40 ° C. or higher and 95 ° C. or lower. By setting the heat-sensitive coagulation temperature to 40 ° C. or more, stability during storage of the water-dispersed polyurethane liquid is improved, and adhesion of the water-dispersed polyurethane to the machine during operation can be suppressed. Moreover, the migration phenomenon of the water dispersion type polyurethane in a fibrous base material can be suppressed by making a thermal coagulation temperature into 95 degrees C or less.

  In general, the forced emulsification type polyurethane is formed by adding a nonionic surfactant in an amount of 2.0% by mass to 15% by mass with respect to the mass of polyurethane to form an emulsion. To this water-dispersed polyurethane liquid, a heat-sensitive coagulant such as an inorganic salt such as sodium sulfate, magnesium sulfate, calcium sulfate, calcium chloride, sodium persulfate, potassium persulfate, ammonium persulfate, azobisisobutyronitrile, Radical reaction initiators such as benzoyl oxide are added to destabilize and disperse the water-dispersed polyurethane emulsion, thereby agglomerating nonionic surfactants and disrupting the water dispersion of the water-dispersed polyurethane. Type polyurethane is agglomerated (heat-sensitive coagulation). On the other hand, self-emulsifying polyurethane is dispersed in water due to hydration of hydrophilic groups incorporated in the molecule. By heating it, the hydrophilic groups are aggregated, the aqueous dispersion of the water-dispersed polyurethane is disrupted, and the water-dispersed polyurethane is aggregated (heat-sensitive coagulation).

  As described above, the forced emulsification type polyurethane makes the water-dispersed polyurethane emulsion uneasy due to the addition of the heat-sensitive coagulant, so it is difficult to store for a long time after the addition of the heat-sensitive coagulant. Self-emulsifying polyurethane is preferred.

  In addition, the concentration of the water-dispersible polyurethane (content of the water-dispersible polyurethane with respect to the water-dispersible polyurethane liquid) is preferably 5% by mass or more and 60% by mass or less from the viewpoint of storage stability of the water-dispersible polyurethane liquid. Preferably they are 10 mass% or more and 30 mass% or less. When the concentration of the water-dispersed polyurethane liquid is less than 5% by mass, when impregnated into the fibrous base material, the amount of water evaporated in the coagulation and drying process of the polyurethane is large, and the polyurethane easily moves to the surface layer of the sheet as the water evaporates. Become. On the other hand, when the concentration is higher than 60% by mass, the polyurethane emulsion tends to aggregate, so that it may not be stored for a long time. The water-dispersed polyurethane liquid means an aqueous solution in which water-dispersed polyurethane is dispersed in water. Furthermore, a liquid obtained by adding an additive to a water-dispersed polyurethane liquid for the purpose of forming a PU porous structure is distinguished as a polyurethane liquid.

  The polyurethane liquid used in the present invention contains a water-dispersed polyurethane liquid, a foaming agent, and an anionic and / or zwitterionic surfactant different from the polyurethane emulsifier.

  The foaming agent refers to an additive that generates a nitrogen gas or the like by causing a chemical reaction such as decomposition when heated. By using a water-dispersed polyurethane liquid containing a foaming agent, the water-dispersible polyurethane liquid is applied to the fibrous base material, and when heated, the foaming agent is decomposed to generate bubbles composed of the generated gas.

  The inventors of the present invention have made extensive studies, and in addition to the foaming agent, by adding a surfactant having excellent foaming properties, the surface tension is reduced, coalescence of the generated bubbles is prevented, and the deaeration time of the generated bubbles is reduced. By delaying this, a porous structure of water-dispersed polyurethane is realized regardless of the type of polyurethane and foaming agent.

  Examples of the blowing agent used in the present invention include azobisformamide, azodicarbonamide, barium azodicarboxylate, azobisisobutyronitrile, diazobenzene, diazoaminobenzene, azohexahydrobenzodinitrile, azobisdimethylvaleronitrile. 1,1′-azobis (cyclohexane-1-carbodinitrile), 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis {2- [1- (2-hydroxylethyl) -2-imidazolin-2-yl] propane}, 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine], 2,2′-azobis (1- Imino-1-pyrrolidino-2-methylpropane), and 2,2′-azobis [2-methyl-N (2- Rokishiechiru) azo compounds such as propionamide may be used. These may be used in the form of a salt with an inorganic acid such as hydrochloric acid or sulfuric acid for the purpose of improving the solubility in water, or may be used in the form of a hydrate. .

