Polyalkylenecarbonate compositions with improved thermal stability and method for making same
AssigneeAir Products and Chemicals, Inc.
InventorsDale D. Dixon, Michael E. Ford
Life of this patent
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Abstract
Polyalkylene carbonates are stabilized against oxidative degradation by the inclusion therein of 0.2-10%, preferably 1-5%, of peroxyl-reactive sulphur-containing additive. Such compounds, found to be effective, are 3-t-butyl-4-hydroxy-5-methylphenyl sulfide, diphenyl sulfide, diphenyl sulfoxide, diphenyl sulfone, di-(p-tolyl sulfide) and sulphur.
Claims19
A polyalkylene carbonate composition having improved thermal stability formed by reacting
- (a) a normally solid polycarbonate having substantially alternating epoxide and carbon dioxide units and a plurality of free hydroxyl groups represented by the formula:
- ##STR5## 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 and
- n is the number of repeating units, which ranges from about 250 to 6,500, and
- end-capped modifications thereof with
- (b) 0.2-10%, by weight (based on the weight of polycarbonate to be stabilized) of a sulphur-containing peroxyl radical-reactive compound from the group consisting of metal salts of dithiocarbamic acids;
- aliphatic and aromatic thiols, sulfides, sulfoxides, sulfones, sulfonic acids, and sulfinic acids;
- aliphatic and aromatic disulfides;
- aliphatic and aromatic thioesters and thioamides;
- aliphatic and aromatic thiophosphite esters and thiophosphonates;
- and aliphatic and aromatic phosphotrithionites and phosphotrithronates.
A process for improving the thermal stability of normally solid polycarbonate and end-capped polycarbonate resins, said resins comprising a compound having substantially alternating epoxide and carbon dioxide units and a plurality of free hydroxyl groups represented by the formula:
- ##STR6## 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 and
- n is the number of repeating units, which ranges from about 250 to 6,500, and
- end-capped modifications thereof, said process comprising
- (a) forming a solution of said resin,
- (b) adding thereto 0.2-10%, by weight, (based on the weight of polycarbonate to be stabilized), of a sulphur-containing peroxide radical decomposer compound from the group consisting of metal salts of dithiocarbamic acids;
- aliphatic and aromatic thiols, sulfides, sulfoxides, sulfones, sulfonic acids, and sulfinic acids;
- aliphatic and aromatic disulfides;
- aliphatic and aromatic thioesters and thioamides;
- aliphatic and aromatic thiophosphite esters and thiophosphonates;
- and aliphatic and aromatic phosphotrithionites and phosphotrithionates,
- (c) removing solvent therefrom, and
- (d) subjecting and resultant resin and additive mixture to heat curing conditions.
Dependencies are inferred from the claim text.