Multilayer film including recycled polymer

Abstract

Disclosed herein are multilayer films. The multilayer films according to embodiments disclosed herein comprise a recycled LLDPE composition and can have balanced tear strength and impact strength comparable to monolayer films of virgin LLDPE with a similar gauge. The multilayer films include internal and two face layers where the layers comprise a recycled LLDPE composition to provide the beneficial properties.

Description

[0001] MULTILAYER FILM INCLUDING RECYCLED POLYMER

[0002] FIELD

[0003] Embodiments described herein relate to multilayer polyethylene films comprising recycled polyethylene.

[0004] INTRODUCTION

[0005] A challenge faced by the polymer industry is the environmental impact of its products, especially the accumulation of plastic waste in landfills and oceans. For example, plastic polymer waste poses a threat to ecosystems. There is a growing demand from society and regulators for more sustainable solutions that reduce plastic polymer waste with an increase in plastic recycling and incorporation of recycled polymers. This demand centers on the idea that recycling plastic and incorporating polymers back into products can save resources and energy.

[0006] Recycling polymers is not an easy task. Recycling polymers and incorporating post recycled polymers into new products is likewise not an easy task. Waste is often contaminated, degraded, mixed, or incompatible with other types of materials. Moreover, post recycled polymers have different properties such as mechanical and optical properties than virgin polymers, which limits their applications and market value. Therefore, there is a need for innovative technologies that can enhance the compatibility and blendability with recycled polymers with virgin polymer and increase the amount of recycled polymers without compromising performance.

[0007] One application of recycled polymers is in the production of monolayer films suitable for use as trash bags. Trash bags are one of the largest segments of the film market, and they have a short lifespan and a low recycling rate. Trash bags can be formed with recycled polyethylene (e.g., “pre-consumer recycled” or “post-consumer recycled” (PCR)). Incorporating recycled polyethylene into trash bag films can reduce the environmental footprint of this product and create a circular economy. However, recycled polymers alone may not meet the requirements for trash bag films, such as strength, toughness, puncture resistance, sealability and appearance. Accordingly, it is necessary to find ways to improve the properties of recycled polymers and films.

[0008] SUMMARY

[0009] A first aspect of this invention is a multilayer film. A multilayer film according to embodiments disclosed herein comprises two face layers and at least one internal layer, wherein the film comprises: a) at least 20 volume percent of one or more layers, called “T-Layers”, that comprise a first LLDPE polymer, called “T-LLDPE”, having a melt index of 0.2 dg / min to 4.0 dg / min and an MWCDI less than -1.0, and wherein at least one face layer is a T-Layer; b) at least 5 volume percent of one or more layers, called “I-Layers”, that comprise a second LLDPE polymer, called “I-LLDPE”, having a melt index of 0.4 dg / min to 4.0 dg / min and an MWCDI greater than 1.0; and c) at least 10 volume percent of one or more layers, called “R-Layers”, that comprise a LLDPE composition, called “R-LLDPE”, that comprises recycled LLDPE polymers; d) optionally, one or more layers, called “B-Layers”, that comprise a third LLDPE polymer, called “B- LLDPE”, having a melt index of 0.4 dg / min to 4.0 dg / min and an MWCDI from -1.0 to 1.0, wherein the multilayer fdm comprises at least 10 weight percent recycled LLDPE polymers, and wherein volume percent is based on the total volume of the film.

[0010] A second aspect of the present invention is a bag that comprises the multilayer film in the first aspect of the invention.

[0011] DETAILED DESCRIPTION

[0012] This invention relates to a multilayer film comprising LLDPE. The multilayer film comprises at least 3 layers. In some embodiments, the multilayer film comprises at least 4 layers, or at least 5 layers, or at least 6 layers, or at least 7 layers. In some embodiments, the multilayer film comprises at most 15 layers, or at most 13 layers, or at most 11 layers, or at most 10 layers, or at most 9 layers, or at most 8 layers, or at most 7 layers. The two outermost layers, located on the outside faces of the multilayer film, are called face layers. The other layers of the multilayer film, located between the face layers, are called internal layers.

[0013] Layers of the multilayer film comprise LLDPE polymers (referred herein in specific instances as “a first LLDPE polymer,” “a second LLDPE polymer,” and “a third LLDPE polymer”). The LLDPE polymer is a copolymer in which a majority of repeating units are derived from ethylene monomer and a minority of repeating units are derived from a-olefin comonomers. Examples of suitable a-olefins include those comprising from 3 to 20 carbon atoms (C3-C20). In some embodiments, the a-olefin comonomer comprises at least 4 carbon atoms, or at least 5 carbon atoms, or at least 6 carbon atoms. In some embodiments, the a-olefin comonomer comprises at most 15 carbon atoms, or at most 12 carbon atoms, or at most 10 carbon atoms, or at most 8 carbon atoms. In some embodiments, the alpha-olefin is selected from the group consisting of propylene, 1-butene, 1-pentene, 1 -hexene, 4-methyl-l -pentene, 1-heptene, 1- octene, 1 -nonene and 1 -decene. In some embodiments, the alpha-olefin is selected from the group consisting of 1-butene, 1-hexene, and 1-octene. In some embodiments, the alpha-olefin is either 1-hexene or 1-octene.

