Production of a water-absorbing resin to which a particulate additive is admixed

US7786211B2 · kind B2 · utility

Assignee

• BASF SE

Inventors

• Uwe Stueven · Bad Soden, DE
• Rüdiger Funk · Niedernhausen, DE
• Matthias Weismantel · Bad Orb, DE
• Thomas Daniel · Waldsee, DE
• Annemarie Hillebrecht · Bad Reichenhall, DE
• Dominicus van Esbroeck · Nanjing, CN
• Karl J. Possemiers · Schilde, BE

Key dates

• Filing date: Dec 28, 2006
• Grant date: Aug 31, 2010
• Expiry date: Apr 29, 2027

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08F222/102
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

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 wate…