Preparation of W/O emulsions

A process for reducing the residual monomer content in a W/O emulsion comprising crosslinked water-swollen addition polymers dispersed therein, said process comprising aftertreating said W/O emulsion with a redox initiator system comprising,

• a) from 0.001 to 5% by weight, based on the total monomer amount used to prepare the polymer,
• a1) of an oxidizing agent:
• R1OOH,
• where R1 is hydrogen, a C1- to C8-alkyl or C6- to C12 aryl group, and/or
• a2) of a compound which in aqueous medium releases hydrogen peroxide, and
• b) from 0.005 to 5% by weight, based on the total monomer amount used to prepare the polymer of a reducing agent,
• b1) which is an α-hydroxy carbonyl compound:
• where, independently of each other,
• R2 is hydrogen or a C1-C12-alkyl group which optionally contains functional groups and/or can be olefinically unsaturated,
• R3 is hydrogen, OH, a C1-C12-alkyl group which optionally contains functional groups and/or can be olefinically unsaturated,
• and R2 and R3 can form a ring structure which can include a heteroatom and/or functional groups and/or can be olefinically unsaturated, and/or
• b2) a compound which in aqueous medium releases an α-hydroxy carbonyl compound, and
• c) catalytic amounts of a polyvalent metal ion which is able to exist in a plurality of valence states.