Abstract: A flame resistant and self-extinguishing copolyester composition is made by opolycondensing a dicarboxylic aromatic acid or its diester, a saturated aliphatic diol, a tetrabrominated diol and a sulphonated aromatic compound, preferably in the presence of a phosphor derivative as a complexing and stabilizing agent. Preferably the acid is terephthalic acid and the saturated diol is ethylene or butylene glycol. The viscosity of the copolyester is from 0.3 to 0.6 dl/g and preferably not less than 0.4 or more preferably 0.45 dl/g and its bromine and sulphur contents are 0.1-12% and 0.05-1% by weight respectively, the phosphor, if any, not exceeding 1%. A marked synergic effect of the concurrent presence of bromine and sulphur is evidenced by combustion tests.

Abstract: There is described a family of copolyester compositions for producing heat nd flame resistant fibers, said compositions being prepared by polycondensating (A) an aromatic diacid, (B) a diol, (C) a tetrabrominated diol, (D) a derivative of a polyvalent metal, all said components being hereinbelow defined, the polycondensation process being carried out in several successive stages of copolycondensation of components (A), (B) and (C) until reaching a stable viscosity, then adding component (D), and stopping the reaction before the intrinsic viscosity of the composition decreases below a value proper for subsequent spinning.

Abstract: A thermostable flameproofing agent for copolyesters is prepared by reacting ne mol of a diester of an alkali dicarboxyaryl sulphonate with 1-2 mols of at least one tetrabrominated diol in the presence of a transesterification catalyst chosen in the group consisting of compounds of Zn, Co, Ca, Sn, Ti and Mn. Copolyester compositions adapted for the preparation of formed bodies are prepared by the polycondensation of a dicarboxylic arylic acid or its diesters and a saturated aliphatic diol with said flameproofing agent and up to 1% by weight of a derivative of phosphorus in the presence of a catalyst consisting of Sb.sub.2 O.sub.3 or GeO.sub.2. Said compositions preferably have an intrinsic viscosity not less than 0.40 dl/g before their transformation into formed bodies and not less than 0.35 dl/g after said transformation.

Abstract: New three-component metathesis catalysts prepaed from a tungsten compound, an organic ligand and an organometallic compound of a metal belonging to Group I to IV of the Mendelyeev Periodic System are disclosed. More particularly, the disclosed catalysts are prepared from a tungsten oxychloride, an organic ligand containing a nitrile or ester group, and an organic aluminum compound.