The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 08, 2013
Filed:
Aug. 23, 2010
Uwe Stueven, Bad Soden, DE;
Rüdiger Funk, Niedernhausen, DE;
Matthias Weismantel, Jossgrund-Oberndorf, DE;
Thomas Daniel, Waldsee, DE;
Annemarie Hillebrecht, Künzell, DE;
Dominicus Van Esbroeck, Nanjing, CN;
Karl J. Possemiers, Gravenwezel, BE;
Uwe Stueven, Bad Soden, DE;
Rüdiger Funk, Niedernhausen, DE;
Matthias Weismantel, Jossgrund-Oberndorf, DE;
Thomas Daniel, Waldsee, DE;
Annemarie Hillebrecht, Künzell, DE;
Dominicus van Esbroeck, Nanjing, CN;
Karl J. Possemiers, Gravenwezel, BE;
BASF SE, Ludwigshafen, DE;
Abstract
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.