Synthetic fiber processing agents and synthetic fibers

Abstract

The invention solves the problem of creating a synthetic fiber treatment agent by which tar accumulation can be reduced during application and use for synthetic fibers after long storage periods. The synthetic fiber treatment agent according to the invention is characterized by containing an organic sulfur compound (X) including an organic polysulfide compound (Xi) and an ionic surfactant (Y) including an organic sulfuric acid compound (Yl). Organic polysulfide compounds (XI) are at least one compound chosen from triacylglycerol sulfate (X1-1), monoester of a sulfurized fatty acid (X1-2), a sulfurized fatty acid (X1-3), and olefin sulfate (X1-4). Organic sulfonic acid compounds (VI) have no carbonyl group in their molecules.