Low molecular weight phosphorus-containing polyacrylic acids and use thereof as dispersants
US8735516B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 2, 2012 |
| Grant date | May 27, 2014 |
| Priority date | — |
| Expiry date | May 2, 2032 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08F230/02
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
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 30% by weight and the aqueous hypophosphite solution is added during a total feed time made up of three consecutive feed time spans ΔtI, ΔtII, and ΔtIII, wherein the average feed rate in the second feed time span ΔtII is greater than the average feed rates in the first and third feed time spans ΔtI and ΔtIII.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.