Abstract: A single-screw extruder for changing a morphology of superabsorbent polymer gel. The single-screw extruder has an input aperture, a channel, a screw and an output aperture. The screw in the invention has a first pitch value of a pitch of the screw flights along the conveying zone of the channel and, following in conveying direction, has a second pitch value of the pitch of the screw flights along the conveying zone of the channel, where the second pitch value is smaller than the first pitch value.

Abstract: A single-screw extruder for changing a morphology of a superabsorbent polymer, specifically a polymer gel. The single-screw extruder has an input aperture, a channel, a screw and an output aperture. The screw has a pitch value of a pitch of the screw flights along the conveying zone of the channel, where the channel has a mixing-element arrangement with at least one mixing element which protrudes into the channel of the single-screw extruder and which is configured for the mixing of the SAP polymer gel.

Abstract: A process for producing superabsorbent particles, comprising polymerization of a monomer preparation, drying of the resultant aqueous polymer gel, grinding, classifying and thermal surface postcrosslinking, wherein the monomer preparation is produced by mixing an aqueous monomer solution and a foamed aqueous surfactant solution.

Abstract: A single-screw extruder for changing a morphology of superabsorbent polymer gel. The single-screw extruder has an input aperture, a channel, a screw and an output aperture. The screw in the invention has a first pitch value of a pitch of the screw flights along the conveying zone of the channel and, following in conveying direction, has a second pitch value of the pitch of the screw flights along the conveying zone of the channel, where the second pitch value is smaller than the first pitch value.

Abstract: A single-screw extruder for changing a morphology of a superabsorbent polymer, specifically a polymer gel. The single-screw extruder has an input aperture, a channel, a screw and an output aperture. The screw has a pitch value of a pitch of the screw flights along the conveying zone of the channel, where the channel has a mixing-element arrangement with at least one mixing element which protrudes into the channel of the single-screw extruder and which is configured for the mixing of the SAP polymer gel.

Abstract: A process for producing water-absorbing polymer particles is provided, comprising a) a polymerization step in which an aqueous monomer solution comprising at least one ethylenically unsaturated monomer M which bears acid groups and may have been at least partly neutralized and at least one crosslinker is polymerized to obtain an aqueous polymer gel; b) a pelletization step in which the aqueous polymer gel having a solids content of 35 to 70% by weight and a temperature of 75 to 125° C. is forced from a high-pressure zone through a die plate into a low-pressure zone and pellets are obtained, the pressure differential between the high-pressure zone and the low-pressure zone being 4 to less than 14 bar and the orifice ratio of the die plate being 30 to 80%; c) a drying step in which the pellets are dried to a moisture content of less than 10% by weight; d) a grinding step and a classifying step to obtain water-absorbing polymer particles; and e) surface crosslinking of the water-absorbing polymer particles.

Abstract: Crosslinked polymer particles having a) a proportion of particles having a particle size of 150 to 300 ?m of at least 20% by weight, b) a free swell rate of the entirety of the polymer particles FSRoverall of at least 0.25 g/g·s, c) a difference ?FSR of at least 0.15, d) a centrifuge retention capacity CRC of at least 25.0 g/g, and e) a permeability of the swollen gel bed SFC of at least 90×10?7 cm3·s/g are disclosed.

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 is provided, comprising a) a polymerization step in which an aqueous monomer solution comprising at least one ethylenically unsaturated monomer M which bears acid groups and may have been at least partly neutralized and at least one crosslinker is polymerized to obtain an aqueous polymer gel; b) a pelletization step in which the aqueous polymer gel having a solids content of 35 to 70% by weight and a temperature of 75 to 125° C. is forced from a high-pressure zone through a die plate into a low-pressure zone and pellets are obtained, the pressure differential between the high-pressure zone and the low-pressure zone being 4 to less than 14 bar and the orifice ratio of the die plate being 30 to 80%; c) a drying step in which the pellets are dried to a moisture content of less than 10% by weight; d) a grinding step and a classifying step to obtain water-absorbing polymer particles; and e) surface crosslinking of the water-absorbing polymer particles.

Abstract: Water-absorbing polymer particles are formed from crosslinked polymer chains comprising predominantly polymerized units of at least partly neutralized acrylic acid. They have a) a proportion of particles having a particle size of 150 to 300 ?m of at least 20% by weight, b) a free swell rate of the entirety of the polymer particles FSRoverall of at least 0.25 g/g·s, c) a difference ?FSR of at least 0.15, d) a centrifuge retention capacity CRC of at least 25.0 g/g, and e) a permeability of the swollen gel bed SFC of at least 90×10?7 cm3·s/g. ?FSR is defined as =?FSR=FSR150-300 ?m?FSRoverall in which FSR150-300 ?m represents the free swell rate of the polymer particles having a particle size of 150 to 300 ?m. The absorption capacity of the entirety of the polymer particles is substantially utilized even in the case of segregation of particles of different size.

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: An aqueous polymer dispersion is prepared by reacting at least one olefin in the presence of at least one polymerization catalyst and one emulsifier in an aqueous medium by a process wherein the polymerization catalyst is prepared in an in situ reaction by reacting the ligand compound 2,6-dichloro-para-benzoquinone (Ia) and/or 2,3,6-trichloro-para-benzoquinone (Ib) with a phosphine compound or diphosphine compound and with a metal compound and the polymerization reaction is effected in an aqueous medium.

Abstract: The present invention relates to a process for the preparation of polymers by controlled free radical polymerization of monomers capable of free radical polymerization in the presence of 1,2-dithiol-3-thiones as chain transfer agents.

Abstract: Process for the emulsion polymerization of one or more olefins by reacting a quinoid compound with a metal compound and a phosphine compound which is substituted by at least one polar radical and subsequently using the reaction product for the polymerization or copolymerization of olefins in water or in a solvent mixture which contains at least 50% by weight of water and at least one emulsifier.

Abstract: Process for the emulsion polymerization of one or more olefins by reacting a quinoid compound with a metal compound and a phosphine compound which is substituted by at least one polar radical and subsequently using the reaction product for the polymerization or copolymerization of olefins in water or in a solvent mixture which contains at least 50% by weight of water and at least one emulsifier.

Abstract: Process for the emulsion polymerization of one or more olefins by preparing a catalyst by reacting a quinoid compound with a metal compound and a phosphine compound which is substituted by at least one polar radical; and subsequently (co)polymerizing said one or more olefins in water or in a solvent mixture which contains at least 50% by weight of water and at least one emulsifier.

Abstract: An aqueous polymer dispersion is prepared by reacting at least one olefin in. the presence of at least one polymerization catalyst and one emulsifier in an aqueous medium by a process wherein the polymerization catalyst is prepared in an in situ reaction by reacting the ligand compound 2,6-dichloro-para-benzoquinone (Ia) and/or 2,3,6-trichloro-para-benzoquinone (Ib) with a phosphine compound or diphosphine compound and with a metal compound and the polymerization reaction is effected in an aqueous medium.

Abstract: Process for the emulsion polymerization of one or more olefins by reacting a quinoid compound with a metal compound and a phosphine compound which is substituted by at least one polar radical and subsequently using the reaction product for the polymerization or copolymerization of olefins in water or in a solvent mixture which contains at least 50% by weight of water and at least one emulsifier.