Abstract: A process for producing superabsorbents, comprising polymerization of a monomer solution and thermal surface postcrosslinking, wherein the monomer solution comprises at least 0.75% by weight of a hydroxyphosphonic acid or salts thereof, calculated on the basis of the total amount of monomer used, and at least 0.09% by weight of aluminum cations, calculated on the basis of the total amount of polymer particles used, is added to the polymer particles before, during or after the thermal surface postcrosslinking.

Abstract: A process for producing superabsorbents, comprising polymerization of a monomer solution and thermal surface postcrosslinking, wherein the monomer solution comprises at least 0.75% by weight of a hydroxyphosphonic acid or salts thereof, calculated on the basis of the total amount of monomer used, and at least 0.09% by weight of aluminum cations, calculated on the basis of the total amount of polymer particles used, is added to the polymer particles before, during or after the thermal surface postcrosslinking.

Abstract: A process for producing superabsorbents, comprising polymerization of a monomer solution and thermal surface postcrosslinking, wherein the monomer solution comprises at least 0.75% by weight of a hydroxyphosphonic acid or salts thereof, calculated on the basis of the total amount of monomer used, and at least 0.09% by weight of aluminum cations, calculated on the basis of the total amount of polymer particles used, is added to the polymer particles before, during or after the thermal surface postcrosslinking.

Abstract: The invention relates to a process for producing superabsorbents, comprising the preparation of partly neutralized acrylic acid by the steps (i) preparing an over-neutralized acrylic acid having a degree of neutralization of at least 100.1 mol-% by mixing of an acrylic acid 1 and a base and (ii) preparing a neutralized acrylic acid having a degree of neutralization from 50 to 85 mol-% by mixing of the over-neutralized acrylic acid and an acrylic acid 2, wherein the content of dimeric acrylic acid in the acrylic acid 2 is lower than the content of dimeric acrylic acid in the acrylic acid 1.

Abstract: The invention relates to a process for producing superabsorbents, comprising the preparation of partly neutralized acrylic acid by the steps (i) preparing an over-neutralized acrylic acid having a degree of neutralization of at least 100.1 mol-% by mixing of an acrylic acid 1 and a base and (ii) preparing a neutralized acrylic acid having a degree of neutralization from 50 to 85 mol-% by mixing of the over-neutralized acrylic acid and an acrylic acid 2, wherein the content of dimeric acrylic acid in the acrylic acid 2 is lower than the content of dimeric acrylic acid in the acrylic acid 1.

Abstract: A process for producing water-absorbing polymer particles having high free swell rate and high centrifuge retention capacity with simultaneously high permeability of the swollen gel bed by polymerization of an aqueous monomer solution in a polymerization reactor having at least two shafts (kneaders) which rotate in an axially parallel manner, subsequent extrusion at high temperatures and thermal surface postcrosslinking.

Abstract: A process for producing water-absorbing polymer particles with high free swell rate and high permeability by polymerization of an aqueous monomer solution or suspension to give an aqueous polymer gel, wherein a thermal blowing agent essentially free of inorganic acid anions is mixed into the polymer gel, and subsequent thermal drying of the polymer gel.

Abstract: A process for producing water-absorbing polymer particles with high free swell rate and high permeability by polymerization of an aqueous monomer solution or suspension to give an aqueous polymer gel, wherein a thermal blowing agent essentially free of inorganic acid anions is mixed into the polymer gel, and subsequent thermal drying of the polymer gel.

Abstract: A process for producing water-absorbing polymer particles with high free swell rate and high permeability by polymerization of an aqueous monomer solution or suspension to give an aqueous polymer gel, wherein a thermal blowing agent essentially free of inorganic acid anions is mixed into the polymer gel, and subsequent thermal drying of the polymer gel.

Abstract: A process for producing water-absorbing polymer particles having high free swell rate and high centrifuge retention capacity with simultaneously high permeability of the swollen gel bed by polymerization of an aqueous monomer solution in a polymerization reactor having at least two shafts (kneaders) which rotate in an axially parallel manner, subsequent extrusion at high temperatures and thermal surface postcrosslinking.

Abstract: A process for producing water-absorbing polymer particles, comprising polymerization of a monomer solution or suspension, classification and drying of the resulting moist polymer gel, and comminution of the coarse fraction removed in the classification of the moist polymer gel, wherein the classification of the moist polymer gel is performed by means of a plurality of bar decks arranged in a cascade in a vibrating frame.

Abstract: A process for producing water-absorbing polymer particles by polymerizing an aqueous monomer solution in a kneader having at least two shafts in axially parallel rotation, wherein the reaction mixture is transported in axial direction and the region at the start of the kneader is trace-heated.

Abstract: A process for producing water-absorbing polymer particles, comprising polymerization of a monomer solution or suspension, classification and drying of the resulting moist polymer gel, and comminution of the coarse fraction removed in the classification of the moist polymer gel, wherein the classification of the moist polymer gel is performed by means of a plurality of bar decks arranged in a cascade in a vibrating frame.

Abstract: A process for producing water-absorbing polymer particles, wherein an aqueous polymer gel is dried in a forced-air belt drier on a circulating conveyor belt and the surface of the conveyor belt has a multitude of elevations or depressions which are suitable for restricting the mobility of the aqueous polymer gel in transverse direction.

Abstract: A process for producing water-absorbing polymer particles by polymerizing an aqueous monomer solution in a kneader having at least two shafts in axially parallel rotation, wherein the reaction mixture is transported in axial direction and the region at the start of the kneader is trace-heated.

Abstract: A process for producing water-absorbing polymer particles by polymerizing a monomer solution or suspension comprising an ethylenically unsaturated monomer bearing acid groups, an ethylenically unsaturated monomer, a crosslinker and an initiator.