| 摘要 |
A process for the polymerization of ethylenically unsaturated monomers wherein a solid, monomer-soluble, free-radical forming compound is used as initiator. The initiator is charged to the polymerization system in the form of an aqueous dispersion comprising an emulsifier combination which consists of an ethoxylated nonionic emulsifier with an HLB-value above 15, which does not contain cyclic inner ether bonds, and a non-ethoxylated nonionic emulsifier with an HLB-value below 9. The emulsifier combination has a resulting HLB-value within the interval 11-17 and the combination is used in an amount of at least 1% by weight based on the initiator. Polymerizates produced according to the method have good electric insulation properties. A means suitable for the polymerization of ethylenically unsaturated monomers consists of an aqueous dispersion of a free-radical forming initiator, which dispersion comprises the mentioned emulsifier combination in an amount of at least 1 percent by weight, based on the initiator. The dispersion preferably also contains a protrective colloid such as polyvinyl alcohol. The dispersions have good stability and are easy to handle. |
