| 摘要 |
Production of moulding compositions with reduced yellowing tendency under thermal stress involves producing an imidised methacrylate polymer with units of formula (I) by a conventional imidisation reaction in a reaction extruder. After imidisation, the polymer is treated with 0.005-1 wt.% reducing inorganic phosphorus compound(s) (II) selected from phosphinic and phosphonic acids and their alkali(ne earth) metal, aluminium and ammonium salts, in which the ammonium ion may have upto 4 1-4 carbon (C) alkyl and/or 5-6 C cycloalkyl substituents. R1, R2 = hydrogen (H) or methyl (Me); R3 = H, 1-18 C alkyl, 5-8 C cycloalkyl, 6-10 C aryl or 6-10 C aryl-(1-4 C)-alkyl, optionally mono- to tri-substituted by 1-4 C alkyl, 1-4 C alkoxy and halogen. Also claimed are the mouldings prepared using the claimed process. Preferably, (II) is added in aqueous solution. It is mixed with the particulate polymer or added to a polymer melt freed from volatiles, especially continuously in a degassing extruder following the reaction extruder. |
