| 摘要 |
A process for preparing two-phase polymers based on vinyl ester and ethylene in the form of their aqueous polymer dispersions or water-redispersible polymer powders by means of free-radical initiated emulsion or suspension polymerization of one or more vinyl esters of carboxylic acids having 1 to 12 carbon atoms and ethylene as monomers and, if desired, further monomers copolymerizable therewith, in the presence of one or more protective colloids and/or emulsifiers and, if desired, drying the resultant aqueous polymer dispersion, wherein a first polymerization phase takes place at a low ethylene pressure of P less than or equat to 20 bar and in a second polymerization phase raising the pressure to a level of greater than 20 bar to less than 60 bar, the polymer product having an ethylene distribution of less than or equal to 50% by weight of total ethylene from the first polymerization phase and greater than 50% by weight ethylene from the second polymerization phase.
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