Sheet of non-woven fabric and production process of same

Abstract

A sheet of nonwoven fabric which has surface irregularities, the shape of the surface irregularities being less apt to be changed by external pressure, etc. The sheet has a machine, cross and thickness which are perpendicular to one another. The upper surface has a plurality of protrusions continuously extending, in parallel, in the cross direction and further has a plurality of recesses ( 3 ) that are located between the adjacent protrusions and extend in the cross direction. The sheet includes first and second fibrous layers located on the upper-surface side and the lower-surface side, respectively. The first fibrous layer comprises heat-fusible fibers, and the second fibrous layer comprises coil-shaped three-dimensional crimp fibers that are oriented mainly in the machine direction and form a network by entanglement thereof without having been fused at the sites where the crimp fibers cross one another.

1 . A non-woven fabric sheet having a mutually perpendicular machine direction MD, cross-machine direction CD and thickness direction TD, an upper surface and a lower surface in the thickness direction TD, a plurality of protrusions continuously extending in parallel in the cross-machine direction CD formed in the upper surface, and a plurality of recesses extending in the cross-machine direction CD between adjacent protrusions formed in the upper surface; wherein,
 the non-woven fabric sheet is composed of a first fibrous layer on an upper surface side and a second fibrous layer on a lower surface side, the first fibrous layer contains heat-fusible fibers and the second fibrous layer contains coiled, three-dimensional crimped fibers; and   the coiled, three-dimensional crimped fibers of the second fibrous layer are mainly oriented in the machine direction MD, and form a network as a result of entanglement thereof without being fused at those sites where the crimped fibers mutually intersect.   
     
     
         2 . The non-woven fabric sheet according to  claim 1 , wherein the heat-fusible fibers of the first fibrous layer are mainly oriented in the machine direction, and are fused at those sites where they mutually intersect. 
     
     
         3 . The non-woven fabric sheet according to  claim 1 , wherein through holes are present at fixed intervals in the recesses, and the recesses are stretched preferentially to the protrusions when the non-woven fabric sheet is stretched in the machine direction. 
     
     
         4 . The non-woven fabric sheet according to  claim 1 , wherein a plurality of grooves continuously extending in parallel in the machine direction are formed in the lower surface of the non-woven fabric sheet, and the through holes are present in the grooves. 
     
     
         5 . A production process of a non-woven fabric sheet, comprising:
 a) a step for opening a fiber assembly containing heat-fusible fibers by passing through a carding machine to form a web containing heat-fusible fibers,   b) a step for opening a fiber assembly containing latent crimpable fibers by passing through a carding machine to form a web containing latent crimp able fibers,   c) a step for superimposing the web containing heat-fusible fibers and the web containing latent crimpable fibers to form a laminated web,   d) a step for generating a difference in shrinkage force in the machine direction in the laminated web by expressing crimping of the latent crimpable fibers during a heat treatment step over a prescribed width in the machine direction,   f) a heat treatment step for heating the web to a temperature that is lower than the fusing temperature of the heat-fusible fibers but causes expression of crimping by the latent crimpable fibers using means for lowering resistance to expression of crimping by the latent crimpable fibers, and   g) a step for fusing the web obtained in step f at sites where the heat-fusible fibers mutually intersect by heating to a temperature equal to or higher than the fusing temperature of the heat-fusible fibers.   
     
     
         6 . The process according to  claim 5 , wherein step d is a step in which the laminated web is transported by placing on a support, in which liquid passage portions and protruding liquid blocking portions extending in parallel in the cross-machine direction CO alternately repeat in the machine direction MD, while reorienting the fibers by spraying a liquid from a plurality of nozzles arranged in the cross-machine direction. 
     
     
         7 . The process according to  claim 5 , wherein the means for lowering resistance to expression of crimping by the latent crimpable fibers is a method for transporting at a lower transport speed than that of previous step. 
     
     
         8 . The process according to  claim 5 , wherein the means for lowering resistance to expression of crimping by the latent crimpable fibers is a floating dryer. 
     
     
         9 . The process according to  claim 5 , comprising:
 e) a step for transporting the web obtained in step d to step f between step d and step f.   
     
     
         10 . The process according to  claim 5 , comprising:
 h) a step for cooling the web obtained in step  9  after step g.   
     
     
         11 . An absorbent article in which the non-woven fabric sheet according to  claim 1  is provided as a surface sheet or absorbent body.