Process for the preparation of aliphatic diol polycarbonates
AssigneeSociete Nationale des Poudres et Explosifs
InventorsJean-Pierre G. Senet, Julien C. Deweerdt
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Abstract
Hydroxy-telechelating oligomers of number average molecular weight 250 to 2,500 and containing carbonate groups, are prepared by first polycondensing a bis-chloroformate with a diol at a temperature below 150.degree.C and at a moderately reduced pressure while flushing the reaction mixture with an inert anhydrous gas, and then the oligomers formed are dissolved in a volatile, water-immiscible organic solvent and the solution washed with an aqueous base solution. In this way, oligomers may be prepared which have a low or zero sensitivity to water, are non-acidic and relatively inexpensive.
Claims16
A process for preparing telechelating oligomers having two terminal hydroxyl groups of numerical average molecular weight between 250 and 2500, which possess carbonate groups distributed through the macromolecular chain, with the repeating unit of structure ##EQU13## in which each of A and B is branched or straight chain bivalent aliphatic hydrocarbyl or cycloaliphatic hydrocarbyl radical, unsubstituted or substituted by aromatic, halogen or phosphorus-containing groups, or is a branched or straight chain bivalent aliphatic hydrocarbyl or cycloaliphatic hydrocarbyl radical additionally containing at least a functional bridge selected from the group consisting of ether, thioether and ester radicals and A and B are the same or different, which consists of reacting a monomer which is a bis-chloroformate of formula ##EQU14## in which B is as defined hereinabove with an excess of a monomer diol of the formula
- HO -- A -- OH
- in which A is as defined hereinabove, in three sequential steps:
- 1. introducing one of said monomers into the other over a period of 20 minutes up to 4 hours under reduced pressure of 1-10 cm of mercury at a temperature of 20.degree.-80.degree.C while flushing the reaction mixture with a gentle stream of an inert anhydrous gas, and
- 2. polycondensing the bis-chloroformate with the diol at a temperature below 150.degree.C, under reduced pressure of 1-10 cm of mercury for a period of time between 1.5 hours and 7 hours;
- 3. and purifying the crude oligomers formed.
Dependencies are inferred from the claim text.