  The content of the foaming agent contained in the polyurethane liquid used in the present invention is preferably 0.5% by mass or more and 20% by mass or less with respect to the water-dispersed polyurethane solid content. If the content of the foaming agent is too small, foaming is insufficient and the texture of the sheet-like material becomes hard, and if it is too much, the foaming is too much and the wear resistance of the sheet-like material is reduced. More preferably, it is 1 mass% or more and 15 mass% or less.

  The foaming agent is a compound that decomposes by heat and generates a gas, and preferably has a 10-hour half-life temperature of 30 ° C. to 110 ° C. The initial temperature is more preferably 40 ° C to 100 ° C. If the 10-hour half-life temperature is lower than 30 ° C., the progress of decomposition is relatively fast even at room temperature, so that the concentration of undecomposed blowing agent in the prepared solution decreases every moment. For this reason, it is necessary to store the prepared solution at a low temperature and to increase the frequency of solution preparation. Further, if the 10-hour half-life temperature is higher than 110 ° C., it is necessary to add a large amount of a foaming agent in order to generate a gas amount necessary for making the polyurethane into a porous structure, and heat treatment at a high temperature In addition, since it is necessary to perform a heat treatment for a long time, not only the polyurethane is deteriorated due to thermal decomposition but also disadvantageous in terms of manufacturing cost.

  The surfactant used in the present invention is an anionic surfactant or an amphoteric surfactant excellent in foaming properties.

  Specifically, examples of the anionic surfactant include carboxylates such as soaps, sulfates such as higher alcohol sulfates, higher alkyl ether sulfates, sulfated oils, sulfated fatty acid esters and sulfated olefins. In addition, sulfonic acid salts such as alkylbenzene sulfonates, alkylnaphthalene sulfonates, paraffin sulfonates, aerosols, and phosphoric acid ester salts can be applied.

  In addition to amphoteric surfactants, carboxylate types such as amino acid type amphoteric surfactants and betaine type amphoteric surfactants, sulfate ester types, sulfonate ester types, and phosphate esters An amphoteric surfactant such as a salt form can be applied.

  Moreover, you may combine the above-mentioned anionic surfactant and amphoteric surfactant suitably.

  On the other hand, examples of cationic surfactants include alkyltrimethylammonium salts, dialkyldimethylammonium salts, and alkyldimethylbenzylammonium salts, but many of them contain halogen atoms, and the surface tension of water-dispersed polyurethane liquids is expected to decrease. Although it is possible, it is not preferable in terms of environmental considerations.

  In addition, nonionic surfactants include polyhydric alcohol types such as polyethylene glycol type nonionic surfactants such as higher alcohol ethylene oxide adducts and fatty acid ethylene oxide adducts, and fatty acid esters of glycerol and fatty acid amides of alkanolamines. Nonionic surfactants may be mentioned, but when applied as a nonionic surfactant alone, there is little effect on reducing ionic surfactants, foaming power and surface tension, compared with ionic surfactants, and a large amount of addition. Is not preferable in terms of cost increase.

  However, by combining a nonionic surfactant with the above-mentioned anionic surfactant and / or amphoteric surfactant, foaming properties can be increased with a small amount of addition, so other types of surfactants May be used in combination.

  A more preferable embodiment of the surfactant used in the present invention is to combine an anionic and / or amphoteric surfactant with a surfactant which is a foam stabilizer. By combining a surfactant having excellent foam stability, foam generated in the water-dispersed polyurethane liquid can be more stably present, and the porous structure of the water-dispersed polyurethane can be promoted.

  Examples of the surfactant having a foam stabilizing effect include alkyl alkanolamides such as coconut oil fatty acid N-methylethanolamide and coconut oil fatty acid diethanolamide which are nonionic surfactants, and lauryl dimethyl which is a zwitterionic surfactant. Amine oxide such as amine oxide can be applied.

