双酰亚胺型均苯四甲酸及复合酸镧盐的合成与应用

Synthesis and application of composite lanthanum salt of pyromellitic di-imido tetra-carboxylic and stearic acids

采用水热法制备了4,4'-亚甲基-二苯基-二-(1″,2″)-酰亚胺-二-(4″,5″)-苯二甲酸酐(简称酰亚胺四酸酐)以及双硬脂酸单4,4'-亚甲基-二苯基-二-(1″,2″)-酰亚胺-二-(4″,5″)-苯二甲酸二镧(简称复合酸镧盐La-1),应用红外光谱与热失重法对其结构进行表征,并将La-1应用于聚酰胺66(PA 66)以改善PA 66热氧化稳定性,且与硬脂酸镧(La-2)、均苯四甲酸镧(La-3)、双硬脂酸单均苯四甲酸二镧(La-4)进行比较。结果表明:通过正交实验得出,酰亚胺四酸酐合成的最优反应条件为酰亚胺化反应温度135℃,时间5 h,二甲苯与产物水质量比6∶1,均苯四甲酸酐(PMDA)与4,4'-二氨基二苯甲烷(DDM)摩尔比2.3∶1.0;傅里叶变换红外光谱表征所合成的酰亚胺四酸酐和La-1为目标产物;La-3的热分解温度大于550℃,高于PA 66的热分解温度,La-1,La-2,La-3的热稳定性均弱于纯PA 66;La-3,La-4对PA 66的抗黄变性效果比La-1,La-2的要好,这是由于硬脂酸长链热稳定性差及芳香酸镧中的邻苯二甲酸结构中残存羟基量对PA 66热氧化稳定性造成影响的缘故。

4,4＇-methylene-biphenyl-di-（ 1″,2″）-imido-bi-（ 4″,5″）-phthalic anhydride（ referred to as imido teracarboxylic dianhydride） and bi-lanthanum bi-stearate and 4,4＇-methylene biphenyl-di-（ 1″,2″）-imido-bi-（ 4″,5″）-phthalate（ referred to as lanthanum fatty aromatic carboxylates La-1） were prepared by hydro-thermal method. The structure of the two compounds was characterized by infrared spectrometry and thermogravimetry. La-1 was used to improve the thermo-oxidative stability of polyamide 66（ PA 66） and was compared with lanthanum stearate（ La-2）,pyromellitic lanthanum（ La-3）,monopyromellitic lanthanum bistearate（ La-4）. The results showed that the synthesis conditions of imido teracarboxylic dianhydride were optimized by orthogonal experiment as followed： imidization reaction temperature 135 ℃ and time 5 h,xylene-and-product water ratio of 6∶1,mole ratio of pyromellitic dianhydride（ PMDA） and 4,4＇-diaminodiphenylmethane（ DDM） of 2. 3 ∶1. 0; the target products were proved to be imido teracarboxylic dianhydride and La-1 by Fourier transform infrared spectrometry; the thermal decomposition temperature of La-3 was above 550 ℃,higher than that of PA 66; the thermal stability of La-1,La-2 and La-3 was all lower than that of PA 66; as compared with La-1 and La-2,La-3 and La-4 contributed higher yellowing resistance to PA 66,which was attributed to the poor thermal stability of the long molecular chain of stearate and the impact of residual carboxy group in o-phthalic acid structure of aromatic lanthanum on the thermo-oxidative stability of PA 66.