Preparation of finely divided polymer powders

US5795926A · kind A · utility

Assignee

• BASF SE

Inventors

• Manfred Niessner · Schifferstadt, DE
• Norbert Grund · Ludwigshafen, DE
• Wilfried Heide · Freinsheim, DE
• Heinrich Hartmann · Schifferstadt, DE

Key dates

• Filing date: Nov 21, 1991
• Grant date: Aug 18, 1998
• Expiry date: Nov 21, 2011

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/2982
• WIPO field: Environmental technology
• WIPO sector: Chemistry

Abstract

A process is described for the preparation of finely divided polymer powders by polymerizing water-soluble monomers in the aqueous phase of a water-in-oil emulsion in the presence of water-in-oil emulsifiers and polymerization initiators, removing the water from the resultant water-in-oil polymer suspension by azeotropic distillation, and isolating the suspended, finely divided polymer powder, either the polymerization of the water-soluble monomers being carried out in the presence of from 0.1 to 10% by weight, based on the monomers employed in the polymerization, of protective colloids, or the protective colloids being added to the water-in-oil polymer suspension after the polymerization is complete. The polymerization is preferably carried out in the presence of surfactant. The finely divided pulverulent polymers are used as flocculants or thickeners for aqueous systems.