Absorbent article comprising a primary aqueous-liquid-absorbing agent

Abstract

An absorbent article comprising an absorbent core, which comprises at least one region comprising an aqueous-liquid-absorbing agent that contains water-absorbent resin particles, wherein the water-absorbent resin particles are obtained by a process including the step of polymerizing a water-soluble ethylenically unsaturated monomer having a carboxyl group, in the presence of an internal-crosslinking agent having at least four functional groups each capable of forming a covalent bond with a carboxyl group to thereby obtain a hydropolymer that is internally cross-linked and surface-crosslinked, the aqueous-liquid-absorbing agent being characterized by exhibiting a water absorption capacity (CRC) of 5 to 25 g/g and a saline flow conductivity (SFC) of not less than 1216 cm3·s·10-7/g.

1 . An absorbent article comprising an absorbent core, which includes a primary aqueous-liquid-absorbing agent that contains water-absorbent resin particles, the water-absorbent resin particles, comprising polymerized water-soluble ethylenically unsaturated monomers having a carboxyl group, said resin particles being internally cross-linked and surface-crosslinked,
 wherein the primary aqueous-liquid-absorbing agent exhibits a water absorption capacity (CRC) of 5 to 25 g/g and a saline flow conductivity (SFC) of not less than 1216×10 −7  cm 3  s/g.   
     
     
         2 . An absorbent article comprising a primary aqueous-liquid-absorbing agent exhibiting a water absorption capacity (CRC) of 5 to 25 g/g and a saline flow conductivity (SFC) of not less than 1216×10 −7  cm 3  s/g, obtained by:
 (a) polymerizing a water-soluble ethylenically unsaturated monomer having a carboxyl group in an aqueous monomer solution including the water-soluble ethylenically unsaturated monomer having a carboxyl group, in the presence of an internal-crosslinking agent having at least four functional groups each capable of forming a covalent bond with a carboxyl group to thereby obtain a hydropolymer;   (b) drying the hydropolymer obtained in the step (a) at a temperature of not less than 150° C. to thereby obtain water-absorbent resin particles; and   (c) surface-crosslinking the water-absorbent resin particles obtained in the step (b), wherein the amount (Y) (mol %) of the internal-crosslinking agent as used, relative to the water-soluble ethylenically unsaturated monomer having a carboxyl group, is expressed by the following equation (1):
     Y≧− 0.06/{2−(2.35 X/ 100)}  (1) 
   where X is neutralization degree (mol %) of a carboxyl group in the water-absorbent resin particles and is in the range of 45 to 85 mol %.   
     
     
         3 . The absorbent article of  claim 1 , wherein the absorption rate (modified FSR) of the primary aqueous-liquid-absorbing agent is not less than 0.1 g/g/s. 
     
     
         4 . The absorbent article of  claim 2 , wherein the primary aqueous-liquid-absorbing agent has a wet porosity of not less than 20%. 
     
     
         5 . The absorbent article of  claim 1 , wherein the water-absorbing resin particles comprise agglomerated particles and the primary aqueous-liquid-absorbing agent is particulate, having at least 90 weight % by weight of particles with a particle diameters in the range of 150 to 850 μm. 
     
     
         6 . The absorbent article of  claim 2 , wherein said primary aqueous-liquid-absorbing agent further comprises a liquid-permeability-enhancing agent, selected from water-soluble metal compounds and water-soluble polycationic compounds. 
     
     
         7 . The absorbent article of  claim 1 , wherein said water-absorbing resin particles are internally crosslinked with an internal-crosslinking agent having at least four functional groups each capable of forming a covalent bond with the carboxyl group. 
     
     
         8 . The absorbent article of  claim 1 , further comprising a secondary aqueous-liquid-absorbing agent, comprising water-absorbing resin particles, having a SFC of less than 600×10 −7  cm 3  s/g, preferably a SFC of between 40×10 −7  cm 3  s/g and 400×10 −7  cm 3  s/g. 
     
     
         9 . The absorbent article of  claim 8 , wherein the absorbent core further comprises an acquisition/storage layer and a storage layer, whereby said primary aqueous-liquid-absorbing agent is comprised in at least part of said acquisition/storage layer and whereby said secondary aqueous-liquid-absorbing agent is comprised in at least part of said storage region. 
     
     
         10 . The absorbent article of  claim 1 , wherein the absorbent core includes a layer comprising said primary aqueous-liquid-absorbing agent and less than 10% by weight of said agent of a fibrous cellulose material. 
     
     
         11 . The absorbent article of  claim 1 , having a maximum dry caliper in the crotch region of 4.5 mm or less. 
     
     
         12 . The absorbent article of  claim 1 , wherein the absorbent core comprises at least said primary aqueous-liquid-absorbing agent and optionally said secondary aqueous-liquid-absorbing agent, and said core having one or more regions with an average density greater than about 0.2 g/cm 3 . 
     
     
         13 . The absorbent article of  claim 2 , further comprising a secondary aqueous-liquid-absorbing agent, comprising water-absorbing resin particles, having a SFC of less than 600×10 −7  cm 3  s/g, preferably a SFC of between 40×10 −7  cm 3  s/g and 400×10 −7  cm 3  s/g. 
     
     
         14 . The absorbent article of  claim 2 , wherein the absorbent core includes a layer comprising said primary aqueous-liquid-absorbing agent and less than 10% by weight of said agent of a fibrous cellulose material. 
     
     
         15 . The absorbent article of  claim 2 , having a maximum dry caliper in the crotch region of 4.5 mm or less. 
     
     
         16 . The absorbent article of  claim 2 , wherein the absorbent core comprises at least said primary aqueous-liquid-absorbing agent and optionally said secondary aqueous-liquid-absorbing agent, and said core having one or more regions with an average density greater than about 0.2 g/cm 3