Mixed filament yarn of polyester filaments and nylon filaments

Claim 1

A mixed filament yarn, suitable for use as a textile yarn, comprised of spin-oriented polyester filaments and of nylon filaments, wherein said spin-oriented polyester filaments are characterized by an intrinsic viscosity (η) about 0.56 to about 0.68, a minimum tenacity at 7% elongation (T 7 ) of 0.7 g/d, elongation-to-break (E B ) about 60 to about 90%, boil-off shrinkage (S 1 ) less than about 10%, thermal stability as measured by a (S 2 )-value less than about +1%, net shrinkage (S 12 ) less than about 8%, maximum shrinkage tension (ST) less than about 0.3 gpd, density (ρ) about 1.35 to about 1.39 g/cm 3 , and crystal size (CS) about 55 to about 90 Angstroms and also at least about a value in Angstroms, expressed in relationship to the density (ρ), of (250ρ-282.5); and wherein said nylon filaments are characterized by relative viscosity (RV) about 40 to about 80, elongation-to-break (E B ) about 60 to about 90%, boil-off shrinkage (S 1 ) less than about 10%, and dimensional stability as measured by a (ΔL 135-40 C)-value less than 0.