Back to results
US 8,410,222 B2Granted
Method for producing water-absorbing polymer particles
AssigneeBASF SE
InventorsRüdiger Funk, Matthias Weismantel, Sylvia Bertha
Life of this patent
Estimating the term…
Abstract
A process for producing water-absorbing polymer particles, comprising polymerization, drying, comminution, classification and recycling of the undersize obtained in the classification, wherein the recycled undersize is coated with a reducing agent and/or inorganic particles.
Claims13
A process for producing water-absorbing polymer particles by polymerizing a monomer solution or suspension comprising
- a) at least one ethylenically unsaturated monomer bearing an acid group,
- b) at least one crosslinker,
- c) at least one initiator,
- d) optionally one or more ethylenically unsaturated monomer copolymerizable with the monomer specified under a), and
- e) optionally one or more water-soluble polymer,
- comprising the steps of
- i) polymerizing the monomer solution or suspension to give a polymer gel,
- ii) drying the polymer gel,
- iii) comminuting the dried polymer gel, and
- iv) classifying to remove undersize particles,
- the removed undersize particles being recycled at least partially before step ii), wherein at least a portion of the recycled undersize particles is coated with at least one of a reducing agent and inorganic particles, wherein the inorganic particles comprise fumed silica or insoluble salts of phosphoric acid.
8 more elements
Dependencies are inferred from the claim text.