Bottle closure assembly including a polyethylene composition

Abstract

The present disclosure describes bottle closure assemblies which are made at least in part with a polyethylene composition having good processability, good organoleptic properties and good dimensional stability. The bottle closure assembly includes a cap portion, an elongated tether portion, and a retaining means portion. The retaining means portions engages a bottle neck or an upper portion of a bottle. The elongated tether portion connects at least one point on the cap portion to at least one point on the retaining means portion so as to prevent loss of the cap portion from a bottle.

What is claimed is: 
     
         1 . A bottle closure assembly comprising:
 an integrally molded: cap portion, tether portion, and retaining means portion; the cap portion being molded to reversibly engage and cover a bottle opening, the retaining means portion being molded to irreversibly engage a bottle neck or an upper portion of a bottle, and the tether portion being molded to connect at least one point on the cap portion to at least one point on the retaining means portion; wherein the integrally molded: cap portion, tether portion, and retaining means portion are made from a polyethylene composition comprising:   (1) 10 to 70 wt. % of a first ethylene copolymer having a melt index I 2 , of 10 g/10 min or less; and a density of from 0.920 to 0.960 g/cm 3 ; and   (2) 90 to 30 wt. % of a second ethylene copolymer having a melt index I 2 , of at least 50 g/10 min; and a density higher than the density of the first ethylene copolymer, but less than 0.970 g/cm 3 ;   wherein the ratio (SCB1/SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (SCB1) to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB2) is greater than 0.5.   
     
     
         2 . The bottle closure assembly of  claim 1 , wherein the first and second ethylene copolymer comprise polymerized ethylene and at least one polymerized alpha-olefin comonomer, wherein the polymerized ethylene is the majority species. 
     
     
         3 . The bottle closure assembly of  claim 2 , wherein the at least one polymerized alpha-olefin comonomer is 1-octene. 
     
     
         4 . The bottle closure assembly of  claim 1 , wherein the polyethylene composition has a tensile ultimate elongation of at least 600 percent. 
     
     
         5 . The bottle closure assembly of  claim 1 , wherein the polyethylene composition has a tensile ultimate strength of at least 16 MPa. 
     
     
         6 . The bottle closure assembly of  claim 4 , wherein the polyethylene composition has a tensile ultimate strength of at least 16 MPa. 
     
     
         7 . The bottle closure assembly of  claim 1 , wherein the polyethylene composition comprises:
 (1) 10 to 70 wt. % of a first ethylene copolymer having a melt index I 2 , of from 0.1 to 10 g/10 min; a molecular weight distribution M w /M n , of less than 3.0; and a density of from 0.930 to 0.960 g/cm 3 ; and   (2) 90 to 30 wt. % of a second ethylene copolymer having a melt index I 2 , of from 50 to 10,000 g/10 min; a molecular weight distribution M w /M n , of less than 3.0; and a density higher than the density of the first ethylene copolymer, but less than 0.966 g/cm 3 ;   wherein the density of the second ethylene copolymer is less than 0.037 g/cm 3  higher than the density of the first ethylene copolymer; the ratio (SCB1/SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (SCB1) to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0; and   wherein the polyethylene composition has a molecular weight distribution M w /M n , of from 2 to 7; a density of at least 0.950 g/cm 3 ; a high load melt index I 21 , of from 150 to 400 g/10 min; a Z-average molecular weight M Z , of less than 300,000; a melt flow ratio I 21 /I 2 , of from 22 to 50; and a stress exponent of less than 1.40; a stress exponent of less than 1.40; and an ESCR Condition B (100% IGEPAL® CO-630) of at least 3.5 hrs.