Multilayer films and methods of making the same
AssigneeExxonMobil Chemical Patents Inc.
InventorsZhi-Yi Shen, Zhen-Yu Zhu, Xiao-Chuan Wang, Ying Zou, Xuanyi Tang
Life of this patent
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Abstract
Disclosed are multilayer films which can provide desired film performance suited for packaging applications favoring cost-effectiveness.
Claims20
A multilayer film, comprising two outer layers and a core layer between the two outer layers, wherein each of the two outer layers comprises 100 wt % of a metallocene polyethylene (mPE), based on total weight of polymer in the outer layer, wherein the mPE comprises a first mPE having a density of about 0.910 g/cm3 to about 0.945 g/cm3, a melt index (MI), I2.16, of about 0.1 g/10 min to about 15 g/10 min, a molecular weight distribution (MWD) of about 1.5 to about 5.5, and a melt index ratio (MIR), I21.6/I2.16, of about 47 to about 100 and the core layer comprises a LLDPE having a MWD of less than 5, a LDPE having a MWD of greater than 4, or a HDPE having a MWD of less than 40, wherein the mPE in each of the two outer layers consists essentially of mPE having a MIR of about 47 to about 100;
- wherein the multilayer film has at least one of the following properties:
- (i) a haze of at least 40% lower, (ii) a clarity of at least 90% higher, (iii) a gloss of at least 40% higher, (iv) a dart impact of up to about 40% higher, (v) a puncture force of up to about 12% higher, and (vi) a tear strength of up to about 5% lower, compared to that of a multilayer film having about 50 wt % of the mPE present in each of outer layers but otherwise identical in terms of density, thickness, and total mPE amount of the film.
A method for making a multilayer film, comprising the steps of:
- (a) preparing two outer layers and a core layer between the two outer layers, wherein each of the two outer layers comprises 100 wt % of a metallocene polyethylene (mPE), based on a total weight of polymer in the outer layer, wherein the mPE comprises a first mPE having a density of about 0.910 g/cm3 to about 0.945 g/cm3, a melt index (MI), I2.16, of about 0.1 g/10 min to about 15 g/10 min, a molecular weight distribution (MWD) of about 1.5 to about 5.5, and a melt index ratio (MIR), I21.6/I2.16, of about 47 to about 100 and the core layer comprises a LLDPE having a MWD of less than 5, a LDPE having a MWD of greater than 4, or a HDPE having a MWD of less than 40, wherein the mPE in each of the two outer layers consists essentially of mPE having a MIR of about 47 to about 100;
- and
- (b) forming a film comprising the layers in step (a);
- wherein the multilayer film has at least one of the following properties:
- (i) a haze of at least 40% lower, (ii) a clarity of at least 90% higher, (iii) a gloss of at least 40% higher, (iv) a dart impact of up to about 40% higher, (v) a puncture force of up to about 12% higher, and (vi) a tear strength of up to about 5% lower, compared to that of a multilayer film having about 50 wt % of the mPE present in each of outer layers but otherwise identical in terms of density, thickness, and total mPE amount of the film.
Dependencies are inferred from the claim text.