Water-absorbing composites, preparation processes thereof and water-absorbing articles

Abstract

A water-absorbing composite, containing water-absorbing polymer particles immobilized on a fibrous substrate wherein at least a part of said water-absorbing polymer particles consist of primary particles having an average particle diameter of about 50-1000 μm, wherein about 30% by weight or more of said primary particles are combined to form agglomerates having a shape satisfying the conditions below while nearly maintaining their primary particle shapes and a part of particles of said agglomerates are not adhered to said fibrous substrate. This water-absorbing composite shows excellent water-absorbing properties and a high water-absorbing speed, and most of the highly water-absorbing polymer is stably immobilized on the fibrous substrate and the immobility of swollen gel after absorbing water is also excellent. Average particle diameter (D) 100≦D≦3000 μm Average relative displacement of the direction by direction analysis (θ) 10≦θ≦25 Frequency analysis 5 Hz/20 Hz intensity ratio (k) 0.6≦k≦0.9 Agglomerate maximum length (L)/minimum length (l) ratio 1.2≦L/l≦15.0.

1 - 23  (canceled)  
     
     
         24 . A process for preparing a water-absorbing composite, comprising; 
 a) forming droplets of a reaction mixture initiated by mixing a) an aqueous solution of a polymerizable monomer giving a water-absorbing polymer with b) a redox polymerization initiator in a gas phase;    b) combining said droplets into agglomerates while nearly maintaining their primary particle shapes in the gas phase or on a fibrous substrate, or both;    c) supporting said agglomerates formed in the gas phase on said fibrous substrate; and then    d) completing polymerization of said agglomerates on said fibrous substrate to immobilize said agglomerates on said fibrous substrate.    
     
     
         25 . The process of  claim 24 , wherein said polymerizable monomer has a polymerization degree of about 20-97% when it comes into contact with said fibrous substrate.  
     
     
         26 . The process of  claim 24 , wherein said droplets of said reaction mixture are formed by 
 mixing a first solution containing an oxidizing agent forming the redox polymerization initiator and the aqueous polymerizable monomer solution and a second solution containing a reducing agent forming the redox polymerization initiator and the aqueous polymerizable monomer solution in a gas phase.    
     
     
         27 . The process of  claim 26 , wherein said mixing is performed by colliding said first solution and said second solution in a liquid column state.  
     
     
         28 . The process of  claim 24 , wherein said polymerizable monomer is based on an aliphatic unsaturated carboxylic acid or a salt thereof.  
     
     
         29 . The process of  claim 24 , wherein said polymerizable monomer is based on acrylic acid in which 20 mol % or more of the carboxyl group is neutralized into an alkali metal salt or an ammonium salt.  
     
     
         30 . The process of  claim 24 , wherein the oxidizing agent forming said redox polymerization initiator is hydrogen peroxide and the reducing agent is L-ascorbic acid or an L-ascorbic acid alkali metal salt.  
     
     
         31 . The process of  claim 24 , wherein said fibrous substrate comprises synthetic fibers, natural fibers, or semisynthetic fibers.  
     
     
         32 - 51  (Canceled)