| 摘要 |
Polycarbonate containing one urethane group to 1 to 100 carbonate groups are made by (a) reacting 1 mol. of a bis-chloroformate of a dihydric alcohol with 0.5 to 0.95 moles of a dihydric alcohol, and (b) reacting the resulting precondensate with a primary or secondary diamine. Step (a) may be effected by heating the reactants, possibly in the presence of an inert solvent, the hydrogen chloride being removed by passage of an inert gas or being absorbed by an added tertiary amine. Step (b) may be effected in solution or by an inter-facial method. Specified dihydric alcohols are ethylene-, polyethylene-, 1:2-propylene-, polypolypropylene- and 1:2-, 1:3- or 1:4-butylene glycols; also 1:6-hexanediol and 1:4 - cyclohexanedimethanol; and bis-(glycol esters) or polyesters derived from these dihydric alcohol and adipic, maleic, phthalic or terephthalic acid. Specified diamines are ethylene-, hexamethylene- and p-phenylene diamine and piperazine. Uses: threads, films and mouldings. |
