Abstract: The invention relates generally to a process for the preparation of water-absorbent polymer particles, including the process steps of preparing particulate water-absorbent polymer and mixing the particulate water-absorbent polymer with an aqueous crosslinker solution and heat-treating the mixture of particulate water-absorbent polymer in a horizontally operated mixing device, wherein the horizontally operated mixing device is hydraulically driven. The invention also relates to water-absorbent polymer particles obtainable by such a process.

Abstract: The present invention relates to a continuous process for the production of a superabsorbent polymer comprising providing an acidic liquid aqueous monomer mixture containing dissolved oxygen; continuously feeding the aqueous monomer mixture to a reactor; introducing a source of carbonate or hydrogen carbonate into the aqueous monomer mixture prior to entry into the reactor thereby forming a gas phase comprising carbon dioxide and at least a part of the dissolved oxygen, the gas phase being dispersed in the liquid phase; subjecting the gas/liquid mixture to at least partial phase separation immediately prior to or after entry into the reactor and at least partially removing the separated gaseous phase; subjecting the liquid phase in the reactor to free-radical polymerization to obtain the superabsorbent polymer, and continuously removing the superabsorbent polymer from the reactor.

Abstract: The invention relates generally to a process for the preparation of water-absorbent polymer particles, including the process steps of preparing particulate water-absorbent polymer and mixing the particulate water-absorbent polymer with an aqueous crosslinker solution and heat-treating the mixture of particulate water-absorbent polymer in a horizontally operated mixing device, wherein the horizontally operated mixing device is hydraulically driven. The invention also relates to water-absorbent polymer particles obtainable by such a process.

Abstract: The present invention relates to a continuous process for the production of a superabsorbent polymer comprising providing an acidic liquid aqueous monomer mixture containing dissolved oxygen; continuously feeding the aqueous monomer mixture to a reactor; introducing a source of carbonate or hydrogen carbonate into the aqueous monomer mixture prior to entry into the reactor thereby forming a gas phase comprising carbon dioxide and at least a part of the dissolved oxygen, the gas phase being dispersed in the liquid phase; subjecting the gas/liquid mixture to at least partial phase separation immediately prior to or after entry into the reactor and at least partially removing the separated gaseous phase; subjecting the liquid phase in the reactor to free-radical polymerization to obtain the superabsorbent polymer, and continuously removing the superabsorbent polymer from the reactor.

Abstract: The present invention relates to a continuous process for the production of a superabsorbent polymer comprising providing an acidic liquid aqueous monomer mixture containing dissolved oxygen; continuously feeding the aqueous monomer mixture to a reactor; introducing a source of carbonate or hydrogen carbonate into the aqueous monomer mixture prior to entry into the reactor thereby forming a gas phase comprising carbon dioxide and at least a part of the dissolved oxygen, the gas phase being dispersed in the liquid phase; subjecting the gas/liquid mixture to at least partial phase separation immediately prior to or after entry into the reactor and at least partially removing the separated gaseous phase; subjecting the liquid phase in the reactor to free-radical polymerization to obtain the superabsorbent polymer, and continuously removing the superabsorbent polymer from the reactor.

Abstract: The present invention relates to a continuous process for the production of a superabsorbent polymer comprising providing an acidic liquid aqueous monomer mixture containing dissolved oxygen; continuously feeding the aqueous monomer mixture to a reactor; introducing a source of carbonate or hydrogen carbonate into the aqueous monomer mixture prior to entry into the reactor thereby forming a gas phase comprising carbon dioxide and at least a part of the dissolved oxygen, the gas phase being dispersed in the liquid phase; subjecting the gas/liquid mixture to at least partial phase separation immediately prior to or after entry into the reactor and at least partially removing the separated gaseous phase; subjecting the liquid phase in the reactor to free-radical polymerization to obtain the superabsorbent polymer, and continuously removing the superabsorbent polymer from the reactor.

Abstract: The present invention relates to a continuous process for the production of a superabsorbent polymer comprising providing an acidic liquid aqueous monomer mixture containing dissolved oxygen; continuously feeding the aqueous monomer mixture to a reactor; introducing a source of carbonate or hydrogen carbonate into the aqueous monomer mixture prior to entry into the reactor thereby forming a gas phase comprising carbon dioxide and at least a part of the dissolved oxygen, the gas phase being dispersed in the liquid phase; subjecting the gas/liquid mixture to at least partial phase separation immediately prior to or after entry into the reactor and at least partially removing the separated gaseous phase; subjecting the liquid phase in the reactor to free-radical polymerization to obtain the superabsorbent polymer, and continuously removing the superabsorbent polymer from the reactor.

Abstract: The present invention relates to superabsorbent polymer comprising the comprising the free radical polymerization product of an aqueous monomer mixture containing at least one ?,?-ethylenically unsaturated monomer; at least one monomer having at least two ?,?-ethylenically unsaturated groups; a crosslinking agent having at least two polymerizable double bonds; iron ions in an amount of from about 0.1 to about 3 wppm based on the total weight of the aqueous monomer mixture; and at least one chelating agent in an amount to provide a molar ratio of chelating agent to iron ion of from about 0.8 to about 4.0.

Abstract: The present invention relates to superabsorbent polymer comprising the comprising the free radical polymerization product of an aqueous monomer mixture containing at least one ?,?-ethylenically unsaturated monomer; at least one monomer having at least two ?,?-ethylenically unsaturated groups; a crosslinking agent having at least two polymerizable double bonds; iron ions in an amount of from about 0.1 to about 3 wppm based on the total weight of the aqueous monomer mixture; and at least one chelating agent in an amount to provide a molar ratio of chelating agent to iron ion of from about 0.8 to about 4.0.

