End capped polyalkylene carbonates having improved thermal stablity
AssigneeAir Products and Chemicals, Inc.
InventorsDale D. Dixon, Michael E. Ford, Gerald J. Mantell
Life of this patent
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Abstract
Polycarbonates, of the type formed by reacting an aliphatic or cycloaliphatic 1,2-monoepoxide with carbon dioxide and having substantially alternating units of epoxide and carbon dioxide, are improved in thermal stability by reacting the free hydroxyl groups thereon with a hydroxyl reactive sulfur compound. The resulting end capped polycarbonates are useful for producing molded products, films, and packages which are resistant to thermal degradation.
Claims15
A process for improving the thermal stability of a normally solid polyalkylene carbonate having substantially alternating epoxide and carbon dioxide units and having a plurality of free hydroxyl groups represented by the formula:
- ##STR3## wherein:
- R.sub.1 is hydrogen, a halomethyl group, or a hydrocarbyl group having from 1 to 6 carbon atoms;
- R.sub.3 is hydrogen, a halomethyl group, or a hydrocarbyl group having from 1 to 6 carbon atoms;
- R.sub.2 and R.sub.4 are hydrogen or a hydrocarbyl group having from 1 to 6 carbon atoms;
- or
- R.sub.1, r.sub.2, r.sub.3 and R.sub.4 are combined together constituting a carbocyclic ring of from 4 to 7 carbon atoms;
- which comprises end-capping at least a portion of the free hydroxyl groups of said polyalkylene carbonate by reacting said hydroxyl groups with a hydroxyl reactive sulfur compound having the ability to replace the active hydrogen atom on said hydroxyl group for forming an oxygen-sulfur bond.
An end capped polycarbonate having improved thermal stability represented by the formula:
- ##STR4## wherein:
- R.sub.1 is hydrogen, a halomethyl group, or a hydrocarbyl group having from 1 to 6 carbon atoms;
- R.sub.3 is hydrogen, a halomethyl group, or a hydrocarbyl group having from 1 to 6 carbon atoms;
- R.sub.2 and R.sub.4 are hydrogen or a hydrocarbyl group having from 1 to 6 carbon atoms;
- or
- R.sub.1, r.sub.2, r.sub.3 and R.sub.4 are combined together constituting a carbocyclic ring of from 4 to 7 carbon atoms;
- n is a number of from about 250 - 6,500 and
- Z is the residual of a hydrocarbyl radical having from 1 to 20 carbon atoms and substituted derivatives thereof.
Dependencies are inferred from the claim text.