  The content of the anionic surfactant and / or the zwitterionic surfactant contained in the polyurethane liquid other than the emulsifier of the water-dispersed polyurethane is 0.05% by mass or more in comparison with the water-dispersed polyurethane solid content. The content is preferably 0% by mass or less, more preferably 0.3% by mass or more and 2.0% by mass or less. If the surfactant content is less than 0.05%, the porous structure of the polyurethane is insufficient and the texture of the sheet becomes hard. If the content exceeds 5.0% by mass, an emulsion of water-dispersed polyurethane May stabilize, the thermal coagulation temperature will rise, and migration of water-dispersed polyurethane may be induced.

  The water-dispersed polyurethane liquid and polyurethane liquid used in the present invention include various additives, for example, pigments such as carbon black, flame retardants such as phosphorus-based, halogen-based, silicone-based and inorganic-based, phenol-based, sulfur-based And phosphorous antioxidants, UV absorbers such as benzotriazoles, benzophenones, salicylates, cyanoacrylates and oxalic acid anilides, light stabilizers such as hindered amines and benzoates, polycarbodiimides, etc. Hydrolysis-resistant stabilizers, plasticizers, antistatic agents, softeners, water repellents, coagulation modifiers, dyes, preservatives, antibacterial agents, and fillers such as deodorants may be contained.

  The water-dispersed polyurethane liquid may contain a water-soluble organic solvent in an amount of 40% by mass or less based on the water-dispersed polyurethane liquid in order to improve storage stability and film-forming properties. In view of the above, the content of the organic solvent is preferably 1% by mass or less.

  The water-dispersed polyurethane can be coagulated by impregnating and applying a polyurethane liquid to a fibrous base material, and dry heat coagulation, wet heat coagulation, wet coagulation, or a combination thereof.

  When wet heat coagulation is performed, the wet heat coagulation temperature may be not less than the heat sensitive coagulation temperature of the water-dispersed polyurethane, and is preferably 40 ° C. or more and 200 ° C. or less, for example. By setting the wet heat solidification temperature to 40 ° C. or higher, more preferably 80 ° C. or higher, the time to solidification of the water-dispersed polyurethane can be shortened to further suppress the migration phenomenon. On the other hand, by setting the wet heat solidification temperature to 200 ° C. or lower, more preferably 160 ° C. or lower, the thermal degradation of the water-dispersed polyurethane can be controlled.

  The temperature of wet coagulation may be not less than the heat-sensitive coagulation temperature of water-dispersed polyurethane, and is preferably 40 ° C. or more and 100 ° C. or less, for example. By setting the temperature of wet coagulation in hot water to 40 ° C. or higher, more preferably 80 ° C. or higher, the time to solidification of the water-dispersed polyurethane can be shortened to further suppress the migration phenomenon.

  The dry solidification temperature and the drying temperature are preferably 80 ° C. or higher and 160 ° C. or lower. By setting the dry solidification temperature and the drying temperature to 80 ° C. or higher, more preferably 90 ° C. or higher, the productivity is excellent. On the other hand, by setting the dry coagulation temperature and the drying temperature to 180 ° C. or less, more preferably 160 ° C. or less, the thermal degradation of the water-dispersed polyurethane can be controlled.

  The ratio of the water-dispersed polyurethane to the sheet-like material obtained by the present invention is preferably 10 to 80% by mass. By setting the ratio of the water-dispersible polyurethane to 10% by mass or more, more preferably 15% by mass or more, it is possible to obtain sufficient strength to the sheet-like material and to prevent the fibers from falling off. Moreover, by setting the ratio of the water-dispersed polyurethane to 80% by mass or less, more preferably 70% by mass or less, it is possible to prevent the texture of the sheet-like material from becoming hard and to obtain good napped quality.

  The PU porous structure is shown here. FIG. 1 shows a cross section parallel to the thickness direction of the sheet-like material of Example 2 in which a surfactant and a foaming agent are added to achieve a PU porous structure. FIG. 2 shows a cross section parallel to the thickness direction of the sheet-like material of Comparative Example 2 in which only the foaming agent is added.

  In FIG. 1, the gap between the ultrafine fiber bundle and the polyurethane is large (PU porous structure). On the other hand, in FIG. 2, there is no gap between the ultrafine fiber bundle and the polyurethane, and the polyurethane is firmly bonded to the ultrafine fiber bundle. This structural difference, that is, the PU porous structure, increases the degree of freedom of the ultrafine fiber bundle and softens the texture.

