Absorbent structure and method for producing the same

Abstract

The invention relates to an absorbent structure ( 30, 38, 50, 58, 62, 66 ) that is produced on the basis of superabsorbent polymer materials. Said superabsorbent polymer materials are interlinked by means of a thermoplastic polymer. The inventive structure is produced by extruding the superabsorbent polymer materials with a moisture content of at least 0.5 wt.-% based on the overall weight of the superabsorbent polymer and evaporating the liquid of the superabsorbent polymer materials and inducing foaming of the structure.

What is claimed is:  
     
         1 . Absorbent structure ( 30 ,  38 ,  50 ,  58 ,  62 ,  66 ) formed on the basis of superabsorbent polymer materials, where the superabsorbent polymer materials are bonded together by a thermoplastic polymer, produced by extruding the thermoplastic polymer and superabsorbent polymer materials with a moisture content of at least 0.5% by weight relative to the total mass of the superabsorbent polymer materials and thereby the fluid in the superabsorbent polymer materials is evaporated and foaming of the structure is induced.  
     
     
         2 . Absorbent structure in accordance with  claim 1 , wherein superabsorbent polymer materials having a moisture content of at least 1% by weight are used for extrusion.  
     
     
         3 . Absorbent structure in accordance with  claim 2 , wherein superabsorbent polymer materials having a moisture content of at least 4% by weight are used for extrusion.  
     
     
         4 . Absorbent structure ( 30 ,  38 ,  50 ,  58 ,  62 ,  66 ) in accordance with one of the preceding claims, wherein the structure has a retention capacity of at least 10 g/g.  
     
     
         5 . Absorbent structure ( 30 ,  38 ,  50 ,  58 ,  62 ,  66 ) in accordance with one or more of the preceding claims  1 - 4 , wherein the percentage by weight of the thermoplastic polymer is less than 30% by weight of the absorbent structure.  
     
     
         6 . Absorbent structure ( 30 ,  38 ,  50 ,  58 ,  62 ,  66 ) in accordance with  claim 5 , wherein the percentage by weight of the thermoplastic polymer is less than 20% by weight of the absorbent structure.  
     
     
         7 . Absorbent structure ( 30 ,  38 ,  50 ,  58 ,  62 ,  66 ) in accordance with  claim 6 , wherein the percentage by weight of the thermoplastic polymer is less than 10% by weight of the absorbent structure.  
     
     
         8 . Absorbent structure ( 30 ,  38 ,  50 ,  58 ,  62 ,  66 ) in accordance with one or more of the preceding claims, wherein the thermoplastic polymer comprises a polyolefin, specifically polypropylene and/or polyethylene and/or ethyl vinyl acetate (EVA).  
     
     
         9 . Absorbent structure ( 30 ,  38 ,  50 ,  58 ,  62 ,  66 ) in accordance with one or more of the preceding claims, wherein the degree of foaming is at least 20%.  
     
     
         10 . Absorbent structure ( 30 ,  38 ,  50 ,  58 ,  62 ,  66 ) in accordance with one or more of the preceding claims, wherein the structure comprises 3%-20% by weight, specifically 5%-10% by weight, fibers as additives.  
     
     
         11 . Absorbent structure ( 30 ,  38 ,  50 ,  58 ,  62 ,  66 ) in accordance with one or more of the preceding claims, wherein its basis weight varies in the longitudinal and/or transverse direction.  
     
     
         12 . Absorbent structure ( 30 ,  38 ,  50 ,  58 ,  62 ,  66 ) in accordance with one or more of the preceding claims, wherein a surfactant substance is added as an additive.  
     
     
         13 . Disposable hygine article, specifically diaper, sanitary napkin, incontinence pad, having a specifically multilayer absorbent core, characterized by an absorbent core layer from an absorbent structure ( 30 ,  38 ,  50 ,  58 ,  62 ,  66 ) in accordance with one or more of the preceding claims.  
     
     
         14 . Hygiene article in accordance with  claim 13 , wherein the absorbent core layer ( 70 ) is located on the side of a fluid distribution and interim retention layer ( 72 ) facing away from the body.  
     
