Absorbent inserts, method of producing them and their use

Abstract

The invention relates to an absorbent insert for foodstuff packagings, the liquid-absorbing component of which is a superabsorbent polymer which, in a hitherto unrivaled fashion, persistently absorbs and retains large quantities of liquid even under high pressure load, protects the foodstuffs from bacterial decay, and prevents contamination of the packagingd goods by migrating soluble constituents of the polymer. This combination of properties of the superabsorbers used is expressed by the Q SAP 0.3 quotient of retention according to the tea bag test+absorption against pressure (AAP) 0.3, divided by the amount of solubles (LA), which quotient is at least 20. Superabsorbers having such properties are obtained by using special combinations of crosslinkers. Furthermore, the invention relates to a process for producing said absorbent inserts and their use in foodstuff packagings, as ice substitute, and as leak-proofing means in transport packagings.

1 - 21 . (Canceled)  
     
     
         22 . An absorbent insert for a packaging, comprising: 
 a top and a bottom covering layer; and    a core which absorbs an aqueous liquid and includes an absorbent polymer;    wherein the absorbent polymer has a quotient Q SAP 0.3  calculated from retention and absorption under a pressure of 0,3 psi (21 g/cm 2 ) and from an amount of a soluble ratio of at least 20 and a retention of at least 22 g/g.    
     
     
         23 . The absorbent insert of  claim 22 , wherein the polymer has a Q SAP 0,3  of at least 30.  
     
     
         24 . The absorbent insert according to  claim 22 , wherein the absorbent polymer has a retention of at least 25 g/g.  
     
     
         25 . The absorbent insert according to  claim 22 , wherein the absorbent polymer has an absorption under pressure of at least 15 g/g.  
     
     
         26 . The absorbent insert according to  claim 22 , wherein the soluble ratio of the absorbent polymer is 3.5 wt.-%.  
     
     
         27 . The absorbent insert according to  claim 22 , wherein having a migration value of ≦15 mg/g.  
     
     
         28 . The absorbent insert according to claims  22 , wherein the top and bottom covering layer comprise a plastic or cellulose film, a fabric or a fleece; and 
 at least one part of the covering layer film is permeable to water or an aqueous liquid as a result of a perforation.    
     
     
         29 . Absorbent insert according to  claim 22 , wherein the core comprises fleece, a fiber, a fabric; 
 wherein the polymer absorbing an aqueous liquid is dispersed and optionally fixed.    
     
     
         30 . Absorbent insert according to  claim 29 , wherein the core has an arrangement in layers of the absorbent polymer part within the core of fiber and fabric.  
     
     
         31 . Absorbent insert according to  claim 29  or  30 , wherein the fiber is a hollow fiber.  
     
     
         32 . Absorbent insert according to  claim 22 , wherein the absorbent polymer is made from a partially neutralized monoethylenically unsaturated monomer containing an acid group and, optionally another monomer copolymerizable therewith; 
 wherein the absorbent polymer is further made from crosslinker as well as a polymer optionally serving as graft basis.    
     
     
         33 . Absorbent insert according to  claim 32 , wherein said unsaturated monomer containing an acid group is selected from the group consisting of an acrylic acid, a methacrylic acid, vinylacetic acid, vinyl sulfonic acid, (meth)allylsulfonic acid, maleic acid, 2-acrylamido-2-methylpropanesulfonic acid and a mixture thereof.  
     
     
         34 . A method of packaging foodstuff, comprising: 
 packaging a foodstuff in a package captaining the absorbent insert for a package, comprising a top and a bottom covering layer and a core which absorbs an aqueous liquid and includes an absorbent polymer;    wherein the absorbent polymer has a quotient Q SAP 0,3  calculated from retention and absorption under a pressure of 0,3 psi (21 g/cm 2 ) and from the amount of soluble ratio of at least 20 and a retention of at least 22 g/g.    
     
     
         35 . A method of making an ice for a packaging application, comprising: 
 (a) providing an absorbent insert for a packaging, comprising a top and a bottom covering layer and a core which absorbs an aqueous liquid and includes an absorbent polymer, wherein the absorbent polymer has a quotient Q SAP 0,3  calculated from retention and absorption under a pressure of 0,3 psi (21 g/cm 2 ) and from the amount of soluble ratio of at least 20 and a retention of at least 22 g/g;    (b) soaking said absorbent insert in water, thereby obtaining a soaked insert; and    (c) freezing the soaked insert.