Packaging and wrapping film

A monolayer heat-shrinkable, puncture resistant, biaxially oriented film suitable for use in fabricating bags for packaging food articles, wherein the film comprises an ethylene polymer and has free shrink in both the machine and transverse directions and wherein the ethylene polymer is at least one substantially linear ethylene polymer which is characterized as having:

• (A) a melt flow ratio, I.sub.10 /I.sub.2, .gtoreq.5.63,
• (B) a molecular weight distribution, M.sub.w /M.sub.n, defined by the equation:
• M.sub.w /M.sub.n .ltoreq.(I.sub.10 /I.sub.2)-4.63, and
• (C) a gas extrusion rheology such that the critical shear rate at onset of surface melt fracture for the substantially linear ethylene polymer is at least 50 percent greater than the critical shear rate at the onset of surface melt fracture for a linear olefin polymer, wherein the linear olefin polymer has a homogeneously branched short chain branching distribution and no long chain branching, wherein the substantially linear ethylene polymer and the linear olefin polymer are simultaneously ethylene homopolymers or interpolymers of ethylene and at least one C.sub.3 -C.sub.20 .alpha.-olefin and have essentially the same I.sub.2 and M.sub.w /M.sub.n and wherein the respective critical shear rates of the substantially linear ethylene polymer and the linear olefin polymer are measured at the same melt temperature using a gas extrusion rheometer.

A monolayer heat-shrinkable film comprising at least one substantially linear ethylene polymer which is an ethylene homopolymer or an interpolymer of ethylene and at least one C.sub.3 -C.sub.20 .alpha.-olefin comonomer and wherein the substantially linear ethylene polymer is further characterized as having:

• (A) a melt flow ratio, I.sub.10 /I.sub.2, .gtoreq.5.63,
• (B) a molecular weight distribution, M.sub.w /M.sub.n, defined by the equation:
• M.sub.w /M.sub.n .ltoreq.(I.sub.10 /I.sub.2)-4.63, and
• (C) a gas extrusion rheology such that the critical shear rate at onset of surface melt fracture for the substantially linear ethylene polymer is at least 50 percent greater than the critical shear rate at the onset of surface melt fracture for a linear olefin polymer, wherein the linear olefin polymer has a homogeneously branched short chain branching distribution and no long chain branching, wherein the substantially linear ethylene polymer and the linear olefin polymer are simultaneously ethylene homopolymers or interpolymers of ethylene and at least one C.sub.3 -C.sub.20 .alpha.-olefin and have essentially the same I.sub.2 and M.sub.w /M.sub.n and wherein the respective critical shear rates of the substantially linear ethylene polymer and the linear olefin polymer are measured at the same melt temperature using a gas extrusion rheometer, and
• wherein the film has free shrink in both the machine and transverse directions.

A heat-shrinkable biaxially oriented monolayer film, suitable for use in fabricating bags for packaging food articles, comprising at least one substantially linear ethylene polymer, wherein the substantially linear ethylene polymer is an interpolymer of ethylene and at least one C.sub.3 -C.sub.20 .alpha.-olefin comonomer and is farther characterized as having:

• (A) a melt flow ratio, I.sub.10 /I.sub.2,.gtoreq.5.63,
• (B) a molecular weight distribution, M.sub.w /M.sub.n, defined by the equation:
• M.sub.w /M.sub.n .ltoreq.(I.sub.10 /I.sub.2)-4.63, and
• (C) a gas extrusion rheology such that the critical shear rate at onset of surface melt fracture for the substantially linear ethylene polymer is at least 50 percent greater than the critical shear rate at the onset of surface melt fracture for a linear olefin polymer, wherein the linear olefin polymer has a homogeneously branched short chain branching distribution and no long chain branching, wherein the substantially linear ethylene polymer and the linear olefin polymer are simultaneously ethylene homopolymers or interpolymers of ethylene and at least one C.sub.3 -C.sub.20 .alpha.-olefin and have essentially the same I.sub.2 and M.sub.w /M.sub.n and wherein the respective critical shear rates of the substantially linear ethylene polymer and the linear olefin polymer are measured at the same melt temperature using a gas extrusion rheometer, and
• wherein the film has free shrink in both the machine and transverse directions.