[0014] In some embodiments, the LLDPE polymers comprise at least 2 mole percent repeating units derived from comonomers, or at least 3 mole percent, or at least 4 mole percent, or at least 5 mole percent. In some embodiments, LLDPE polymers comprise at most 20 mole percent repeating units derived from comonomers, or at most 15 weight percent, or at most 12 mole percent, or at most 10 mole percent, or at most 8 mole percent.

[0015] The LLDPE polymers may be blended with other polymers. The LLDPE polymers may be blended with two or more LLDPE polymers. The LLDPE polymers may be blended with one or more other polyethylene polymers such as low density polyethylene or high-density polyethylene. The LLDPE polymer may comprise additives, antioxidants, stabilizer, slip agents, or other compositions that are routinely used and known to those skilled in the art for making LLDPE polymers.

[0016] Polymer blends can be made by known processes, such as by coextruding homogenous mixtures of the polymers through a single extruder. Some polymers, such as other polyethylenes, are compatible with LLDPE and form homogeneous blends readily. Other polymers, such as polar polymers, are incompatible with LLDPE and require a compatibilizer to form homogeneous blends. Compatibilizers are commercially available under the RETAIN™ and PUS AB OND™ trademarks.

[0017] The densities, molecular weights, and MWCDI of LLDPE polymers that are used in specific layers of the multilayer films are discussed below, in connection with each specific layer. In some embodiments, specific layers of the multilayer films consist essentially of the LLDPE polymer described for that layer, meaning that layer contains no other polymer composition in a quantity high enough to materially change the properties of the layer.

[0018] In some embodiments, the LLDPE polymers are virgin LLDPE polymers. Suitable virgin LLDPE polymers for use in the multilayer films are commercially available, such as under the DOW™ LLDPE, DOWLEX™, TUFLIN™, ATTANE™ and INNATE™ trademarks. Virgin LLDPEs can also be made by known processes, such as solution, slurry and / or gas-phase polymerization of ethylene monomer and comonomers in the presence of Ziegler-Natta catalysts, metallocene catalysts or other single site catalysts. All of these processes are well-known and described in many patents and other publications.

[0019] The multilayer film comprises a recycled LLDPE composition, called “R-LLDPE.” Suitable recycled LLDPE compositions for use in the multilayer film are commercially available under the name REVOLOOP™ and commercially available from The Dow Chemical Company (Midland, MI). Recycled LLDPE compositions can also be made by known processes such as: (1) separating polyethylene (PE) polymers having desired properties from a recycle waste stream; (2) washing the separated PE polymers; (3) grinding the separated PE polymers; and (4) optionally pelletizing the ground PE polymers.

[0020] T- Lavers

[0021] The multilayer fdms of this invention comprise one or more T-Layers. In some embodiments, the multilayer fdm comprises only one T-Layer. In some embodiments, the multilayer film comprises two T- Layers. In some embodiments, the multilayer film comprises three or more T-Layers.

[0022] Each T-Layer independently comprises (or consists essentially of) a first LLDPE polymer, called

[0023] T-LLDPE, that has a melt index of 0.2 dg / min to 4.0 dg / min and an MWCDI less than -1.0. In some embodiments, the T-LLDPE has a density of at least 0.905 g / cc, or at least 0.908 g / cc, or at least 0.910 g / cc, or at least 0.912 g / cc, or at least 0.914 g / cc, or at least 0.916 g / cc, or at least 0.918 g / cc, or at least 0.920 g / cc, or at least 0.922 g / cc, or at least 0.923 g / cc, or at least 0.924 g / cc. In some embodiments, the T-LLDPE has a density of at most 0.930 g / cc, or at most 0.928 g / cc, or at most 0.926 g / cc, or at most 0.925 g / cc, or at most 0.924 g / cc.

[0024] In some embodiments, the T-LLDPE has a melt index (12) of at least 0.3 dg / min, or at least 0.4 dg / min, or at least 0.5 dg / min. In some embodiments, the T-LLDPE has a melt index (12) of at most 4.0 dg / min or at most 3.5 dg / min or at most 3.0 dg / min or at most 2.5 dg / min or at most 2.2 dg / min or at most 2.0 dg / min or at most 1.8 dg / min or at most 1.6 dg / min or at most 1.4 dg / min or at most 1.2 dg / min or at most 1.0 dg / min or at most 0.9 dg / min or at most 0.8 dg / min or at most 0.7 dg / min or at most 0.6 dg / min or at most 0.5 dg / min.

[0025] In some embodiments, the T-LLDPE has a molecular weight comonomer distribution index (MWCDI) of at most -1.1 or at most -1.2 or at most -1.3 or at most -1.4 or at most -1.5 or at most -1.6 or at most -1.7. In some embodiments, the T-LLDPE has an MWCDI of at least -3.0, or at least -2.5 or at least -2.3 or at least -2. 1 or at least -2.0 or at least -1.9 or at least -1.8.

