Film layers made from ethylene polymer blends
Film layers made from formulated ethylene polymer compositions are disclosed. Film layers made from such formulated compositions have surprisingly good heat seal properties, and an especially good reduction in heat seal initiation temperature. The ethylene polymer compositions have at least one homogeneously branched ethylene/alpha-olefin interpolymer and at least one homogeneously or heterogeneously branched ethylene polymer which has a lower melt index than the first mentioned component. The first homogeneously branched ethylene/alpha-olefin interpolymer has a melt index higher than that of the formulated composition.
1. A film layer made from a polymer composition, wherein the composition comprises
(A) from 10 percent (by weight of the total composition) to 95 percent (by weight of the total composition) of at least one homogeneously branched ethylene/alpha-olefin interpolymer having:
(i) a density from 0.86 grams/cubic centimeter (g/cm 3 ) to 0.92 g/cm 3 ,
(ii) a molecular weight distribution (Mw/Mn) from 1.8 to 2.8,
(iii)a melt index (I 2 ) from 0.2 grams/10 minutes (g/10 min) to 200 g/10 mm,
(iv) substantially no high density fraction; and
(B) from 5 percent (by weight of the total composition) to 90 percent (by weight of the total composition) of at least one heterogeneously branched ethylene polymer having a density from 0.88 g/cm 3 to 0.945 g/cm 3 ;
wherein the polymer composition has a melt index which is from 0.5 grams/10 minutes to 30 grams/10 minutes and which is lower than the melt index of component (A).
2. The film layer of claim 1 having a heat seal initiation temperature of no greater than 105° C.
3. The film layer of claim 1 wherein the homogeneously branched ethylene/alpha olefin polymer of component (A) is an interpolymer of ethylene with at least one C 3 -C 20 alpha-olefin.
4. The film layer of claim 1 wherein the heterogeneously branched ethylene polymer is a copolymer of ethylene and a C 3 -C 20 alpha-olefin.
5. The film layer of claim 1 wherein the heterogeneously branched ethylene polymer is a copolymer of ethylene and 1-octene.
6. The film layer of claim 1 wherein (B) has a density higher than the density of the composition.
7. The film of claim 1 , wherein the composition comprises more than 40 percent (by weight of the total composition) of Component (A).