Reducing the surface tension of thermoplastic based fibers or filaments, comprises adding at least one copolymer of at least one alpha -olefin and at least one acrylic ester or methacrylic ester of an aliphatic alcohol to the thermoplastic material, and spinning the copolymer by the melt spinning process. Independent claims are also included for: (1) fibers or filaments with a reduced surface tension which are obtainable by melt-spinning of thermoplastic materials, preferably thermoplastic materials of polyamide or polyester, which are additives with at least one copolymer of at least one alpha -olefin and at least one acrylic ester or methacrylic ester of an aliphatic alcohol; and (2) products, preferably fleece, nonwovens, clothes, woven fabrics or knitted fabric obtained from the thermoplastic materials based on fibers or filaments with a reduced surface tension.
