Abstract: A plastic container having improved properties as a barrier against gases and water vapor made from a thermoplastic resin composition comprising (A) an aromatic polyester carbonate composed of an aromatic dicarboxylic acid moiety, an aromatic dihydroxy compound moiety and a carbonate moiety and (B) a polyalkylene terephthalate and/or a polyalkylene oxybenzoate in a ratio of 100 parts by weight of said aromatic polyester carbonate to 100 parts by weight or less of said polyalkylene terephthalate and/or polyalkylene oxybenzoate.

Abstract: A process for producing an aromatic polyester composition, which is characterized in that in producing an aromatic polyester represented by the general formula A, ##STR1## (wherein X is an alkylene group having 1 to 4 carbon atoms, --O--, --SO.sub.2 --, --S--, or --CO--; m and n are each 0 or 1; the ratio of d to e is in the range of from 1:1 to 10:1; the ratio of e to f is in the range of from 9:10 to 10:9; and the substituents attached to the benzene ring are in para or meta position to one another), the polymerization is carried out by the method of bulk polymerization, using substantially no solvent, and in the presence of at least one polymer selected from the group consisting of polyalkylene terephthalates, polyphenylene sulfides, aromatic polysulfones, and aromatic polyesters represented by the general formula B, ##STR2## wherein (p+q) is in the range of from 10 to 100 and p/(p+q).gtoreq.0.8.

Abstract: In a process for producing an aromatic polyester by reacting under application of heat (A) an aromatic dicarboxylic acid and/or an ester-forming derivative thereof, (B) an aromatic hydroxycarboxylic acid and/or an ester-forming derivative thereof, and (C) a dihydroxy aromatic compound produced by the method of alkali fusion and containing 4,4'-dihydroxydiphenyl as major constituent and/or an ester-forming derivative of said dihydroxy aromatic compound, the improvement which comprises employing as said 4,4'-dihydroxydiphenyl, a 4,4'-dihydroxydiphenyl of such a quality that a solution of 1 part by weight of it dissolved in 100 parts by weight of a mixture comprising methanol and water in a weight ratio of 70:30 will show a pH of 6.6 to 7.4. The polyester produced by the improved process shows little discoloration and is excellent in thermal resistance and mechanical properties.