Patent ID: 7188462

Claim:
A process for making a high-strength spun yarn, comprising the steps of: feeding one or more tows of substantially uncrimped continuous filaments of high-modulus material having a tensile modulus exceeding about 20×10 6 psi through a high-speed stretch-breaking apparatus comprising sequentially arranged first, second, and third sets of nip rolls forming first and second stretch-breaking zones, the second set of nip rolls being driven faster than the first set of nip rolls such that the one or more tows are tensioned in the first stretch-breaking zone, the third set of nip rolls being driven faster than the second set of nip rolls such that the one or more tows are further tensioned and caused to break in the second stretch-breaking zone into high-modulus staple fibers having an average length in the range of about 5 to 6 inches; and advancing the high-modulus staple fibers from the stretch-breaking apparatus into a spinning machine without intermediate processing of the staple fibers, the spinning machine forming a high-strength spun yarn from the high-modulus staple fibers.