Degradable polyester fiber and its preparation method

A method for preparing a degradable polyester fiber, comprising:

• cooling a polyethylene terephthalate (PET) melt by ring-blowing after extruded from a trilobal spinneret hole on a spinneret;
• then manufacturing a fully drawn yarn (FDY) according to an FDY process with the PET melt;
• and performing a relaxation heat treatment to obtain the degradable polyester fiber;
• wherein the PET melt disperses with a doped ZrO2 powder, the doped ZrO2 powder is obtained through a process of evenly mixing a Mx+ solution and a Zr4+ solution at first, then dripping in a precipitant until a pH value is 9-10 to obtain a precipitate, and finally calcining the precipitate;
• wherein Mx+ in the Mx+ solution is more than one ion selected from the group consisting of Mg2+, Li+, and Zn2+;
• wherein a ratio of angles between center lines of three leaves from a same trilobal spinneret hole is 1.0:(1.5-3.1):(1.5-3.1);
• wherein the three leaves from the same trilobal spinneret hole comprise a first leaf, a second leaf, and a third leave;
• wherein a ratio of lengths of the first leaf and the second leaf forming a smallest angle to a length of the third leaf from the same trilobal spinneret hole is 3:3:2;
• wherein a ratio of a length to a width of the third leaf that is a shortest leaf of the three leaves of the same trilobal spinneret hole is (1.5-2):1 with of other two leaves of the same trilobal spinneret hole having same widths;
• wherein shapes and sizes of three leaves from different trilobal spinneret holes are the same;
• wherein all the trilobal spinneret holes are distributed in concentric circles with a center line of a leaf opposite to the smallest angle in each trilobal spinneret hole passing through a center of the concentric circles and pointing away from the center of the concentric circles;
• wherein the FDY process comprises a cooling temperature of 20-25° C. and a cooling wind speed of 1.80-2.30 m/s.