Nonwoven fabric and fiber product

Abstract

Provided is a spunbonded nonwoven fabric comprising a core-sheath composite fiber having a core part composed of a core component containing a propylene-based resin (A) satisfying the following (a) to (e) and a sheath part composed of a sheath component containing an ethylene-based resin. (a) [mmmm]=20 to 60 mol %, (b) [mm]×[rr]/[mr] 2 ≦2.0, (c) weight average molecular weight (Mw)=10,000 to 200,000, (d) molecular weight distribution (Mw/Mn)<4.0, and (e) a melting point (Tm-D), as defined as a peak top of a peak observed on the highest temperature side of a melting endothermic curve which is obtained by holding under a nitrogen atmosphere at −10° C. for 5 minutes and then increasing the temperature at a rate of 10° C./min with a differential scanning calorimeter (DSC), is from 0 to 120° C.

1 . A spunbonded nonwoven fabric comprising a core-sheath composite fiber having a core part composed of a core component containing a propylene-based resin (A) satisfying the following (a) to (e) and a sheath part composed of a sheath component containing an ethylene-based resin:
 (a) [mmmm]=20 to 60 mol,   (b) [mm]×[rr]/[mr] 2 ≦2.0,   (c) weight average molecular weight (Mw)=10,000 to 200,000,   (d) molecular weight distribution (Mw/Mn)<4.0, and   (e) a melting point (Tm-D), as defined as a peak top of a peak observed on the highest temperature side of a melting endothermic curve which is obtained by holding under a nitrogen atmosphere at −10° C. for 5 minutes and then increasing the temperature at a rate of 10° C./min with a differential scanning calorimeter (DSC), is from 0 to 120° C.   
     
     
         2 . The spunbonded nonwoven fabric according to  claim 1 , wherein a content of the propylene-based resin (A) in the core component is 1 to 50% by mass. 
     
     
         3 . The spunbonded nonwoven fabric according to  claim 1 , wherein the core component further contains a propylene-based resin (B) in which a melting point (Tm-D), as defined as a peak top of a peak observed on the highest temperature side of a melting endothermic curve which is obtained by holding under a nitrogen atmosphere at −10° C. for 5 minutes and then increasing the temperature at a rate of 10° C./min with a differential scanning calorimeter (DSC), is higher than 120° C. 
     
     
         4 . The spunbonded nonwoven fabric according to  claim 3 , wherein a content of the propylene-based resin (B) in the core component is 50 to 99% by mass. 
     
     
         5 . The spunbonded nonwoven fabric according to  claim 1 , wherein a content of the ethylene-based resin in the sheath component is 50 to 100% by mass. 
     
     
         6 . The spunbonded nonwoven fabric according to  claim 1 , wherein the propylene-based resin (A) satisfies the following (f) and (g):
 (f) rrrr/(1−mmmm)≦0.1, and   (g) [rmrm]>2.5 mol %.   
     
     
         7 . The spunbonded nonwoven fabric according to  claim 1 , wherein a total content of the propylene-based resin (A) in the core-sheath composite fiber as calculated according to the following expression is 0.5 to 47.5% by mass:
   [Total content of propylene-based resin ( A )]= Wc×Xc/ 100   Wc: Mass fraction of the core part   Xc: Mass fraction of the propylene-based resin (A) in the core component constituting the core part.   
     
     
         8 . The spunbonded nonwoven fabric according to  claim 1 , wherein the propylene-based resin (A) is a propylene homopolymer or a copolymer in which a copolymerization ratio of a propylene unit is 90 mol % or more. 
     
     
         9 . The spunbonded nonwoven fabric according to  claim 3 , wherein the propylene-based resin (B) is a propylene homopolymer or a copolymer in which a copolymerization ratio of a propylene unit is 50 mol % or more. 
     
     
         10 . The spunbonded nonwoven fabric according to  claim 1 , wherein the ethylene-based resin is an ethylene homopolymer or a copolymer in which a copolymerization ratio of an ethylene unit is more than 50 mol %. 
     
     
         11 . A multilayered nonwoven fabric comprising a laminate of at least two or more layers of nonwoven fabric, at least one layer of the nonwoven fabric constituting an outer layer of the multilayered nonwoven fabric being composed of the spunbonded nonwoven fabric according to  claim 1 . 
     
     
         12 . A fiber product using the spunbonded nonwoven fabric according to  claim 1 . 
     
     
         13 . A fiber product using the multilayered nonwoven fabric according to  claim 11 . 
     
     
         14 . The spunbonded nonwoven fabric according to  claim 2 , wherein the core component further contains a propylene-based resin (B) in which a melting point (Tm-D), as defined as a peak top of a peak observed on the highest temperature side of a melting endothermic curve which is obtained by holding under a nitrogen atmosphere at −10° C. for 5 minutes and then increasing the temperature at a rate of 10° C./min with a differential scanning calorimeter (DSC), is higher than 120° C. 
     
     
         15 . The spunbonded nonwoven fabric according to  claim 2 , wherein a total content of the propylene-based resin (A) in the core-sheath composite fiber as calculated according to the following expression is 0.5 to 47.5% by mass:
   [Total content of propylene-based resin ( A )]= Wc×Xc/ 100   Wc: Mass fraction of the core part   Xc: Mass fraction of the propylene-based resin (A) in the core component constituting the core part.   
     
     
         16 . The spunbonded nonwoven fabric according to  claim 3 , wherein a total content of the propylene-based resin (A) in the core-sheath composite fiber as calculated according to the following expression is 0.5 to 47.5% by mass:
   [Total content of propylene-based resin ( A )]= Wc×Xc/ 100   Wc: Mass fraction of the core part   Xc: Mass fraction of the propylene-based resin (A) in the core component constituting the core part.   
     
     
         17 . The spunbonded nonwoven fabric according to  claim 4 , wherein a total content of the propylene-based resin (A) in the core-sheath composite fiber as calculated according to the following expression is 0.5 to 47.5% by mass:
   [Total content of propylene-based resin ( A )]= Wc×Xc/ 100   Wc: Mass fraction of the core part   Xc: Mass fraction of the propylene-based resin (A) in the core component constituting the core part.   
     
     
         18 . The spunbonded nonwoven fabric according to  claim 5 , wherein a total content of the propylene-based resin (A) in the core-sheath composite fiber as calculated according to the following expression is 0.5 to 47.5% by mass:
   [Total content of propylene-based resin ( A )]= Wc×Xc/ 100   Wc: Mass fraction of the core part   Xc: Mass fraction of the propylene-based resin (A) in the core component constituting the core part.   
     
     
         19 . The spunbonded nonwoven fabric according to  claim 6 , wherein a total content of the propylene-based resin (A) in the core-sheath composite fiber as calculated according to the following expression is 0.5 to 47.5% by mass:
   [Total content of propylene-based resin ( A )]= Wc×Xc/ 100   Wc: Mass fraction of the core part   Xc: Mass fraction of the propylene-based resin (A) in the core component constituting the core part.