Patent GB-1088851-A (GB)
Title: Improvements in or relating to synthetic filament yarns
Inventor: SELWOOD ALAN
IPC: D01D5/22
Filed: 1964-01-10
Abstract: 1,088,851. Crimped synthetic filament yarns. IMPERIAL CHEMICAL INDUSTRIES Ltd. Dec. 29, 1964 [Jan. 10, 1964], No. 1228/64. Heading B5B. [Also in Division D1] A bulky multifilament yarn comprises molecularly oriented polyamide filaments having a random irregular crimp along their length, which crimp persists in the individual filaments when they are pulled out from the yarn, the filaments in the yarn being intermingled to provide a twist-free coherent yarn structure. The yarn preferably consists entirely of wholly polyamide, for example polyhexamethylene adipamide, filaments. At least a proportion of the filaments may be heterofilaments which preferably either are crimped or are potentially crimpable by a heat-relaxing treatment. The heterofilaments preferably consist wholly of polyamide components, for example of at least two of polyhexamethylene adipamide, polyepsilon-caprolactam, polyaminoundecanoic acid and an 80/20 copolymer of polyhexamethylene adipamide and poly-epsilon-caprolactam; however, a minor proportion of the filaments of the yarn or of the polymer components of the heterofilaments may be a polymer other than a polyamide, which polymer may be a polyester, for example polyethylene terephthalate. The components of the heterofilament may exist either in side-by-side or in sheath-core relationship. The yarn may be made by extruding molten polymers consisting of at least a major proportion of a polyamide into filaments which, whilst they are in a substantially amorphous plastic condition, are subjected to the action of a fluid jet at a high velocity to provide a drawing tension in the filaments above the point of application of the jet to attenuate and molecularly orient the filaments and at an angle to the filament path to impart a random irregular crimp to the filaments and to cause the filaments to intermingle to form a coherent yarn structure which is forwarded to a yarn-winding device and formed into a package. At least the polyamide filaments in the yarn are caused to crystallize, crystallization occurring either before the yarn is wound up, for example by treatment with steam, or after being formed into a package, for example under ambient conditions or by a steam or heat treatment; a steam or heat relaxing treatment, when applied to a yarn containing heterofilaments prior to wind-up, additionally may develop in these filaments a uniform helical crimp superposed on the previouslyformed random crimp. The yarn may be formed, see Fig. I, by converging filaments 1, freshly spun through spinneret 2, into a bundle at the throat of aspirating jet 3 within and downstream of which the filaments are acted upon by high velocity fluid, preferably air which may be either at ambient or at an elevated temperature, supplied through inlet 4. The fluid attenuates, molecularly orients and imparts a random irregular crimp to the filaments which also are caused to form a coherent yarn which is forwarded by the fluid issuing from the jet to a centrifugal wind-up system 5 which may be for example a modified Topham box or a device such as is disclosed in Specification 930,546. The aspirating jet, see Fig. II, comprises hollow body portion 10 which is externally threaded at either end to receive cover 12 containing yarn inlet guide 13 and cover 14 containing yarn exhaust guide 15. The bottom and top edges of the inlet and exhaust guides respectively are chamfered to provide an annular fluid injector passageway 16, the high velocity fluid being supplied via fluid inlet pipe 11.