Non-woven fabrics of wind-shrink fiber and laminate thereof

Abstract

The invention provides a nonwoven fabric of crimped conjugate fibers comprising (1) a first propylene-based polymer component and (2) a second propylene-based polymer component, and a laminate of the nonwoven fabric and other nonwoven fabrics or porous films, in which the melting point of the component (1) is higher by at least 20° C. than that of the component (2) a ratio of the two components in melt flow rate (component ( 2 )/component ( 1 )) is in the range of 0.8 to 1.2, and the component ratio expressed by (1)/(2) (by weight) is 50/50 to 5/95. The nonwoven fabric has an excellent bulkiness and softness, is excellent in terms of spinnability and fuzzing resistance, and can be spun by a conventional melt spinning. The laminate has further improved water impermeability and surface smoothness. The nonwoven fabric and the laminate using the same may both be used for disposable diapers or sanitary napkins.

What is claimed is:  
     
         1 . A nonwoven fabric of a crimped conjugate fiber comprising a first propylene-based polymer component and a second propylene-based polymer component, in which 
 said first and second propylene-based polymer components are arranged to have substantially different zones in the cross-section of the crimped conjugate fiber and are extended continuously along the longitudinal direction of the crimped conjugate fiber,    said second propylene-based polymer component forms at least a part of the peripheral surface continuously along the longitudinal direction of the crimped conjugate fiber,    the melting point of said first propylene-based polymer component is higher by at least 20° C. than the melting point of said second propylene-based polymer component as determined by a differential scanning calorimeter (DSC), and    the ratio of said first/second propylene-based polymer components (by weight) is in the range of 50/50 to 5/95.    
     
     
         2 . The nonwoven fabric composed of the crimped conjugate fiber according to  claim 1 , wherein the ratio of said second to first propylene-based polymer components in the melt flow rate (MFR: measurement temperature at 230° C. under a load of 2.16 kg), as determined in accordance with ASTM D1238, is in the range of 0.8 to 1.2 (the second component/the first component).  
     
     
         3 . The nonwoven fabric composed of the crimped conjugate fiber according to claims  1  or  2 , wherein the crimped conjugate fiber constituting the nonwoven fabric has at least two melting point peaks for the crimped conjugate fiber as determined by DSC on the first run, and the area for the lowest melting point peak is not smaller than the area for each of the other higher melting point peaks.  
     
     
         4 . The nonwoven fabric composed of the crimped conjugate fiber according to any one of  claims 1  to  3 , wherein the first or second propylene polymer is a propylene homopolymer or a propylene-ethylene random copolymer, having 0 to 10 mol % of the ethylene unit and MFR of 20 to 200 g/10 min.  
     
     
         5 . The nonwoven fabric composed of the crimped conjugate fiber according to any one of  claims 1  to  4 , wherein the crimped conjugate fiber is an eccentric core/sheath type conjugate fiber comprising the core composed of the first propylene-based polymer component and the sheath composed of the second propylene-based polymer component.  
     
     
         6 . The nonwoven fabric composed of the crimped conjugate fiber according to any one of  claims 1  to  4 , wherein the crimped conjugate fiber is a side-by-side type conjugate fiber comprising the first propylene-based polymer component and the second propylene-based polymer component.  
     
     
         7 . The nonwoven fabric composed of the crimped conjugate fiber according to any one of  claims 1  to  6 , wherein the nonwoven fabric is heat fused by an emboss processing.  
     
     
         8 . The nonwoven fabric composed of the crimped conjugate fiber according to  claim 7 , wherein said emboss processing is conducted under conditions of an emboss area percentage of 5 to 20% and a non-emboss unit area of at least 0.5 mm 2 .  
     
     
         9 . The nonwoven fabric composed of the crimped conjugate fiber according to any one of  claims 1  to  8 , wherein the nonwoven fabric of the crimped conjugate fiber is a spun-bonded nonwoven fabric produced by a spun-bonding process.  
     
     
         10 . A nonwoven fabric laminate comprising at least two-layer structure, at least one of which is the nonwoven fabric composed of the crimped conjugate fiber according to any one of  claims 1  to  9 .  
     
     
         11 . The nonwoven fabric laminate according to  claim 10 , wherein a plurality of the nonwoven fabrics composed of said crimped conjugate fiber different in the degree of crimps are laminated.  
     
     
         12 . The nonwoven fabric laminate according to  claim 10 , wherein at least one other layer constituting the laminate is a layer of a melt-blown nonwoven fabric produced by a melt-blowing process.  
     
     
         13 . The nonwoven fabric laminate according to  claim 10 , wherein at least one other layer constituting the laminate is a layer of a spun-bonded nonwoven fabric composed of microfibers produced by a spun-bonding process.  
     
     
         14 . The nonwoven fabric laminate according to  claim 10 , wherein at least one other layer constituting the laminate is an air permeable film layer.  
     
     
         15 . A disposable diaper using the nonwoven fabric of the crimped conjugate fiber or the nonwoven fabric laminate according to any one of claims  1  through  14 .  
     
     
         16 . A sanitary napkin using the nonwoven fabric of the crimped conjugate fiber or the nonwoven fabric laminate according to any one of claims  1  through  14 .