High-Performance Absorbent Structure

Abstract

Disclosed is an absorbent structure having wet integrity greater than about 4.0 mN/gsm, softness greater than 8.0/J, pliability greater than about 70/N, and providing a substantially dry liquid-accepting surface after receiving a quantity of liquid. The structure includes an upper ply having an upper fluid receiving surface and a lower surface and including (i) a top stratum including synthetic matrix fibers bonded with a binder, the matrix fibers having length from about 2 to about 15 mm; (ii) a middle stratum in fluid communication with the top stratum, the middle stratum including natural fibers, superabsorbent particles and a binder; and (iii) a bottom stratum in fluid communication with the middle stratum, the bottom stratum including natural fibers and a binder. The structure also includes a lower ply in fluid communication with the upper ply, the lower ply having an upper surface and a lower surface and including at least one stratum including natural fibers, superabsorbent polymer particles, and a binder, wherein the lower surface of the upper ply has a surface area less than about 80% of the upper surface area of the lower ply.

1 . A method of manufacturing an absorbent structure comprising: 
 (a) providing an upper ply having an upper fluid receiving surface and a lower surface and comprising: 
 i) a top stratum comprising synthetic matrix fibers bonded with a binder, the matrix fibers having length from about 2 to about 15 mm;  
 ii) a middle stratum in fluid communication with the top stratum, the middle stratum including natural fibers, superabsorbent particles and a binder; and  
 iii) bottom stratum in fluid communication with the middle stratum, the bottom stratum including natural fibers and a binder; and  
   (b) providing a lower ply in fluid communication with the upper ply, the lower ply having an upper surface and a lower surface, where at least one stratum includes natural fibers, superabsorbent polymer particles, and a binder,    wherein the lower surface of the upper ply has a surface area less than about 80% of the upper surface area of the lower ply, and wherein the structure has a wet integrity greater than about 4.0 mN/gsm, softness greater than 8.0/J, pliability greater than about 70/N, and providing a substantially dry liquid-accepting surface after receiving a quantity of liquid.    
     
     
         2 . The method of  claim 1 , wherein each ply is made by an airlaid process.  
     
     
         3 . The method of  claim 2 , wherein the airlaid process is a unitary process comprising: 
 a) feeding raw materials into one or more forming heads to form a sheet layer;    b) laying the sheet layer on a carrier;    c) curing with minimum pressure; and optionally    d) calendaring the sheet layer.    
     
     
         4 . A method of manufacturing an absorbent structure comprising: 
 (a) providing an upper ply having an upper fluid receiving surface and a lower surface comprising: 
 i) a top stratum including synthetic matrix fibers bonded with a binder, the matrix fibers having length of from about 2 to about 15 mm;  
 ii) a middle stratum in fluid communication with the top stratum, the middle stratum including natural fibers and superabsorbent polymer particles; and  
 iii) a bottom stratum in fluid communication with the middle stratum, including natural fibers and a binder; and  
   (b) providing a lower ply in fluid communication with the upper ply, the lower ply having an upper surface and a lower surface, where: 
 i) the top stratum includes natural fibers and a binder; and  
 ii) the bottom stratum includes natural fibers, superabsorbent polymer particles, and a binder,  
   wherein:    a) the lower surface of the upper ply has a surface area less than about 80% of the upper surface area of the lower ply;    b) the top stratum of the upper ply exhibits essentially no fluid wicking capability;    c) the basis weight of the top stratum of the upper ply is from about 20 gsm to about 120 gsm;    d) the binder content (per cent by weight) of the top stratum of the upper ply is from about 5% to about 20%;    e) the basis weight of the middle stratum of the upper ply is from about 50 gsm to about 1000 gsm;    f) the binder content (per cent by weight) of the middle stratum of the upper ply is from about 1% to about 10%;    g) the basis weight of the bottom stratum of the upper ply is from about 10 gsm to about 150 gsm;    h) the binder content (per cent by weight) of the bottom stratum of the upper ply is from about 5% to about 15%;    i) the content of superabsorbent particles in the upper ply is lower than the content of superabsorbent particles in the lower ply;    j) the lower ply contains at least 30% superabsorbent particles based on the total basis weight of the lower ply;    k) the top stratum of the lower ply contains from about 0% to about 20% superabsorbent particles based on the basis weight of the top stratum of the lower ply;    l) the basis weight of the lower ply is from about 100 gsm to about 1000 gsm;    m) the apparent density of the lower ply is about 0.15 g/cc to about 0.25 g/cc;    n) the apparent density of the upper ply is lower than the apparent density of the lower ply;    o) the binder content (per cent by weight) of the lower ply is from about 1% to about 8%; and    p) the structure has a wet integrity greater than about 4.0 mN/gsm, softness greater than 8.0/J, pliability greater than about 70/N, and providing a substantially dry liquid-accepting surface after receiving a quantity of liquid.    
     
