Synthesis And Characterization Of The Cationic Dyeing Modifier Of SIPM

Polyester plays an important role in the synthetic fiber and textile industry because of its, good resistance to chemical, abrasion resistance, non-balling up and bright color, etc., which were based on its isotactic molecular and high crystallinity. However the hygroscopicity and dyeing performance of polyester fabric are poor, which could be improved by adding dyeing modified agent. So far, dimethyl-5-sodium sulfoisophthalate(SIPM) was widely used as dyeing modifier of cationic dyes, for its low production cost and excellent stability to the high temperature of environment. In this thesis, SIPM was synthesized with fuming sulfuric acid, isophthalic acid(IPA), methanol and sodium hydroxide by sulfonation, esterification, neutralization and recrystallization. The optimized process for preparation of SIPM was researched and the determination method of intermediate was established.m-Sulfoisophthalic acid(SIPA) was synthesized with oleum and isophthalic acid, and the results showed that the appropriate molar ratio of SO3(in oleum) to IPA, sulfonation temperature and sulfonation time were 1.2:1, 210 ℃ and 3 h, respectively. The IPA was completely converted into SIPA. The sulfonated product was separated by adding water and washing with hydrochloric acid. The SIPA obtained contain one molecule of crystal water, which the purity and yield were 99% and 89%, repectively. The sulfones(by-product) generated in sulfonation were not found although the the temperature of sulfonation was highly at 210℃.SIPM was synthesized with SIPA and methanol. The appropriate esterification conditions were that the molar ratio of SIPA to methanol, esterification time and the esterification temperature were 1:7, 3h and 70℃, respectively, at which the esterification rate above 99%.The esterifying product was neutralized to pH=7 with 40% NaOH solution at 15-20℃, and the crude SIPM was obtained by filtration. The crude SIPM was recrystallized at 80℃By one-pot synthesis of SIPM at the appropriate reaction condition above, the total yield of SIPM could be reached 80% and the performance satisfied with the standard of industrial product, which the purity, total yield, saponification value, acid value and the content of SO42- in SIPM were 99%, 80%, 377~380 mg KOH·g-1, ≤1.0 mg KOH·g-1,and ≤200ug·g-1, respectively.