Kuraray developed a polypropylene-polyester composite fibre. It is named EPSILON and has a structure in which polypropylene covers polyester that is designed to have a cross section formed into a shape of chrysanthemum. In this structure, when staining, polyester absorbs colorant but polypropylene remains transparent since polypropylene repels colorant. Making use of the polyester’s properties helps reduce cost and difficulty of staining polypropylene. A prime target for supplying the composite fibre will be sports apparel markets, because polypropylene is water-proof and gives a sense of smoothness to a wearer, whilst polyester is able to absorb sweat well.

JCFA News Letter (No.16) September, 2018/Japan Chemical Fibers Association