     
         5 . A method of manufacturing an absorbent structure comprising: 
 a) providing an upper ply including: 
 i) a top stratum including polyester matrix fibers bonded with latex in an amount of 15 to 25% by weight of the top stratum, the matrix fibers having length from about 4 mm to about 8 mm and having thickness from about 9 to about 15 denier per fiber, the basis weight of the top stratum being from about 40 to about 60 gsm;  
 ii) a middle stratum in fluid communication with the top stratum, the middle stratum including softwood fluff, superabsorbent polymer particles, and binder fiber, the content of the superabsorbent polymer particles being from about 30 to 40% of the basis weight of the middle stratum, the content of the binder fibers being from about 6 to about 12% of the basis weight of the middle stratum, and the basis weight of the middle stratum being from about 150 to about 200 gsm;  
 iii) a bottom stratum in fluid communication with the middle stratum, including softwood fluff and binder fibers, the content of the binder fibers being from about 8 to about 16% of the basis weight of the bottom stratum, and the basis weight of the bottom stratum being from about 60 to about 120 gsm; and  
   b) providing a lower ply in fluid communication with the upper ply, the lower ply comprising: 
 i) a top stratum including softwood fluff and binder fibers, the content of the binder fibers being from about 10 to about 25% of the basis weight of the top stratum, and basis weight being from about 20 to about 60 gsm;  
 ii) a bottom stratum including softwood fluff, superabsorbent polymer particles, and binder fibers, the content of the superabsorbent polymer particles being from about 50 to about 80% of the basis weight of the bottom stratum, the content of the binder fibers being from about 2 to 5% of the basis weight of the bottom stratum; and  
 iii) cellulose tissue upon which the lower ply has been formed,  
 wherein:  
   a) the upper ply is airlaid and has a surface area adjacent to the lower ply, the surface area being from about 40 to 60% of the facing surface area of the lower ply;    b) the density of the upper ply is from about 0.05 to about 1.0 g/cc; and    c) the density of the lower ply is from about 0.15 to about 0.3 g/cc.    
     
     
         6 . A method of manufacturing an absorbent structure comprising: 
 a) providing an upper ply containing: 
 i) a top stratum including polyester matrix fibers bonded with latex in an amount of 15 to 25% by weight of the top stratum, the matrix fibers having length from about 4 mm to about 8 mm and having thickness from about 9 to about 15 denier per fiber, the basis weight of the top stratum being from about 40 to about 60 gsm;  
 ii) a middle stratum in fluid communication with the top stratum, the middle stratum including softwood fluff, superabsorbent polymer particles, and binder fiber, the content of the superabsorbent polymer particles being from about 40 to 60% of the basis weight of the middle stratum, the content of the binder fibers being from about 6 to about 12% of the basis weight of the middle stratum, and the basis weight of the middle stratum being from about 200 to about 280 gsm;  
 iii) a bottom stratum in fluid communication with the middle stratum, including softwood fluff and binder fibers, the content of the binder fibers being from about 8 to about 16% of the basis weight of the bottom stratum, and the basis weight of the bottom stratum being from about 60 to about 120 gsm; and  
   b) providing a lower ply in fluid communication with the upper ply, the lower ply comprising: 
 i) a top stratum including softwood fluff and binder fibers, the content of the binder fibers being from about 10 to about 25% of the basis weight of the top stratum, and basis weight being from about 20 to about 60 gsm;  
 ii) a bottom stratum including softwood fluff, superabsorbent polymer particles, and binder fibers, the content of the superabsorbent polymer particles being from about 40 to about 60% of the basis weight of the bottom stratum, the content of the binder fibers being from about 2 to 5% of the basis weight of the bottom stratum, and the basis weight of the bottom stratum being from about 200 to about 350 gsm; and  
 iii) cellulose tissue upon which the lower ply has been formed,  
 wherein:  
   c) the upper ply is airlaid and has a surface area adjacent to the lower ply, the surface area being from about 40 to 60% of the facing surface area of the lower ply;    d) the density of the upper ply is from about 0.05 to about 1.0 g/cc; and    e) the density of the lower ply is from about 0.15 to about 0.3 g/cc.    
     
