Nonwoven fabric

Abstract

Short fibers of thermoplastic synthetic resin are fusion bonded to one another to form a nonwoven fabric. The nonwoven fabric is formed on its upper surface with crests and troughs extending in parallel to one another. The crests include first crests having a uniform height dimension from a lower surface of the nonwoven fabric and second crests having a uniform height dimension from a lower surface of the nonwoven fabric which is smaller than the height dimension of the first crests. Density of the nonwoven fabric gradually increases in the order of the first crests, the second crests and the troughs. The first crests are formed so that the density of the first crests remains lower than the density of the second crests even when the first crests are compressed toward the lower surface until the first crests becomes flush with the level of the second crests.

1 . A nonwoven fabric formed of short fibers of thermoplastic synthetic resin fusion bonded to one another and having a length direction, a width direction and a thickness direction extending orthogonally to one another, including an upper surface and a lower surface opposed to the upper surface as viewed in the thickness direction wherein
 the upper surface is formed with crests and troughs undulating in the width direction and extending in parallel to one another in the length direction and   the crests comprise first crests having a uniform height dimension and second crests having a uniform height dimension measured from the lower surface wherein the height dimension of the first crests is larger than the height dimension of the second crests, wherein:   density of the nonwoven fabric gradually increases in order of the first crests, the second crests and the troughs and the density of the first crests remains lower than the density of the second crests even when the first crests are compressed from the upper surface toward the lower surface until the first crests become flush with the second crests.   
     
     
         2 . The nonwoven fabric defined by  claim 1 , wherein the nonwoven fabric has a basis mass in a range of 18 to 100 g/m 2  and each of the short fibers has a fineness in a range of 1 to 8 dtex and a fiber length in a range of 20 to 80 mm, and wherein the nonwoven fabric has been modified to become hydrophilic. 
     
     
         3 . The nonwoven fabric defined by  claim 1 , wherein the short fibers are conjugate fibers comprising two types of the thermoplastic synthetic resin having different fusion temperatures and these two types of the thermoplastic synthetic resin are fusion bonded to each other via one of the thermoplastic synthetic resins having a lower fusion temperature. 
     
     
         4 . The nonwoven fabric defined by  claim 1 , wherein the height dimension of the first crests is in a range of 1 to 5 mm and the height dimension of the second crests is lower than the height dimension of the first crests by a range of 0.5 to 2 mm. 
     
     
         5 . The nonwoven fabric defined by  claim 1 , wherein the first crests and the second crests are formed alternately in the width direction and each of the troughs is interposed between each pair of the adjacent the first crest and the second crest.