초록 ▼

This invention relates to an improved shrink film having balanced properties. In particular, this invention relates to a biaxially oriented polyolefin shrink film made from a particular polymer mixture which includes a first ethylene polymer component having a single differential scanning calorimetr

This invention relates to an improved shrink film having balanced properties. In particular, this invention relates to a biaxially oriented polyolefin shrink film made from a particular polymer mixture which includes a first ethylene polymer component having a single differential scanning calorimetry (DSC) melting peak or a single Analytical Temperature Rising Elution Fractionation (ATREF) peak and a second ethylene polymer component having one or more DSC melting peaks, wherein the density differential between the two component polymers about 0 to about 0.03 g/cc. Improved properties include increased shrink responses, wide orientation windows, higher modulus and high softening temperatures.

대표청구항 ▼

[ We claim:] [1.] A multilayer shrink film having a shrink control layer, the shrink control layer comprising a polymer mixture wherein the polymer mixture has a density in the range of about 0.88 gram/centimeter (g/cc) to about 0.94 g/cc as determined in accordance with A[ D-792 and includes](A) fr

[ We claim:] [1.] A multilayer shrink film having a shrink control layer, the shrink control layer comprising a polymer mixture wherein the polymer mixture has a density in the range of about 0.88 gram/centimeter (g/cc) to about 0.94 g/cc as determined in accordance with A[ D-792 and includes](A) from about 20 to about 80 weight percent, based on the total weight of the polymer mixture, of at least one first ethylene polymer which is a substantially linear ethylene/.alpha.-olefin interpolymer containing at least one C.sub.3 -C.sub.20 .alpha.-olefin, having from about 0.01 to 3 long chain branches per 1000 carbons and characterized as having:i. a short chain branching distribution index (SCBDI) greater than 50 percent,ii. a single melting peak between -30.degree. and 150.degree. C. as determined using differential scanning calorimetry (DSC),iii. a melt flow ratio, I.sub.10 /I.sub.2, equal to or greater than 5.63,iv. a molecular weight distribution, M.sub.w /M.sub.n, defined by the equation: EQU M.sub.w /M.sub.n .ltoreq.(I.sub.10 /I.sub.2)-4.63, andv. a gas extrusion rheology critical shear rate wherein the critical shear rate at the onset of surface melt fracture for the substantially linear ethylene/.alpha.-olefin polymer is at least 50 percent greater than the critical shear rate at the onset of surface melt fracture for a linear ethylene/.alpha.-olefin polymer containing at least one C.sub.3 -C.sub.20 .alpha.-olefin, wherein the linear ethylene/.alpha.-olefin polymer is characterized as having an I.sub.2, and M.sub.w /M.sub.n within ten percent of the substantially linear ethylene/.alpha.-olefin polymer, and wherein the critical shear rates of the substantially linear ethylene/.alpha.-olefin polymer and the linear ethylene/.alpha.-olefin polymer are measured at the same melt temperature using a gas extrusion rheometer, andvi. a density in the range of about 0.87 (g/cc) to about 0.93 g/cc as determined in accordance with A[ D-792, and](B) from about 20 to about 80 weight percent, based on the total weight of the polymer mixture, of at least one second ethylene polymer which is a heterogeneously branched ethylene/.alpha.-olefin ethylene interpolymer containing at least one C.sub.3 -C.sub.20 .alpha.-olefin characterized as having one or more melting peaks as determined using differential scanning calorimetry (DSC) and a density in the range of about 0.89 (g/cc) to about 0.96 g/cc as determined in accordance with A[ D-79,]wherein the density differential between the first and second ethylene polymer components, determined in accordance with A[ D-792, is in the range of from about 0 to about 0.025 g/cc and the density of the first ethylene polymer is equal to or lower than the density of the second ethylene polymer.]