Preparation of water-absorbing resin, useful in sanitary articles e.g. diapers, comprises polymerizing a reaction mixture comprising hydrophilic monomer and cross-linker

摘要

Preparation of water-absorbing resin by polymerization of a reaction mixture comprising at least one hydrophilic monomer and optionally at least one cross-linker, comprises mixing at least a first portion of a particulate additive in the reaction mixture, before the reaction mixture reaches a retention time of 40% of the total retention time in the reactor; and mixing at least a second portion of a particulate additive in the reaction mixture, when the reaction mixture reaches a retention time of 45% or more of the total retention time in the reactor. Preparation of water-absorbing resin by polymerization of a reaction mixture comprising at least one hydrophilic monomer and optionally at least one cross-linker, in a reactor, comprises mixing at least a first portion of a particulate additive in the reaction mixture, before the reaction mixture reaches a retention time of 40% of the total retention time in the reactor; and mixing at least a second portion of a particulate additive in the reaction mixture, when the reaction mixture reaches a retention time of 45% or more of the total retention time in the reactor, where: the additive is a water-adsorbing resin powder and/or filler; the total solid content of the monomer and additive is 30-60 wt.%; the amount of the additive is 5-50 wt.%, based on the monomer; and the weight ratio of the first fraction to the second fraction of the additive is 10:10-1:5.