Crosslinked cellulosic product formed by extrusion process

Abstract

The present invention provides an extruded cellulosic fibrous product. In one embodiment, the product includes in situ crosslinked cellulosic fibers. In another embodiment, the product further includes a bonding agent. The product can optionally include other fibers and absorbent material. Methods for making the cellulosic fibrous product and absorbent articles that include the cellulosic fibrous product are also described.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:  
     
         1 . A method for making a cellulosic fibrous composite, comprising: 
 (a) combining cellulosic fibers with a surfactant in a mixing device;    (b) generating a foam comprising the cellulosic fibers, surfactant, and air in the device; and    (c) extruding the foam from the device to provide a cellulosic fibrous composite.    
     
     
         2 . The method of  claim 1 , wherein the cellulosic fibers combined with the surfactant have a solids content greater than about 15 percent.  
     
     
         3 . The method of  claim 1 , wherein the cellulosic fibers combined with the surfactant have a solids content less than about 50 percent.  
     
     
         4 . The method of  claim 1 , wherein the mixing device comprises a plate mixer extrusion device.  
     
     
         5 . The method of  claim 1 , wherein the mixing device comprises a twin-screw extrusion device.  
     
     
         6 . The method of  claim 1 , wherein the foam has an air content greater than about 75 percent by volume based on the volume of the foam.  
     
     
         7 . The method of  claim 1 , wherein the foam has an air content greater than about 90 percent by volume based on the volume of the foam.  
     
     
         8 . The method of  claim 1 , wherein the foam has an air content greater than about 98 percent by volume based on the volume of the foam.  
     
     
         9 . The method of  claim 1 , wherein the foam has a density of greater than about about 20 g/L.  
     
     
         10 . The method of  claim 1 , wherein the foam has a density of less than about about 100 g/L.  
     
     
         11 . The method of  claim 1 , wherein the surfactant is present in an amount from about 0.01 to about 5 percent by weight based on the weight of the composite.  
     
     
         12 . The method of  claim 1  further comprising drying the extruded cellulosic fibrous composite.  
     
     
         13 . The method of  claim 1 , wherein the foam further comprises a crosslinking agent.  
     
     
         14 . The method of  claim 13  further comprising heating the extruded composite to provide a bonded composite.  
     
     
         15 . The method of  claim 1 , wherein the foam further comprises a latex.  
     
     
         16 . The method of  claim 15  further comprising heating the extruded composite to provide a bonded composite.  
     
     
         17 . The method of  claim 1 , wherein the foam further comprises thermoplastic fibers.  
     
     
         18 . The method of  claim 17  further comprising heating the extruded composite to provide a bonded composite.  
     
     
         19 . The method of  claim 1 , wherein the cellulosic fibers comprise cellulosic fibers treated with a crosslinking agent.  
     
     
         20 . The method of  claim 19  further comprising heating the extruded composite to provide a bonded composite.  
     
     
         21 . The method of  claim 1 , wherein the foam further comprises a wet strength agent.  
     
     
         22 . The method of  claim 21  further comprising heating the extruded composite to provide a bonded composite.  
     
     
         23 . The method of  claim 1 , wherein the cellulosic fibers comprise crosslinked cellulosic fibers.  
     
     
         24 . The method of  claim 1 , wherein the foam further comprises absorbent material.  
     
     
         25 . A cellulosic fibrous composite, comprising bonded crosslinked cellulosic fibers, the composite having a mid-point desorption pressure less than about 14 cm H 2 O.  
     
     
         26 . The composite of  claim 25  having a mid-point desorption pressure less than about 12 cm H 2 O.  
     
     
         27 . The composite of  claim 25  having a mid-point desorption pressure less than about 10 cm H 2 O.  
     
     
         28 . The composite of  claim 25  having a density less than about 0.10 g/cm 3 .  
     
     
         29 . The composite of  claim 25  having a density greater than about 0.02 g/cm 3 .  
     
     
         30 . The composite of  claim 25  having a fourth gush liquid acquisition rate greater than about 0.4 mL/sec.  
     
     
         31 . The composite of  claim 25 , wherein the crosslinked cellulosic fibers comprise polyacrylic acid crosslinked fibers.  
     
     
         32 . The composite of  claim 25 , wherein the crosslinked cellulosic fibers comprise cellulosic fibers crosslinked with a blend of citric acid and polyacrylic acid.  
     
     
         33 . The composite of  claim 25 , wherein the crosslinked cellulosic fibers comprise cellulosic fibers pretreated with a crosslinking agent and cured during composite formation.  
     
     
         34 . The composite of  claim 25 , wherein the crosslinked cellulosic fibers comprise cellulosic fibers treated with a crosslinking agent during composite formation.  
     
     
         35 . The composite of  claim 25 , wherein the crosslinked cellulosic fibers comprise intrafiber crosslinked cellulosic fibers and interfiber crosslinked cellulosic fibers.  
     
     
         36 . The composite of  claim 25  further comprising thermoplastic fibers.  
     
     
         37 . The composite of  claim 36 , wherein the thermoplastic fibers comprise bicomponent fibers.  
     
     
         38 . The composite of  claim 25  further comprising a latex.  
     
     
         39 . The composite of  claim 25  further comprising a wet strength agent.  
     
     
         40 . The composite of  claim 25  further comprising absorbent material.  
     
     
         41 . A foam, comprising a cellulosic fibers, a surfactant, and air, wherein the foam has an air content greater than about 75 percent by volume.