  After the water-dispersible polyurethane is applied, dividing the water-dispersed polyurethane-applied sheet into half or several sheets in the sheet thickness direction is a preferable embodiment with excellent production efficiency.

  A lubricant such as a silicone emulsion may be applied to the water-dispersed polyurethane-applied sheet prior to the raising treatment described later. Moreover, applying an antistatic agent before the raising treatment is a preferable aspect in order to make it difficult for the grinding powder generated from the sheet-like material to be deposited on the sandpaper by grinding.

  In order to form napping on the surface of the sheet-like material, napping treatment may be performed. The raising treatment can be performed by a method of grinding using sandpaper, roll sander or the like.

  If the thickness of the sheet-like material is too thin, physical properties such as tensile strength and tearing strength of the sheet-like material will be weak, and if too thick, the texture of the sheet-like material will be hard, so about 0.1 to 5.0 mm Preferably there is.

  The sheet material may be dyed. As a dyeing method, it is preferable to use a liquid dyeing machine because the sheet-like material can be softened by dyeing the sheet-like material and at the same time giving a stagnation effect.

  If the dyeing temperature is too high, the water-dispersed polyurethane may be deteriorated. On the other hand, if the dyeing temperature is too low, the dyeing to the fiber becomes insufficient. Therefore, the dyeing temperature is preferably set depending on the type of the fiber. It is preferably not higher than ° C., more preferably 110 ° C. or higher and 130 ° C. or lower.

  The dye may be selected according to the type of fiber constituting the fibrous base material. For example, a disperse dye is used for a polyester fiber, an acid dye or a metal-containing dye is used for a polyamide fiber, and further Combinations thereof can be used. When dyed with disperse dyes, reduction washing may be performed after dyeing.

  It is also a preferred embodiment to use a dyeing assistant during dyeing. By using a dyeing assistant, the uniformity and reproducibility of dyeing can be improved. In addition, a finishing treatment using a softening agent such as silicone, an antistatic agent, a water repellent, a flame retardant, a light proofing agent, and an antibacterial agent can be performed in the same bath or after dyeing.

  The sheet-like material obtained by the present invention is mainly used as artificial leather, for example, as a skin material for furniture, chairs and wall materials, and seats, ceilings and interiors in vehicles such as automobiles, trains and aircraft. Interior materials with elegant appearance, shirts, jackets, casual shoes, sports shoes, men's shoes, women's shoes and other shoe uppers, trims, bags, belts, wallets, etc., and clothing materials used for some of them It can be suitably used as industrial materials such as wiping cloth, polishing cloth and CD curtain.

  Next, although the manufacturing method of the sheet-like material of this invention is demonstrated in detail according to an Example, this invention is not limited only to these Examples.

[Evaluation method]
(1) Average fiber diameter A cross section parallel to the thickness direction of the sheet (artificial leather) was observed with a scanning electron microscope (VE-7800 manufactured by SEM Keyence) at a magnification of 2000, and the observed fiber cross section was random. 100 were selected, the fiber diameter was measured, and the average value was calculated.

  When the ultrafine fiber constituting the fibrous base material or the sheet-like material has an irregular cross section, the outer peripheral circular diameter of the irregular cross section is calculated as the fiber diameter. In addition, when a circular cross section and an irregular cross section are mixed, or when fibers having greatly different fiber diameters are mixed, 100 are selected and calculated so that each has the same number.

(2) Presence of polyurethane porous structure inside sheet-like material (artificial leather) Cross section parallel to the thickness direction of sheet-like material (artificial leather) is 500 times with a scanning electron microscope (VE-7800 manufactured by SEM Keyence) In the fiber bundles observed in the 20 SEM images observed at random, the total number of fiber bundles is A, and the total number of fiber bundles to which polyurethane is not bonded is B. %) = B / A × 100. Here, the fiber to which polyurethane is not bonded means a fiber having a space of 10 μm or more from the outermost part of the ultrafine fiber bundle.

  In the sheet-like material (artificial leather) into which the woven fabric and / or the knitted fabric were inserted, the above-mentioned polyurethane porous structure was evaluated from the 20 SEM images in which the woven fabric and / or the knitted fabric were not observed, and the average value of 20 was calculated .

