| 摘要 |
Polymer dispersion (PD) with a minimum film-forming temperature (MFT) of 0-40 degrees C, obtained by emulsion polymerisation in stages using different monomer mixtures. The monomer composition (I) for stage 1 comprises 50-68.5 wt% soft monomers (A) which form homopolymers with Tg below 0 degrees C, 30-50 wt% hard monomers (B) which form homopolymers with Tg above 65 degrees C, 0.5-5 wt% alpha , beta -unsaturated carboxylic acid or amide comonomers (C), 1-75 wt% unsaturated monomers (D) containing keto groups and 0-10 wt% other unsaturated monomers (E) with no nitrogen atoms. The composition (II) for stage 2 comprises 5-45 wt% monomers (A) as above, 65-96 wt% (B), 0-4 wt% (C), 0-5 wt% (D) and 0-10 wt% (E), and the wt. ratio (I):(II) = (50:50)-(75:25). Also claimed is a process for the production of PD by emulsion polymerisation, in which compositions (I) and (II) are emulsified and polymerised one after the other in aqueous phase at 60-95 degrees C in presence of emulsifiers, initiators and optionally pro tective colloids. |
