Patent GB-828523-A (GB)
Title: Process for the preparation of polycarbonates
Filed: 1957-09-26
Abstract: Ethylene carbonate is produced as a byproduct in the manufacture of polycarbonates (see Group IV (a)) by heating at above 100 DEG  C. and under superatmospheric pressure a mixture of ethylene oxide, carbon dioxide and an organic compound having at least two active hydrogen atoms in an amount of 0.01-0.20 mols. per mol. of ethylene oxide.  A basic substance is preferably used as catalyst.  The active hydrogen atoms may be in the form of hydroxyl, carboxyl, mercapto, primary or secondary amino or carbamate groups, specified active hydrogen compounds being polyhydric alcohols, polyamines, polymercaptans and alkylolamines.  The compounds may be formed in situ, e.g. by adding water which reacts with the ethylene oxide to form ethylene glycol.ALSO:Polycarbonates of molecular weight 700-5000 are made by reacting at above 100 DEG  C. and under superatmospheric pressure a mixture of an aliphatic or cycloaliphatic epoxide, carbon dioxide and an organic compound having at least 2 active hydrogen atoms in an amount of 0.01-0.20 mols. per mol. of epoxide.  A basic substance is preferably used as catalyst.  Specified epoxides are ethylene and propylene oxide or like epoxide having up to 5 carbon atoms, a mixture of ethylene and propylene oxide, cyclohexene monoepoxide, 4-vinyl cyclohexene monoxide, 4-vinyl cyclohexene dioxide and butadiene diepoxide.  The active-hydrogen atoms may be in the form of hydroxyl, carboxyl, mercapto, primary or secondary amino or carbonate groups, specified active hydrogen compounds being ethylene, diethylene, triethylene, propylene and dipropylene glycols; glycerol, trimethylol ethane, trimethylol propane and pentaerythritol; di-hexamethylene diamines; piperazine; 1,2-ethanedithiol; and ethanolamine and diethanolamine.  These compounds may be formed in situ, e.g. by adding water which reacts with the epoxide to form a dihydric alcohol.  The catalysts may be alkaline reacting hydroxides, carbonates or bicarbonates or aliphatic or heterocyclic tertiary amines.  Reaction may be effected by a bulk or continuous process. Unreacted epoxide and carbon dioxide together with any ethylene carbonate formed as a by-product may be recycled.  The polycarbonates contain terminal hydroxyl groups and may be reacted with polycarboxylic acids (e.g. phthalic, maleic, succinic, fumaric or adipic acids) to form alkyd resins.  They may also be reacted with diisocyanates (e.g. toluene diisocyanate) to form polyurethane rubbers or with diisocyanates, water and, if desired, glycerol to form polyurethane foams (see Group V).  Examples describe the making of polycarbonates from ethylene oxide. Specification 828,524 is referred to.ALSO:Polyurethane foams are made by reacting a diisocyanate with a hydroxy terminated polycarbonate of molecular weight 700-5000 (see Group IV(a)) in the presence of a small quantity of water.  Rigid foams are obtained by including a cross-linking agent, e.g., glycerol, in the reaction mixture.  The foams are suitable for insulating purposes in aircraft, as crash pads and as upholstery cushions.  Specification 828,524 is referred to.