Method of making bulky continuous filament yarns of isotactic polyolefins

Claim 1

THE PROCESS COMPRISING THE STEPS OF FORMING A YARN OF SMOOTH, CONTINUOUS MELT-EXTRUDED FILAMENTS OF A FIBERFORMING POLYMERIC HIGHER ALPHA-OLEFIN CONSISTING PREVAILINGLY OF ISOTACTIC, CRYSTALLIZABLE MACROMOLECULES, HEATING THE YARN AT A TEMPERATURE BETWEEN 20* C. AND 80* C. WHILE STRETCHING IT AT THE MAXIMUN SAFE RATE FOR THE GIVEN TEMPERATURE BETWEEN 20* C. ASND 80* C. BY FEEDING IT THOUGH A STRETCHING ZONE AT THE RATE OF 30 TO 150 METRES/MINUTE AND STRETCHING IT WITH A STRETCH RATIO BETWEEN 1:2.5 AND 1:5.5 TO INTRODUCE INTO THE INDIVIDUAL FILAMENTS OF THE YARN INTERNAL STRAINS WHICH ARE IREEGULARLY DISTRIBUTED ALONG THE LENGTHS OF THE INDIVIDUAL FILAMENTS, ABURPTLY INTRODUCING THE YARN OF STRETCHES, IRREGULARLY STRAINED FILAMENTS INTO A MEDIUM IN WHICH IT IS HEATED RAPIDLY, WITHOUT THE APPLICATION OF TENSION THERETO, TO A TEMPERATURE BETWEEN 50* C. AND THE , MELTING POINT OF THE POLYMERIC ALPHA-OLEFIN AND SELECTED IN DEPENDANCE OF THE STRETCHING TEMPERATURE TO RELEASE THE STRAINS INTRODUCED INTO THE FILAMENTS BY THE STRETCHING, THE RELEASE OF THE IRREGULARLY-DISTRIBUTED INTERNAL STRAINS RFESULTING IN THE FORMATION OF CRIMPS IN THE INDIVIDUAL FILAMENTS WHICH CRIMPS ARE IRREGULARLY DISTRIBUTED ALONG THE LENGTH OF THE FILAMENTS WITH THEIR LOOPS DISPOSED IN DIFFERNET PLANES, AND THE CRIMPS IN THE DIFFERENT FILAMENTS SERVING TO SEPARATE THE INDIVIDUAL FILAMENTS OF THE YARN FROM EACH OTHER AND PROVIDE AIR SPACES BETWEEN THE CRIMPS WHICH CONTRIBUTE TO THE BULKINESS, LIGHTNESS AND INSULTING CAPACITY OF THE YARN, THE BULKY YARN BEING FURTHER CHARACTERIZED IN THAT THE ORIENTATION OF THE CRYSTALLITES OF THE POLYMERIC ALPHAOLEFIN RESULTING FROM STRETCHING OF THE SMOOTH CONTINUOUS FILAMENTS IS SUBSTANTIALLY RETAINED IN THE CRIMPED FILAMENTS, AND THE YARN CONSISTING OF THE CRIMPED FILAMENTS HAS SUBSTANTIALLY THE SAME TENSILE STRENGTH AS THE STRENGTH AND ORIENTED YARN PRIOR TO THE RELAXATION OF THE STRAINS AND CRIMPING.