Redox catalyst system for initiating emulsion polymerization

摘要

A redox catalyst system (I) for the radical emulsion polymerisation of ethylenic monomers, consisting of (a) at least one oxidising agent and (b) at least one reducing agent containing an at least bifunctional aldehyde with at least 3 carbon atoms, completely masked as the hydrogen sulphite adduct. Also claimed is (i) production of plastic dispersions by the emulsion polymerisation of vinyl compounds with the aid of (I), and (ii) plastic dispersions obtained by this process, in which masked aldehyde groups capable of crosslinking are bound to the emulsion polymer. Preferably component (a) is an organic hydroperoxide and component (b) is a bis-(alkali hydrogen sulphite) adduct which is soluble or suspendable in water. The preferred system contains (a) tert.-butyl hydroperoxide (t-BHP) and (b) the bis-(sodium bisulphite) adduct of glutaraldehyde or succinaldehyde, with a mole ratio of (oxidising groups in a) to (reducing groups in b) = (1:0.01)-(1:100).