IMPROVED METHOD amp; APPARATUS FOR INCREMENTALLY STRETCH- CHING ZERO STRAIN STRETCH LAMINATE WEB IN A NON-UNIFORM MANNER TO IMPART A VARYING DEGREE OF ELASTICITY THERETO

摘要

IMPROVED METHOD AND APPARATUS FOR NON-UNIFORMLY STRETCHING "ZERO STRAIN" STRETCH LAMINATE WEBS (1) TO IMPART ELASTICITY THERETO IN THE DIRECTION OF STRETCHING, AT LEAST UP TO THE POINT OF INITIAL STRETCHING ARE ALSO DISCLOSED. THE "ZERO STRAIN" STRETCH LAMINATE MATERIAL IS FORMED OF AT LEAST TWO PLIES (5, 6) OF MATERIAL WHICH ARE EITHER INTERMITTENTLY OR SUBSTANTIALLY CONTINUOUSLY SECURED TO ONE ANOTHER ALONG AT LEAST A PORTION OF THEIR COEXTENSIVE SURFACES WHILE IN A SUBSTANTIALLY UNTENSIONED ("ZERO STRAIN") CONDITION. ONE OF THE PLIES IS STRETCHABLE AND ELASTOMERIC (4a), WHILE THE SECOND PLY (5) IS ELONGATABLE, BUT NOT NECESSARILY ELASTOMERIC.THE SECOND PLY (5) WILL, UPON STRETCHING OF THE LAMINATE, BE AT LEAST TO A DEGREE PERMANENTLY ELONGATED SO THAT, UPON RELEASE OF THE APPLIED TENSILE FORCES, IT WILL NOT RETURN TO ITS ORIGINAL UNDISTORTED CONFIGURATION.THIS RESULTS IN Z-DIRECTION BULKING OF THE LAMINATE WEB WHEN THE APPLIED TENSION IS RELEASED AS WELL AS ELASTIC EXTENSIBILITY IN THE DIRECTION OF INITIAL STRETCHING, AT LEAST UP TO THE POINT OF INITIAL STRETCHING. (FIG. 2)