| 摘要 |
<p>A thermally-stable chloral polymer of formula <FORM:1010091/C3/1> where R is an alkyl radical of 1 to 17 carbon atoms, aryl or substituted aryl, a and c are each integers from 1 to 40 inclusive, b and e are each integers from 0 to 40 inclusive and d is an integer from 1 to 400 inclusive; with the proviso that the sum of a + (b x d) + (c x d) + e is at least 10, the sum of e + (b x d) constituting up to 70 mol. per cent of the polymer composition is prepared by reacting at 80 to 220 DEG C. under acid conditions, a chloral polymeric glycol of number average molecular weight of at least 6000, with from 0.2 to 14 parts per part of the polymer, of an organic acid anhydride, continuing the reaction until the terminal hydroxyls of the polymer chains have been converted to organic ester groups and then recovering a chloral polymeric dicarboxylate of number average molecular weight of at least 6000 and a reaction rate constant for thermal degradation at 255 DEG C. of less than 1.6% per minute. The chloral polymeric glycol may be reacted in a finely-divided solid state with the anhydride in liquid phase. Acetic anhydride is the preferred esterifying compound and a chloral-dichloroacetaldehyde copolymer diacetate preferably containing 40 to 60 mol. per cent dichloroacetaldehyde the specified polymer.</p> |
