The invention discloses a
polyester elastomer / PET composite
elastic fiber and a preparation method thereof. The preparation method comprises the steps of firstly carrying out reduced-pressure direct esterification on
terephthalic acid, 1,4-
butanediol and double-ended hydroxyl polyether in a certain proportion in the presence of catalysts, carrying out melt polycondensation to obtain a
polyester elastomer, and carrying out a spin-draw-winding one-step process on the prepared
polyester elastomer and PET, so as to obtain the polyester elastomer / PET composite
elastic fiber, wherein the
breaking strength of the polyester elastomer / PET composite
elastic fiber is 2.8cN / dtex-3.56cN / dtex, the elongation at break is 16.9%-30.4%, the
curling degree is 60%-75%, the
curling elasticity rate is 97%-99%, the
capillary water absorption height is 9.7cm / 30min-14.1cm / 30min. Compared with normal composite elastic fibers, the polyester elastomer / PET composite elastic
fiber has relatively excellent elasticity and relatively soft hand feeling, and the fabric capillary suction effect of the polyester elastomer / PET composite elastic
fiber is even higher than those of cotton fabrics; the preparation method is short in production process, high in
spinning speed and low in cost, and the prepared composite elastic
fiber can be directly used in subsequent weaving without being processed into interlaced yarns.