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:
May. 27, 2014
Filed:
Feb. 02, 2012
Howard Roger Dungworth, Brighouse, GB;
David Petty, Bradford, GB;
Bolette Urtel, Bobenheim-Roxheim, DE;
Ruth Wirschem, Mannheim, DE;
Howard Roger Dungworth, Brighouse, GB;
David Petty, Bradford, GB;
Bolette Urtel, Bobenheim-Roxheim, DE;
Ruth Wirschem, Mannheim, DE;
BASF SE, Ludwigshafen, DE;
Abstract
Aqueous solutions of acrylic acid polymers are prepared by polymerization of acrylic acid in a feed operation with a free-radical initiator in the presence of hypophosphite in water as solvent, by a process comprising (i) initially charging water and optionally one or more ethylenically unsaturated comonomers, (ii) continuously adding acrylic acid in acidic, unneutralized form, optionally one or more ethylenically unsaturated comonomers, aqueous free-radical initiator solution and aqueous hypophosphite solution, and (iii) adding a base to the aqueous solution on completion of the acrylic acid feed, wherein a comonomer content does not exceed% by weight and the aqueous hypophosphite solution is added during a total feed time made up of three consecutive feed time spans Δt, Δt, and Δt, wherein the average feed rate in the second feed time span Δtis greater than the average feed rates in the first and third feed time spans Δtand Δt.