Absorbent, nonwoven material exhibiting z-direction density gradient

Abstract

The present material contains density gradients which direct fluid into the material and distribute it providing more effective fluid transport and efficient utilization of storage capacity. The material consists of two regions. In the first region, the material has a low-density stratum adjacent to one surface, overlaying at least one higher density stratum adjacent to the opposite surface of the sheet. These strata create a density gradient in the thickness direction (Z-direction) of the sheet. The second region consists of a fluid distribution structure that has a higher density than at least the lower density of the strata comprising the first region. The fluid distribution structure is in direct fluid communication with the adjacent strata in the first region, along their boundaries.

1 - 12 . (canceled) 
     
     
         13 . A method making an absorbent, nonwoven material exhibiting a Z-direction density gradient, comprising the steps of:
 providing a cellulosic tissue layer;   depositing cellulosic material on said tissue layer;   compacting said cellulosic material to form a fibrous matrix of a first, relatively low-density stratum;   providing a second, relatively high-density stratum with hydrogen bonding formed by applying heat and pressure providing a stable density, comprising another fibrous matrix, on said first stratum; and   compacting said first and second strata by applying heat and pressure in a defined pattern, to form an absorbent material with a Z-direction density gradient, including forming a liquid-distribution network extending through the entire thickness of the material, and laterally adjacent to at least one portion of said low-density and high-density strata, wherein said cellulosic tissue layer is bonded to said liquid-distribution network for integrating said absorbent material against delamination, and for inhibiting release of the fibrous material of said first, low-density stratum.   
     
     
         14 . A method making an absorbent, nonwoven material in accordance with claim  12 , including
 forming said liquid-distribution network with at least one longitudinally extending densified region.   
     
     
         15 . A method making an absorbent, nonwoven material in accordance with claim  12 , including
 forming said liquid-distribution network to comprise a land-and-sea densified region.   
     
     
         16 . A method making an absorbent, nonwoven material in accordance with claim  12 , including
 forming at least one of said fibrous matrices as a blend of cellulosic fibrous material and superabsorbent polymeric material.   
     
     
         17 . A method making an absorbent, nonwoven material in accordance with claim  12 , wherein
 said step of providing said high-density stratum includes forming and compacting said high-density stratum separately from said low-density stratum, and thereafter positioning said high-density stratum on said low density stratum.   
     
     
         18 . A method of making an absorbent, nonwoven material in accordance with  claim 17 , using an airlaid formation apparatus, comprising a single formation section, and a single bonding calender or multiple bonding calenders.