Artificial Leather and Production Method Therefor

Abstract

Provided is an artificial leather that has texture (stiffness), a luxuriant feel (dispersibility of fiber bundles), and a slick feel (resin clusters of appropriate size) and can be used suitably as a seat cover material or interior design material for interiors, cars, airplanes, railway cars, etc. and garment accessory products. This artificial leather comprises a fiber sheet and a polyurethane resin and is characterized in that: the fiber sheet comprises at least a fiber layer (A) that forms a first outer surface of the artificial leather; the k-nearest neighbor distance proportion (k=9, radius r=20 μm) between cross-sections of single fibers configuring the fiber layer (A) in a thickness direction cross-section of the artificial leather is 10-80%; the cross-sectional polyurethane resin area ratio in a thickness direction cross-section of the fiber layer (A) is 10-30%; and the standard deviation of the cross-sectional polyurethane resin area ratio in a thickness direction cross-section of the fiber layer (A) is 25% or less.

1 . Artificial leather comprising a fiber sheet and a polyurethane resin, wherein the fiber sheet contains at least a fiber layer (A) constituting the first outer surface of the artificial leather, the k-nearest neighbor distance ratio (k=9, radius r=20 μm) between cross-sections of the single fibers forming the fiber layer (A) in a cross-section of the artificial leather in the thickness direction is 10% to 80%, the cross-sectional polyurethane resin area ratio in a cross-section of the fiber layer (A) in the thickness direction is 10% to 30%, and the standard deviation for the cross-sectional polyurethane resin area ratio in a cross-section of the fiber layer (A) in the thickness direction is 25% or lower. 
     
     
         2 . The artificial leather according to  claim 1 , wherein in a three-dimensional image obtained by X-ray CT of the fiber layer (A), the average value of space sizes, as the diameters of maximum spheres that fit in the spaces excluding the fibers forming the fiber layer (A) and the polyurethane resin (average space size), is 5 μm to 35 μm in the thickness direction of the fiber layer (A). 
     
     
         3 . The artificial leather according to  claim 1 , wherein the fiber sheet has a construction of two or more layers comprising a fiber layer (A) constituting the first outer surface, and a scrim and/or fiber layer (B) contacting the fiber layer (A). 
     
     
         4 . The artificial leather according to  claim 1 ,
 wherein the mean diameter of the single fibers composing the fiber layer (A) is 1.0 μm to 8.0 μm.   
     
     
         5 . The artificial leather according to  claim 1 ,
 wherein the polyurethane resin is a water-dispersed polyurethane resin.   
     
     
         6 . The artificial leather according to  claim 1 , wherein the adhesion rate of the polyurethane resin on the fiber sheet is 15 wt % to 50 wt %. 
     
     
         7 . The artificial leather according to  claim 1 , wherein the stiffness is 28 cm or lower. 
     
     
         8 . The artificial leather according to  claim 1 , wherein the fiber sheet is composed of polyester fibers. 
     
     
         9 . The artificial leather according to  claim 1 , wherein the luxuriant feel is grade 4.0 or higher. 
     
     
         10 . A method for producing the artificial leather according to  claim 1 , which comprises the following steps:
 a step of forming a fiber web of sea-island cut fibers, needle punching it, and then dissolving the sea-component of the fiber sheet, to obtain a fiber sheet with the island-component single fibers exposed; and   a step of subjecting the obtained fiber sheet to water flow dispersion treatment to obtain a fiber sheet with the single fibers dispersed.   
     
     
         11 . The method according to  claim 10 , which further comprises the following steps:
 a step of impregnating a water-dispersed polyurethane resin dispersion containing hot water-soluble resin microparticles into the fiber sheet with the single fibers dispersed, and then coagulating the polyurethane resin by heating to obtain a sheet filled with the polyurethane resin, and:   a step of using hot water to remove the hot water-soluble resin microparticles from the obtained sheet.   
     
     
         12 . The method according to  claim 10  or  11 , wherein the hot water-soluble resin microparticles are composed of a polyvinyl alcohol resin. 
     
     
         13 . The method according to  claim 10 , wherein the water flow dispersion treatment is carried out using a plurality of nozzles having nozzle hole intervals of 1.0 mm or smaller and nozzle hole diameters of 0.05 mm to 0.30 mm. 
     
     
         14 . The method according to  claim 10 , wherein the water flow dispersion treatment is carried out using a plurality of nozzles that discharge a water stream with a disturbance of 10% or greater. 
     
     
         15 . The method according to  claim 11 , wherein the solid concentration of the water-dispersed polyurethane resin dispersion is 10 wt % to 35 wt %. 
     
     
         16 . The method according to  claim 11 , wherein the content of hot water-soluble resin microparticles in the water-dispersed polyurethane resin dispersion is 1 wt % to 20 wt %.