Abstract: The present invention relates to process for the preparation of a superabsorbent polymer comprising the steps of a) subjecting an aqueous monomer mixture containing at least one ?,?-ethylenically unsaturated monomer; at least one monomer bearing at least two ?,?-ethylenically unsaturated groups; iron ions in an amount of 0.1 to 3 wppm based on the total weight of the aqueous monomer mixture; and at least one chelating agent in an amount to provide a mol ratio of chelating agent to iron ion of 0.8 to 4.0 to free radical polymerization in an reactor to obtain a super-absorbent polymer; and b) recovering the superabsorbent polymer, whereby if the process is continuous and is run in an agitated reactor the upper limit of the mol ratio of chelating agent to iron ion is 4.0 for a throughput of total reaction mixture through the reactor of at most 1.3 kg/h per liter reactor volume.

Abstract: In a wire saw that serves for cutting polygonal, columnar bricks out of an ingot of a generally inorganic crystalline material, more particularly a semiconductor material, a cutting yoke (5) having at least two angularly offset saw wire fields is provided that is displaceable in the saw feed direction (7). The yoke is coupled to a carrier (38) by means of an assembly of two rails (40, 42). In this manner, the yoke (5) is easily removable from the process chamber (1) of the wire saw by pulling one rail (42) out of the other rail (40) in order to perform maintenance operations etc. The saw wire in the cutting yoke (5) is guided in an essentially meander-shaped path so that the cutting wire essentially only extends in the wire fields (sections 14, 16) and on the sides of the frame (20) of the cutting yoke (5).

Abstract: The present invention relates to a process for the production of a superabsorbent polymer comprising preparing an aqueous mixture of monomers selected to provide after polymerization a superabsorbent polymer; feeding said monomer mixture to a reactor; subjecting the aqueous monomer mixture in the reactor to free-radical polymerization to obtain a superabsorbent polymer gel; removing the superabsorbent polymer gel from the reactor; and drying the superabsorbent polymer gel. Where at least one off-gas stream removed from any stage of the process is subjected to scrubbing with a basic aqueous solution prior to venting to obtain an aqueous scrubber solution that is at least partially recycled to any of the above steps of the process.

Abstract: The present invention relates to a process for the production of a superabsorbent polymer comprising preparing an aqueous mixture of monomers selected to provide after polymerization a superabsorbent polymer; feeding said monomer mixture to a reactor; subjecting the aqueous monomer mixture in the reactor to free-radical polymerization to obtain a superabsorbent polymer gel; removing the superabsorbent polymer from the reactor; and working-up the superabsorbent polymer removed from the reactor to obtain a final product, whereby a basic aqueous medium comprising carbonate and/or hydrogen carbonate is fed to the superabsorbent polymer gel.

Abstract: The present invention relates to process for the preparation of a superabsorbent polymer comprising the steps of a) subjecting an aqueous monomer mixture containing at least one ?,?-ethylenically unsaturated monomer; at least one monomer bearing at least two ?,?-ethylenically unsaturated groups; iron ions in an amount of 0.1 to 3 wppm based on the total weight of the aqueous monomer mixture; and at least one chelating agent in an amount to provide a mol ratio of chelating agent to iron ion of 0.8 to 4.0 to free radical polymerization in an reactor to obtain a super-absorbent polymer; and b) recovering the superabsorbent polymer, whereby if the process is continuous and is run in an agitated reactor the upper limit of the mol ratio of chelating agent to iron ion is 4.0 for a throughput of total reaction mixture through the reactor of at most 1.3 kg/h per liter reactor volume.

Abstract: The present invention relates to a continuous process for the production of a superabsorbent polymer comprising providing an acidic liquid aqueous monomer mixture containing dissolved oxygen; continuously feeding the aqueous monomer mixture to a reactor; introducing a source of carbonate or hydrogen carbonate into the aqueous monomer mixture prior to entry into the reactor thereby forming a gas phase comprising carbon dioxide and at least a part of the dissolved oxygen, the gas phase being dispersed in the liquid phase; subjecting the gas/liquid mixture to at least partial phase separation immediately prior to or after entry into the reactor and at least partially removing the separated gaseous phase; subjecting the liquid phase in the reactor to free-radical polymerization to obtain the superabsorbent polymer, and continuously removing the superabsorbent polymer from the reactor.

Abstract: The present invention relates to a process for the production of a superabsorbent polymer comprising preparing an aqueous mixture of monomers selected to provide after polymerization a superabsorbent polymer; feeding said monomer mixture to a reactor; subjecting the aqueous monomer mixture in the reactor to free-radical polymerization to obtain a superabsorbent polymer gel; removing the superabsorbent polymer gel from the reactor; and drying the superabsorbent polymer gel. Where at least one off-gas stream removed from any stage of the process is subjected to scrubbing with a basic aqueous solution prior to venting to obtain an aqueous scrubber solution that is at least partially recycled to any of the above steps of the process.

Abstract: The present invention relates to a process for the production of a superabsorbent polymer comprising preparing an aqueous mixture of monomers selected to provide after polymerization a superabsorbent polymer; feeding said monomer mixture to a reactor; subjecting the aqueous monomer mixture in the reactor to free-radical polymerization to obtain a superabsorbent polymer gel; removing the superabsorbent polymer from the reactor; and working-up the superabsorbent polymer removed from the reactor to obtain a final product, whereby a basic aqueous medium comprising carbonate and/or hydrogen carbonate is fed to the superabsorbent polymer gel.