(3) Heat-sensitive coagulation temperature of water-dispersed polyurethane liquid After adding 20 ml of water-dispersed polyurethane liquid prepared with a solid content of water-dispersed polyurethane to 10% by mass to a test tube having an inner diameter of 12 mm, a thermometer was inserted. The test tube was sealed, immersed in a warm water bath at a temperature of 95 ° C., and the temperature at which the prepared solution lost fluidity was measured as the thermal coagulation temperature. The thermal coagulation temperature of 10 samples was measured, and the average value was taken as the thermal coagulation temperature.

(4) Texture of sheet-like material The texture of the sheet-like material is 10 pieces of 2 × 25 cm test pieces in the vertical direction based on the D method (heart loop method) described in JIS L1096-8.19.4 (1999). The test piece was attached to a horizontal bar grip in a heart loop shape so that the effective length of the test piece was 20 cm. Next, the distance L (cm) between the top of the horizontal bar and the lowest point of the loop after 1 minute was measured. Each test result (distance L) was averaged and evaluated as bending resistance (cm).

(5) Appearance quality of sheet-like material The appearance quality of sheet-like material is evaluated in five stages by visual and sensory evaluation as follows, with a total of 20 healthy adult men and 10 adult women each as an evaluator. The most common evaluation was the appearance quality. Appearance quality was graded 4-5.
Grade 5: There is uniform fiber napping, the fiber dispersion state is good, and the appearance is good.
Grade 4: Evaluation between grade 5 and grade 3.
Third grade: The dispersion state of the fibers is slightly poor, but there are fiber nappings and the appearance is reasonably good.
Second grade: An evaluation between the third grade and the first grade.
First grade: Overall, the fiber dispersion is very poor and the appearance is poor.

[Preparation of polyurethane liquid A]
As a water-dispersible polyurethane, a polyoxyethylene chain-containing polycarbonate-based self-emulsifying polyurethane liquid in which polyhexamethylene carbonate is applied to polyol and dicyclohexylmethane diisocyanate is applied to isocyanate is used as a foaming agent as a foaming agent. VA-086 "(manufactured by Wako Pure Chemical Industries, Ltd., 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) propionamide]) was added in 3 parts by mass, and a straight chain as a surfactant Add 0.6 part by mass of anionic surfactant “Neogen S-20F (registered trademark)” (Daiichi Kogyo Seiyaku Co., Ltd.) of sodium alkylbenzene sulfonate, and prepare with water to a PU solid content of 20% by mass. This was designated as polyurethane liquid A.

[Preparation of polyurethane liquid B]
In the preparation of polyurethane liquid A, instead of “Neogen S-20F (registered trademark)”, polyoxyethylene lauryl sodium sulfate anionic surfactant “Hitenol 227L (registered trademark)” was added to 100 mass of polyurethane solid content. A polyurethane liquid B was prepared in the same manner as the polyurethane liquid A except that 1.0 part by mass was added to the parts.

[Preparation of polyurethane liquid C]
In the preparation of the polyurethane liquid A, instead of “Neogen S-20F (registered trademark)”, the amphoteric surfactant “Amogen S-H (registered trademark)” of lauryldimethylaminoacetic acid betaine (Daiichi Kogyo Seiyaku ( Co., Ltd.) was added in the same manner as polyurethane liquid A except that 3.0 parts by mass of polyurethane solid content was added to 100 parts by mass of polyurethane solid content.

[Preparation of polyurethane liquid D]
In the preparation of the polyurethane liquid A, “Dyanol CDE (registered trademark)” (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) of palm oil fatty acid diethanolamide as a foam stabilizer is 0.3 mass with respect to 100 mass parts of polyurethane solid content. A polyurethane liquid D was prepared in the same manner as the polyurethane liquid A except that the components were added together.

[Preparation of polyurethane liquid E]
The polyurethane liquid C was prepared by adding “Dyanol CDE (registered trademark)” of palm oil fatty acid diethanolamide as a foam stabilizer in combination with 1.8 parts by mass with respect to 100 parts by mass of the polyurethane solid content. This was prepared in the same manner as liquid C, and this was designated as polyurethane liquid E.

