The invention relates to a PBT (
polybutylene terephthalate) modified
fiber, which comprises the following components in percentage by weight: 40-50% of PET (
polyethylene terephthalate), 0-50% of ECDP (easy cationic dyeable poly(
ethylene terephthalate)) and 10-60% of PBT. The invention also relates to a production method of the PBT modified
fiber, which comprises the following steps: mixing and
drying the above components, wherein the
moisture content of each component must be less than 50ppm; fusing the dried components so as to prepare a melt, and extruding the fused raw materials into filaments under the action of a screw extruder; bundling the filaments through a
winding machine and performing back draft in the condition of keeping the
idle speed of the bundling; heating filament tows through a drafting bath and a
steam heating box, and mechanically crimping
yarn sheets through a crimping
machine; realizing a semi-relaxed state by a relaxation heat-setting
machine, ensuring a own modified state and eliminating stress; and
cutting off the
yarn sheets through a
cutting machine as the requirements of customers, delivering to a
packaging machine through a blower and then packaging into a finished product. The
fiber made by the method of the invention has the characteristics of being soft in handfeel, good in resilience force, easy to dye under the normal
temperature and pressure, good in color firmness, strong in
fouling resistance and so on.