     
         15 . Hygiene article in accordance with  claim 14 , wherein the fluid distribution and interim retention layer ( 72 ) comprises a thermoplastic polymer and is extruded under the addition of a blowing agent.  
     
     
         16 . Hygiene article in accordance with  claim 15 , wherein the fluid distribution and intermediate retention layer ( 72 ) does not comprise any superabsorbent polymer materials.  
     
     
         17 . Hygiene article in accordance with  claim 15  or  16 , wherein the fluid distribution and intermediate retention layer ( 72 ) has a degree of foaming of more than 20%.  
     
     
         18 . Hygiene article in accordance with  claim 15 ,  16  or  17 , wherein the fluid distribution and intermediate retention layer ( 72 ) contains as additive 1%-20% by weight, specifically 5%-15% by weight, fibers.  
     
     
         19 . Hygiene article in accordance with one of claims  13 - 18  having a fluid impervious film ( 68 ) on the side of the absorbent core layer ( 70 ) facing away from the body, wherein the film ( 68 ) is extruded together with the absorbent core layer ( 70 ).  
     
     
         20 . Hygiene article in accordance with one of claims  13 - 19 , wherein the absorbent core has a varying thickness in the longitudinal direction ( 44 ) of the article.  
     
     
         21 . Hygiene article in accordance with one of claims  13 - 20 , wherein the absorbent core has a varying thickness in the transverse direction ( 40 ) of the article.  
     
     
         22 . Hygiene article in accordance with one of claims  13 - 21 , wherein the absorbent core layer has wall sections ( 46 ) on both sides running in the longitudinal direction ( 44 ) of the article and extending upward toward the wearer, which form a leakage barrier.  
     
     
         23 . Hygiene article in accordance with one of claims  13 - 22 , wherein the absorbent core layer has a wall section running essentially in the transverse direction of the article and extending upward toward the wearer.  
     
     
         24 . Method for producing an absorbent structure in accordance with one or more of claims  1 - 12 , comprising the following steps: 
 introduction of a thermoplastic polymer into an extrusion apparatus,    introduction of a superabsorbent particulate polymer material having a moisture content of at least 0.5% by weight, specifically 1% by weight, specifically at least 4% by weight, into the extrusion apparatus,    melting the thermoplastic polymer material at temperatures below a melting or degradation temperature of the superabsorbent polymer material,    extrusion of the mix, whereby the fluid in the superabsorbent polymer material evaporates as pressure is reduced and results in foaming of the thermoplastic polymer, which bonds the particulate polymer materials together to create a matrix.    
     
     
         25 . Method in accordance with  claim 24 , wherein the percentage by weight of the superabsorbent polymer material is at least 70% by weight of the mix introduced into the extrusion apparatus.  
     
     
         26 . Method in accordance with  claim 24  or  25 , wherein the thermoplastic polymer becomes molten at temperatures of 80 to 200 degrees Celsius.  
     
     
         27 . Method in accordance with claims  24 ,  25  or  26 , wherein fibers are introduced as an additive into the extrusion apparatus.  
     
     
         28 . Method in accordance with one or more of claims  24 - 27 , wherein a surfactant substance is introduced as an additive into the extrusion apparatus.  
     
     
         29 . Method in accordance with one or more of claims  24 - 28 , wherein an extrusion cross-section is changed during extrusion.  
     
     
         30 . Method in accordance with  claim 29 , wherein the extrusion cross-section is changed in an oscillating fashion.  
     
     
         31 . Method in accordance with one or more of claims  24 - 30 , wherein the method is integrated into a production process for hygiene articles and therein the absorbent structure is extruded directly inside machinery for the high-speed production of hygiene articles.  
     
     
         32 . Method in accordance with  claim 31 , wherein inside the high-speed production machinery a double-layer absorbent core is formed by coextrusion of the layers, whereby the absorbent core comprises the absorbent structure ( 70 ) as absorbent core layer and a fluid distribution and intermediate retention layer ( 72 ) on the body-facing side of the core layer.  
     
     
         33 . Method in accordance with  claim 31  or  32 , wherein inside the high-speed production machinery a triple-layer absorbent core is formed by coextrusion of the layers, wherein the third layer is a fluid-impervious film ( 68 ) which is located on the side of the absorbent core layer facing away from the body.