[Preparation of polyurethane liquid F]
In preparation of polyurethane liquid A, instead of “VA-086” (manufactured by Wako Pure Chemical Industries, Ltd., 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide]) as a foaming agent In addition, “V-50” (manufactured by Wako Pure Chemical Industries, Ltd., 2,2′-azobis (2-methylpropionamide) dihydrochloride) was added in the same manner as polyurethane liquid A, except that 3 parts by mass was added. This was designated as polyurethane liquid F.

[Preparation of polyurethane liquid G]
In the preparation of polyurethane liquid A, “Neogen S-20F (registered trademark)” is combined with 0.2 parts by mass with respect to 100 parts by mass of polyurethane solid content, and both amphoteric surfactants “Amogen S-H (registered trademark)” are used. ”Was prepared in the same manner as the polyurethane liquid A except that 0.8 part by mass was added to 100 parts by mass of the polyurethane solid content.

[Preparation of polyurethane liquid H]
In the preparation of the polyurethane liquid C, the amphoteric surfactant “Amogen S-H (registered trademark)” is 1.0 part by mass with respect to 100 parts by mass of the polyurethane solid, and “Amphitol” of lauryldimethylamine oxide as a foam stabilizer. 20N (registered trademark) ”(manufactured by Kao Corporation) was prepared in the same manner as polyurethane liquid C, except that 0.5 parts by mass was added to 100 parts by mass of polyurethane solid content. It was.

[Preparation of polyurethane liquid I]
In the preparation of the polyurethane liquid D, instead of “Neogen S-20F (registered trademark)”, a nonionic surfactant “Neugen XL-70 (registered trademark)” of polyoxyethylene lauryl ether was added in 100 parts by mass of polyurethane solid content. A polyurethane liquid I was prepared in the same manner as the polyurethane liquid D except that 3.0 parts by mass was added to the polyurethane liquid D.

[Preparation of polyurethane liquid J]
In the preparation of the polyurethane liquid A, a polyurethane liquid J was prepared in the same manner as the polyurethane liquid A except that no surfactant was added.

[Preparation of polyurethane liquid K]
In preparing the polyurethane liquid F, a polyurethane liquid K was prepared in the same manner as the polyurethane liquid F except that no surfactant was added.

  Table 1 summarizes the compositions and properties of the polyurethane liquids A to I adjusted as described above.

[Preparation of polyurethane liquid L]
In preparing the polyurethane liquid J, a polyurethane liquid L was prepared in the same manner as the polyurethane liquid J except that no foaming agent was added.

  Table 1 shows the compositions and properties of the polyurethane liquid A to the polyurethane liquid L adjusted as described above.

[Example 1]
As the sea component, polyethylene terephthalate copolymerized with 8 mol% of sodium 5-sulfoisophthalate is used, and as the island component, polyethylene terephthalate is used. The sea component is 20% by mass, the island component is 80% by mass, and the number of islands is 16 / 1 filament, sea-island type composite fiber having an average fiber diameter of 20 μm was obtained. The obtained sea-island type composite fiber was cut into a fiber length of 51 mm to form a staple, a fiber web was formed through a card and a cross wrapper, and a nonwoven fabric was formed by needle punching.

  This nonwoven fabric was immersed in hot water at a temperature of 97 ° C. for 2 minutes to shrink and dried at a temperature of 100 ° C. for 5 minutes. Next, the obtained non-woven fabric was impregnated with the polyurethane liquid E prepared as described above, treated for 5 minutes in a moist and hot atmosphere at a temperature of 97 ° C. and a humidity of 100%, and then dried with hot air at a drying temperature of 120 ° C. for 15 minutes. A sheet provided with water-dispersed polyurethane was obtained so that the polyurethane mass relative to the mass was 35 mass%.

  Next, this sheet was immersed in a 10 g / L sodium hydroxide aqueous solution heated to 95 ° C. and treated for 25 minutes to obtain a sea-removed sheet from which sea components of the sea-island composite fibers were removed. The average fiber diameter on the surface of the obtained sea removal sheet was 4.2 μm. After that, using a half-cutting machine with an endless band knife, cut in half perpendicular to the thickness direction, grinding the non-half-cut side using 120-mesh and 240-mesh sandpaper, brushing, and circular dyeing The machine was dyed with disperse dye and washed by reduction to obtain artificial leather. As a result of observing a cross section parallel to the thickness direction of the obtained artificial leather with an SEM, a porous structure of water-dispersed polyurethane was obtained, and the appearance quality, texture and abrasion resistance of the sheet-like product were good.

