| abstract |
A composition comprising 80-99 wt.% of a specified anionic polyelectrolyte, 1-20 wt.% of an water-in-oil emulsifier and up to 10 wt.% of water, is new. - The anionic polyelectrolyte is a branched or crosslinked homopolymer of a monomer with either a strong acid or weak acid functional group partially or completely as a salt, a branched or crosslinked copolymer of monomers possessing either a strong acid functional group or a weak acid functional group partially or completely as a salt, a branched or crosslinked copolymer of monomers possessing a strong acid group partially or totally as a salt and monomers possessing a weak acid group partially or totally as a salt and/or one or more neutral monomers. - An INDEPENDENT CLAIM is also included for the preparation of (I), by emulsifying an aqueous solution containing the monomers and optional additives in an oily phase in the presence of one or more water-in-oil emulsifiers, polymerizing by introduction of a free radical initiator and, on conclusion of the reaction, spray drying. - In variants of the procedure one or more oil-in-water emulsifiers may be added before the drying stage and the medium may be concentrated by distillation before the drying stage. Alternatively preparation is by atomizing an auto-invertible inverse latex comprising 15-40 wt.% and preferably 20-25 wt.% oil, 20-50 wt.% water, 2.5-15 wt.% and preferably 4-9 wt.% of emulsifiers of which 20-50 wt.% or more preferably 25-40 wt.% are water-in-oil and 20-70 wt.% or more preferably 25-50 wt.% of the anionic polyelectrolyte. |