A method for producing a flame retarding polypropylene fiber having both good
flame
retardancy and good fiber strength, and which generates no toxic gas, includes
mixing 0.4% by wt. or more of a hindered amine-based stabilizer and 0.5% by wt.
or more of a phosphoric ester-based flame retardant with a polypropylene resin
having an MPR of 5 to 50 g/10 min, melt-spinning the mixture to form an undrawn
yarn, drafting the yarn at a drafting magnification of 2 to 7 fold and a drafting
temperature of 50 to 100 C., and further thermally setting at 60 to 140 C.