[Examples 2 to 8]
In Example 1, artificial leather was obtained in the same manner as in Example 1 except that the polyurethane liquid E was changed to the polyurethane liquids A to H shown in Table 1 prepared above. As a result of observing a cross section parallel to the thickness direction of the obtained artificial leather with an SEM, a porous structure of water-dispersed polyurethane was obtained, and the appearance quality, texture and abrasion resistance of the sheet-like product were good.

[Example 9]
In Example 3, after removing the sea component of the sea-island type composite fiber with sodium hydroxide from the nonwoven fabric contracted by being immersed in hot water at a temperature of 97 ° C. for 2 minutes, it was carried out except that the polyurethane liquid A was impregnated. An artificial leather was obtained in the same manner as in Example 3. As a result of observing a cross section parallel to the thickness direction of the obtained artificial leather with an SEM, a porous structure of water-dispersed polyurethane was obtained, and the appearance quality, texture and abrasion resistance of the sheet-like product were good.

[Comparative Examples 1-4]
In Example 1, artificial leather was obtained in the same manner as in Example 1 except that the polyurethane liquid E was changed to the polyurethane liquids I to L shown in Table 1 prepared above. In Comparative Example 1 using the polyurethane liquid I, a surfactant was added, but as a result of observing a cross section parallel to the thickness direction of the obtained artificial leather with SEM, the porous structure of the water-dispersed polyurethane was insufficient. The texture was hard and the grindability in the raising process was poor, resulting in poor appearance quality. In Comparative Examples 2, 3 and 4 using the polyurethane liquid H and the polyurethane liquid I, since no surfactant was added, a cross section parallel to the thickness direction of the obtained artificial leather was observed with an SEM. The structure was insufficient, the texture was hard, and the grindability in the raising process was poor, resulting in poor appearance quality.

[Comparative Example 5]
In Comparative Example 2, the nonwoven fabric subjected to hot water shrinkage was impregnated with 1.5 parts by mass of an aqueous solution of a surfactant “Neogen S-20F” (registered trademark), then squeezed with a mangle, and the surface activity with respect to 100 parts by mass of the sheet. The agent was applied in an amount of 3.0 parts by mass and dried with hot air at a drying temperature of 120 ° C. for 5 minutes. Thereafter, artificial leather was obtained in the same manner as in Comparative Example 2 except that the nonwoven fabric was impregnated with polyurethane liquid J. As a result of observing a cross section parallel to the thickness direction of the obtained artificial leather with SEM, the porous structure of polyurethane is insufficient, the texture is hard, and the grindability in the raising process is deteriorated, resulting in poor appearance quality. It became.

  The results of Examples 1 to 9 and Comparative Examples 1 to 5 are collectively shown in Table 2.

Claims (8)

  A method for producing a sheet-like material, comprising applying a polyurethane liquid containing a water-dispersible polyurethane liquid, a foaming agent, an anionic surfactant and / or a zwitterionic surfactant to a fibrous base material.   The method for producing a sheet-like product according to claim 1, wherein the polyurethane liquid further contains a foam stabilizer.   The method for producing a sheet-like product according to claim 2, wherein the foam stabilizer is a nonionic surfactant and / or a zwitterionic surfactant.   The method for producing a sheet-like product according to claim 2 or 3, wherein the foam stabilizer is an alkyl alkanolamide and / or an amine oxide.   The method for producing a sheet-like product according to claim 1, wherein the water-dispersible polyurethane is a self-emulsifying polyurethane.   The method for producing a sheet-like product according to claim 1, wherein the heat-sensitive coagulation temperature of the water-dispersed polyurethane liquid is 40 ° C or higher and 95 ° C or lower.   2. The method for producing a sheet-like product according to claim 1, wherein the fibrous base material is a fabric made of ultrafine fiber-expressing fibers.   The method for producing a sheet-like product according to claim 7, wherein the fibrous base material is a fabric made of ultrafine fiber-expressing fibers before sea removal.