摘要:
The invention relates to a neutralization process in which at least one ethylenically unsaturated carboxylic acid is neutralized at least partly with a base and at least one stream of the neutralization is determined continuously, and also to an apparatus for carrying out the process.
摘要:
A process for producing water-absorbing polymer particles with a low centrifuge retention capacity by polymerizing in a continuous kneading reactor under an inert gas volume flow of at most 10 m3/h per m3 of reactor volume.
摘要:
A process for producing water-absorbing polymer particles with a low centrifuge retention capacity by polymerizing in a continuous kneading reactor under an inert gas volume flow of at most 10 m3/h per m3 of reactor volume.
摘要:
A process for producing water-absorbing polymer particles, wherein an aqueous polymer gel is applied by means of a swivel belt to the conveyor belt of a forced-air belt drier, and the swivel belt, proceeding from one end position, is accelerated through a first pivot angle to an angular speed v1, decelerated through a second pivot angle to an angular speed v2 and decelerated through a third pivot angle to the other end position.
摘要:
A process for producing water-absorbing polymer particles, wherein an aqueous polymer gel is applied by means of a swivel belt to the conveyor belt of a forced-air belt drier, and the swivel belt, proceeding from one end position, is accelerated through a first pivot angle to an angular speed v1, decelerated through a second pivot angle to an angular speed v2 and decelerated through a third pivot angle to the other end position.
摘要:
The invention relates to a process for producing a water-absorbing resin by polymerization of a reaction mixture comprising at least one hydrophilic monomer and, if appropriate, at least one crosslinker in a reactor, which comprises admixing the reaction mixture with at least one first portion of a particulate additive before the reaction mixture has reached a residence time of 40% of the overall residence time in the reactor and with at least one second portion of a particulate additive when the reaction mixture has reached a residence time of 45% or more of the overall residence time in the reactor, the additive being selected from water-absorbing resin powders, fillers and mixtures thereof, the total solids content of monomer and additive being in the range from 30% to 60% by weight, the amount of additive being in the range from 5% to 50% by weight, based on the monomers, and the weight ratio of the first portion to the second portion of the additive being in the range from 10:1 to 1:5. The resin powder is recycled fine-sized material for example. Not only the residual monomer content, specifically the residual crosslinker content, but also the level of extractables in the water-absorbing resin are reduced by the method of addition described. A high fraction of additives can be incorporated without the properties of the water-absorbing resin obtained being adversely affected. The additives enter a sufficiently firm bond with the resin, so that no excessive dusting occurs on exposure to mechanical stress.
摘要:
A process for classifying water-absorbing polymer beads, wherein screens having different mesh sizes are used before and after the postcrosslinking to remove the oversize.
摘要:
The invention relates to a process for producing a water-absorbing resin by polymerization of a reaction mixture comprising at least one hydrophilic monomer and, if appropriate, at least one crosslinker in a reactor, which comprises admixing the reaction mixture with at least one first portion of a particulate additive before the reaction mixture has reached a residence time of 40% of the overall residence time in the reactor and with at least one second portion of a particulate additive when the reaction mixture has reached a residence time of 45% or more of the overall residence time in the reactor, the additive being selected from water-absorbing resin powders, fillers and mixtures thereof, the total solids content of monomer and additive being in the range from 30% to 60% by weight, the amount of additive being in the range from 5% to 50% by weight, based on the monomers, and the weight ratio of the first portion to the second portion of the additive being in the range from 10:1 to 1:5. The resin powder is recycled fine-sized material for example. Not only the residual monomer content, specifically the residual crosslinker content, but also the level of extractables in the water-absorbing resin are reduced by the method of addition described. A high fraction of additives can be incorporated without the properties of the water-absorbing resin obtained being adversely affected. The additives enter a sufficiently firm bond with the resin, so that no excessive dusting occurs on exposure to mechanical stress.
摘要:
A process for classifying water-absorbing polymer beads, wherein screens having different mesh sizes are used before and after the postcrosslinking to remove the oversize.
摘要:
A process for continuously preparing water-absorbing polymer beads, comprising the drying of a polymer gel on a forced-air belt dryer, the water content of the polymer gel being used to control the forced-air belt dryer during or after the drying.