Abstract: PET microfiber can hardly be boiling dyed under atmospheric conditions. In this study, a new disperse atmospheric dyeable polyester (NEDDPET) is synthesized using PTA, IPA, EG and PEG as the basic raw materials. In the process, adding IPA can make the crystalline structure of modified polyester loose, and appropriate adding of PEG can lead to lower glass transition temperature and crystallization temperature, thus realize atmospheric boiling dyeing and anachromasis of PET fiber, while keeping a high level of color fastness. PEG is added to improve the flow properties of the macromolecule and molecular weight of the modified PET, also enhance the fiber’s mechanical performance. The sea-island type composite fiber, which uses NEDDPET as the island, easy hydrolysis degradable polyester (EHDPET) as the sea has a good spinnability, and its mechanical performance is good. A kind of microfiber is made from this compositefiber, the tests show that the fabric knitted of the microfiber can meet the color fastness requirements after dyeing.

Key words: a new disperse dyeable polyester (NEDDPET) ; microfiber; sea-island type composite fiber;color fastness