Hinge polymer

Abstract

A polymer suitable for use in a thin film hinge (living hinge) comprising from about 0.1 to about 5 weight % of a C 4-8 comonomer and the balance ethylene, said composition having a density as determined according to ASTM D 792 from about 0.945 to about 0.965 g/cm 3 ; a melt index as determined according to ASTM D1238 (2.16 kg/190° C.) from about 10 to about 20 g/10 min; a weight average molecular weight (Mw) from about 45,000 to about 55,000 g/mol; a polydispersity from about 2.5 to about 3.1 and when molded into a strip having a length of about 13 cm and gross thickness from about 50 to about 70 mil (about 1 to about 2 mm) and completely bent over end to end four times to create a thinned region or crease having a thickness from about 15 to about 30 mil (about 0.3 to about 0.7 mm) tested by bending and releasing the deformed thinned region of the strip through a radius of curvature from about 180 to about 190° about a rounded plate goes through not less than 500 cycles without breaking.

1 - 9 . (canceled) 
     
     
         10 . A living hinge comprising a polyethylene composition, the polyethylene composition comprising from 0.5 to 5 weight % of a C 4-8  comonomer and the balance ethylene; wherein the polyethylene composition has:
 a density as determined according to ASTM D 792 of from 0.945 to 0.965 g/cm 3 ; a melt index as determined according to ASTM D1238 (2.16 kg 190° C.) of from 10 to 20 g/10 min;   a weight average molecular weight (Mw) of from 45,000 to 55,000 g/mol; a polydispersity of from 2.5 to 3.1;   a tensile strength at yield as determined by ASTM D638 (50 mm/min) of from 20 to 30 MPa;   an elongation at brake as determined according to ASTM D638 (50 mm/min) of from 500 to 900%; and   when molded into a strip having a length of 13 cm and a gross thickness from 50 to 70 mil and then completely bent over end to end four times to create a creased strip having a thinned region having a thickness of from 15 to 30 mil, the creased strip will go through not fewer than 500 cycles prior to breaking, when the creased strip is tested in a bending and releasing cycle in which the thinned region of the creased strip is bent and released through a radius of curvature of 180 to 190° C. about a rounded plate until the creased strip breaks.   
     
     
         11 . The hinge according to claim  1 , wherein the creased strip goes through from about 750 to about 2510 bending and releasing cycles before breaking. 
     
     
         12 . The hinge according to claim  1 , wherein the creased strip goes through from about 900 to about 2510 bending and releasing cycles before breaking.