     
         7 . A method of manufacturing an absorbent structure comprising: 
 a) providing an upper ply having an upper fluid receiving surface and a lower surface and comprising: 
 i) a top stratum comprising synthetic matrix fibers bonded with a binder, the matrix fibers having length from about 2 to about 15 mm;  
 ii) a middle stratum in fluid communication with the top stratum, the middle stratum including natural fibers, superabsorbent particles and a binder; and  
 iii) a bottom stratum in fluid communication with the middle stratum, the bottom stratum including natural fibers and a binder; and  
   b) providing a lower ply in fluid communication with the upper ply, the lower ply having an upper surface and a lower surface, where at least one stratum including natural fibers, superabsorbent polymer particles, and a binder, wherein the lower surface of the upper ply has a surface area less than about 80% of the upper surface area of the lower ply;    c) the basis weight of the top stratum of the upper ply is from about 20 gsm to about 120 gsm;    d) the binder content (per cent by weight) in the top stratum of the upper ply is from about 5% to about 20%;    e) the basis weight of the middle stratum of the upper ply is from about 50 gsm to about 1000 gsm;    f) the binder content (per cent by weight) in the middle stratum of the upper ply is from about 1% to about 10%;    g) the basis weight of the bottom stratum of the upper ply is from about 10 gsm to about 150 gsm;    h) the binder content (per cent by weight) in the bottom stratum of the upper ply is from about 5% to about 15%;    i) the superabsorbent particle content (per cent by weight) in the upper ply is lower than the content of superabsorbent particles in the lower ply;    j) apparent density of the upper ply is lower than the apparent density of the lower ply;    k) the basis weight of the lower ply is from about 100 gsm to about 1000 gsm;    l) apparent density of the lower ply is about 0.15 g/cc to about 0.25 g/cc; 
 m) the binder content (per cent by weight) in the lower ply is from about 1% to about 8%; and  
   n) the lower ply contains at least 30% superabsorbent particles of the basis weight of the lower ply; and    o) wherein the structure has a wet integrity greater than about 4.0 mN/gsm, softness greater than 8.0/J, pliability greater than about 70/N, and providing a substantially dry liquid-accepting surface after receiving a quantity of liquid.    
     
     
         8 . A method of manufacturing an absorbent structure having wet integrity greater than about 6.0 mN/gsm, softness greater than 8.0/J, pliability greater than about 70/N, and providing a substantially dry liquid-accepting surface after receiving a quantity of liquid, the structure comprising: 
 a) providing a top stratum comprising synthetic matrix fibers bonded with a binder, the matrix fibers having length from about 2 to about 15 mm;    b) providing a middle stratum in fluid communication with the top stratum, the middle stratum comprising natural fibers, superabsorbent polymer particles and a binder; and    c) providing a bottom stratum in fluid communication with the middle stratum, comprising natural fibers and a binder.    
     
     
         9 . The method of  claim 8 , wherein superabsorbent polymer particles are placed at least in one of the strata in longitudinal discrete lanes along the length of the core, the lanes including from about 70% to about 100% superabsorbent polymer particles, and the lanes being separated by adjacent lanes including fibers and a binder.  
     
     
         10 . A method of manufacturing an absorbent structure, comprising: 
 a) providing a top stratum comprising polyester fibers bonded with latex in an amount of 15 to 25% by weight of the top stratum, the matrix fibers having length from about 4 mm to about 8 mm and having thickness from about 9 to about 15 denier per fiber, the basis weight of the top stratum being from about 40 to about 60 gsm;    b) providing a middle stratum in fluid communication with the top stratum, the middle stratum comprising softwood fluff fiber, superabsorbent polymer particles, and binder fiber, the content of the superabsorbent polymer particles being from about 30 to 40% of the basis weight of the middle stratum, the content of the binder fibers being from about 6 to about 12% of the basis weight of the middle stratum, and the basis weight of the middle stratum being from about 150 to about 200 gsm; and    c) providing a bottom stratum in fluid communication with the middle stratum, comprising softwood fluff and binder fibers, the content of the binder fibers being from about 8 to about 16% of the basis weight of the bottom stratum, and the basis weight of the bottom stratum being from about 60 to about 120 gsm,    wherein the density of the structure is from about 0.05 to about 0.3 g/cc, and the structure has a wet integrity greater than about 6.0 mN/gsm, softness greater than 8.0/J and pliability greater than about 70/N.    
     
     
         11 . A method of manufacturing an absorbent structure, comprising: 
 a) providing a top stratum comprising polyester matrix fibers bonded with latex in an amount of 15 to 25% by weight of the top stratum, the matrix fibers having length from about 4 mm to about 8 mm and having thickness from about 9 to about 15 denier per fiber, the basis weight of the top stratum being from about 40 to about 60 gsm;    b) providing a middle stratum in fluid communication with the top stratum, the middle stratum comprising softwood fluff fiber, superabsorbent polymer particles, and binder fiber, the content of the superabsorbent polymer particles being from about 40 to 60% of the basis weight of the middle stratum, the content of the binder fibers being from about 6 to about 12% of the basis weight of the middle stratum, and the basis weight of the middle stratum being from about 200 to about 280 gsm; and    c) providing a bottom stratum in fluid communication with the middle stratum, comprising softwood fluff and binder fibers, the content of the binder fibers being from about 8 to about 16% of the basis weight of the bottom stratum, and the basis weight of the bottom stratum being from about 60 to about 120 gsm,    wherein the density of the structure is from about 0.05 to about 1.0 g/cc, and the structure has a wet integrity greater than about 6.0 mN/gsm, softness greater than 8.0/J and pliability greater than about 70/N.