A flameproof linear polyester is described containing, copolymerised in the molecule, a phosphorus compound of formula:
where R is a hydrogen atom, an alkyl group with 1 to 4 carbon atoms or a hydroxyalkyl group, and R' is a hydrogen atom, a hydroxyalkyl group or the group -(CH2CH20)nH, where n varies from 1 to 4. Said linear polyester is prepared by firstly forming a low molecular weight precondensate from a dicarboxylic aromatic acid (or a relative lower alkyl diester) and an alkylene glycol, and then polycondensing in the presence of said phosphorus compound, in such a quantity as to obtain a content of phosphorus (expressed as the metal) in the linear polyester of between 0.4 and 0.8% by weight. The linear polyester thus obtained can be formed into articles such as fibres, film, sheets and other articles which, besides being flameproof, possess improved dyeing characteristics. A process is also described for preparing the phosphorus compounds corresponding to the aforesaid general formula, where R is hydrogen or an alkyl group containing 1 to 4 carbon atoms, and R' is hydrogen. Said phosphorus compounds are prepared by reacting phenylphosphinic acid or ester with paraformaldehyde, at a temperature of between 60 and 150°C.
所述阻燃线性聚酯分子中含有共聚的式
磷化合物:
其中 R 是氢原子、含 1 至 4 个碳原子的烷基或羟烷基,R'是氢原子、羟烷基或基团 -(CH2CH20)nH,其中 n 为 1 至 4。所述线性聚酯的制备方法是:首先由二
羧酸芳香族化合物(或相对低级的烷基二酯)和亚烷基二醇形成低分子量的预缩合物,然后在所述
磷化合物存在下进行缩聚,缩聚量为线性聚酯中
磷(以
金属表示)含量的 0.4%至 0.8%(按重量计)。由此获得的线性聚酯可以制成纤维、薄膜、片材等物品,这些物品除了具有阻燃性外,还具有更好的染色特性。还描述了制备上述通式对应的
磷化合物的工艺,其中 R 是氢或含有 1 至 4 个碳原子的烷基,R'是氢。上述
磷化合物是通过
苯基膦酸或酯与多
聚甲醛在 60 至 150°C 的温度下反应制备的。