Low-specific-gravity flame-retardant viscose fiber and manufacturing method thereof

The invention discloses a low-specific-gravity flame-retardant viscose fiber and a manufacturing method thereof. The specific gravity of the low-specific-gravity flame-retardant viscose fiber is lowerthan or equal to 1.20g/cm , and a limit oxygen index is larger than or equal to 32.5%. The manufacturing method includes the steps: low-specific-gravity viscose fiber preparation and flame-retardant finishing: (1) preparing acid reaction agent solution and curing agent solution, blending the prepared acid reaction agent solution and curing agent solution and viscose spinning fluid before spinning to solidify nascent fibers through spinning bath, and performing plastifying, drawing, desulfurization and water washing on the nascent fibers to obtain the low-specific-gravity viscose fiber; (2)soaking the low-specific-gravity viscose fiber in flame-retardant soaking liquid containing a flame-retardant agent and a penetrating agent for 3-20 seconds, performing solidifying and oiling on thelow-specific-gravity viscose f