Abstract: The invention relates to a classification process for superabsorbent polymer particles, comprising classifying the water-absorbent polymer particles in a screen machine under reduced pressure wherein the pressure above the uppermost sieve is from 0 to 4.0 mbar per sieve higher than below the undermost sieve.

Abstract: A production process for production of water absorbing polymer particles, including drying an aqueous polymer gel in a belt drier with a conveyor belt having a drier setup in the interior, in which drying air in the interior of the drier setup is conducted in countercurrent counter to the conveying direction and the interior of the drier setup is kept substantially at a reduced pressure relative to the ambient pressure outside the drier setup, and the interior has and/or forms a pressure zone, and is especially divided into a number of pressure zones.

Abstract: A production process for production of water-absorbing polymer particles including drying an aqueous polymer gel in a belt drier with a conveyor belt. The belt drier is formed with a drier setup substantially comprising the conveyor belt and an air recycling conduit downstream of the drier setup for air recycling, where recycled air is withdrawn from the drier setup and fed back to the drier setup via the air recycling conduit.

Abstract: A process for preparing water-absorbing polymer beads by polymerizing droplets comprising at least one monomer in a gas phase surrounding the droplets, the droplets being obtained by enveloping a first monomer solution with a second monomer solution and polymerizing the second monomer solution and polymerizing to give a more highly crosslinked polymer than the first monomer solution.

Abstract: A process for producing superabsorbents, comprising polymerization, drying, crushing, pneumatic conveying, comminuting and classifying, wherein the gas temperature at the end of the pneumatic conveying is from 50 to 95° C.

Abstract: Filling process for superabsorbent polymer particles The invention relates to a filling process for superabsorbent polymer particles, comprising discharging the superabsorbent polymer particles out of a silo into bulk container for shipping, wherein the filling level of the silo during filling of the bulk container is never less than 20%, in order to avoid particle segregation.

Abstract: A process for preparing water-absorbing polymer beads with high permeability by polymerizing droplets of a monomer solution, comprising monomers bearing acid groups, in a gas phase surrounding the droplets, wherein the monomer solution comprises polyvalent cations and the polymer beads have a mean diameter of at least 150 ?m.

Abstract: The invention relates to a heat exchanger for heating gas to a temperature in the range from 150 to 400° C., wherein the gas is heated by indirect heat transfer and all the surfaces of the walls of the heat exchanger which come into contact with the gas have been hot dip galvanized and the surfaces which come into contact with the gas, after the hot dip galvanization, have been heat treated at a temperature in the range from 400 to 750° C. The invention further relates to the use of the heat exchanger.

Abstract: The invention relates to a process for producing water-absorbing polymer particles, comprising the steps of: •—processing an aqueous polymer gel from polymerization of a monomer solution or suspension, •—drying the aqueous polymer gel in a conveyer dryer, in particular in a forced air conveyer dryer, wherein •—the conveyer dryer has a circulating conveyer belt and the aqueous polymer gel is conveyed on the circulating conveyer belt, and wherein •—the circulating conveyer belt is formed as a circulating plate conveyer belt, comprising a number of belt plates separated by a hinge line of a hinge assembly and each belt plate having a surface for receiving the aqueous polymer gel, wherein said hinge assembly comprises a knuckle joint (301) with the hinge line in form of a straight hinge line.

Abstract: A process for producing water-absorbing polymer particles, wherein surface postcrosslinked water-absorbing polymer particles are remoisturized and delivered pneumatically, and wherein the time between remoisturization and pneumatic delivery is less than one hour.

Abstract: The invention relates to a process for producing water-absorbing polymer particles, comprising the steps of: •—processing an aqueous polymer gel from polymerization of a monomer solution or suspension, •—drying the aqueous polymer gel in a conveyer dryer, in particular in a forced air conveyer dryer, wherein •—the conveyer dryer has a circulating conveyer belt and the aqueous polymer gel is conveyed on the circulating conveyer belt, and wherein •—the circulating conveyer belt is formed as a circulating plate conveyer belt, comprising a number of belt plates separated by a hinge line of a hinge assembly and each belt plate having a surface for receiving the aqueous polymer gel, wherein said hinge assembly comprises a knuckle joint (301) with the hinge line in form of a straight hinge line.

Abstract: The invention relates to a process for producing water-absorbing polymer particles, comprising the steps of: •—processing an aqueous polymer gel from polymerization of a monomer solution or suspension, •—drying the aqueous polymer gel in a conveyer dryer, in particular in a forced air conveyer dryer, wherein •—the conveyer dryer has a circulating conveyer belt and the aqueous polymer gel is conveyed on the circulating conveyer belt, and wherein •—the circulating conveyer belt is formed as a circulating plate conveyer belt, comprising a number of belt plates separated by a hinge line of a hinge assembly and each belt plate having a surface for receiving the aqueous polymer gel, wherein said hinge assembly comprises a knuckle joint (301) with the hinge line in form of a straight hinge line.

Abstract: A production process for production of water-absorbing polymer particles including drying an aqueous polymer gel in a belt drier with a conveyor belt. The belt drier is formed with a drier setup substantially comprising the conveyor belt and an air recycling conduit downstream of the drier setup for air recycling, where recycled air is withdrawn from the drier setup and fed back to the drier setup via the air recycling conduit.

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

Abstract: The present invention relates to an apparatus for producing water-absorbing polymer particles by polymerizing monomers on a continuous conveyor belt, wherein joins of the conveyor belt and/or damage on the conveyor belt surface have been sealed with a sealing composition.

Abstract: The invention relates to the production of superabsorbent polymers on a continuous belt reactor, comprising at least one rotating knife that cuts the formed polymer gel at the end of the continuous belt reactor, wherein the length of the cutting edge is at least 1 cm and the cutting edge is non-parallel to the rotation axis.

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 by polymerizing droplets of a monomer solution, where the monomer solution comprises at least two initiators, one of the initiators is a peroxide with the exception of persulfate, and the molar ratio of peroxide to further initiator is at least 1:8, the water-absorbing polymer particles themselves, and hygiene articles comprising these water-absorbing polymer particles.

Abstract: A process for continuously classifying water-absorbing polymer beads by means of at least one screen, at least one screen having at least one guide device on the screen surface.

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.