[0026] In some embodiments, the T-LLDPE has a number average molecular weight (Mn) of at least 25,000 g / mol or at least 27,000 g / mol or at least 29,000 g / mol or at least 30,000 g / mol. In some embodiments, the T-LLDPE has a number average molecular weight (Mn) of at most 35,000 g / mol or at most 33,000 g / mol or at most 32,000 g / mol or at most 31,000 g / mol.

[0027] In some embodiments, the T-LLDPE has a weight average molecular weight (Mw) of at least 120,000 g / mol or at least 130,000 g / mol or at least 140,000 g / mol or at least 145,000 g / mol. In some embodiments, the T-LLDPE has a weight average molecular weight (Mw) of at most 180,000 g / mol or at most 170,000 g / mol or at most 160,000 g / mol or at most 150,000 g / mol.

[0028] In some embodiments, the T-LLDPE has a molecular weight distribution (Mw / Mn) of at least 4.0, or at least 4.5, or at least 4.7 or at least 4.9. In some embodiments, the T-LLDPE has a molecular weight distribution of at most 6.0, or at most 5.5, or at most 5.3, or at most 5.1.

[0029] In some embodiments, a 2 mil test film that is made from the T-LLDPE according to the procedures in the Test Methods has an Elmendorf tear strength of at least 700 gf, or at least 750 gf, or at least 800 gf, or at least 850 gf, or at least 900 gf, or at least 925 gf, or at least 950 gf. In some embodiments, a 2 mil test filmi that is made from the T-LLDPE according to the procedures in the Test Methods has an Elmendorf tear strength of less than 1500 gf or 1200 gf.

[0030] In some embodiments, a 2 mil test film that is made from the T-LLDPE according to the procedures in the Test Methods has a dart impact strength of at least 200 g, or at least 250 g, or at least 300 g, or at least 350 g, or at least 400 g, or at least 450 g, or at least 500 g, or at least 525 g, or at least 550 g. In some embodiments, a test film that is made from the T-LLDPE according to the procedures in the Test Methods has a dart impact strength of at most 750 g, or at most 700 g, or at most 650 g, or at most 600 g.

[0031] The T-Layer(s) collectively make up at least 20 volume percent of the multilayer film. The term “volume percent” herein means the thickness of a layer, as a percentage of the thickness of the entire film and is measured in accordance with the test methods below. In some embodiments, the T-Layers collectively make up at least 22 volume percent of the multilayer film, or at least 24 volume percent, or at least 25 volume percent, or at least 26 volume percent or at least 27 volume percent or at least 28 volume percent or at least 29 volume percent or at least 30 volume percent. In some embodiments, the T-Layers collectively make up at most 40 volume percent of the multilayer film, or at most 38 volume percent, or at most 36 volume percent, or at most 35 volume percent, or at most 34 volume percent, or at most 33 volume percent, or most 32 volume percent, or most 31 volume percent, or at most 30 volume percent.

[0032] In some embodiments, two or more individual T-Layers of the multilayer film have the same thickness. Alternatively, in some embodiments, two or more individual T-Layers of the multilayer film have different thicknesses.

[0033] In some embodiments, each individual T-Layer independently make up at least 5 volume percent of the multilayer film, or at least 8 volume percent, or at least 10 volume percent, or at least 11 volume percent, or at least 12 volume percent, or at least 13 volume percent, or at least 14 volume percent, or at least 15 volume percent. In some embodiments, each individual T-Layer independently make up at most 40 volume percent of the multilayer film, or at most 35 volume percent, or at most 30 volume percent, or at most 25 volume percent, or at most 23 volume percent, or at most 21 volume percent, or at most 20 volume percent, or at most 19 volume percent, or at most 18 volume percent, or most 17 volume percent, or most 16 volume percent, or at most 15 volume percent.

[0034] At least one face layer of the multilayer film is a T-Layer. In some embodiments, both face layers of the multilayer film are T-Layers. In some embodiments, at least one internal layer of the multilayer film is a T-Layer, and in some embodiments, no internal layers of the multilayer film are T-Layers.

[0035] I-Layers

[0036] The multilayer film comprises one or more I-Layers. In some embodiments, the multilayer film comprises only one I-Layer. In some embodiments, the multilayer film comprises two I-Layers. In some embodiments, the multilayer film comprises three or more I-Layers.

[0037] Each I-Layer independently comprises (or consists essentially of) a second LLDPE polymer, called I-LLDPE, having a melt index of 0.4 dg / min to 4.0 dg / min and an MWCDI greater than 1.0.

[0038] In some embodiments, the I-LLDPE has a density of at least 0.905 g / cc, or at least 0.910 g / cc, or at least 0.912 g / cc, or at least 0.914 g / cc, or at least 0.915 g / cc, or at least 0.916 g / cc, or at least 0.917 g / cc, or at least 0.918 g / cc. In some embodiments, the I-LLDPE has a density of at most 0.930 g / cc, or at most 0.928 g / cc, or at most 0.926 g / cc, or at most 0.924 g / cc, or at most 0.922 g / cc, or at most 0.920 g / cc, or at most 0.919 g / cc, or at most 0.918 g / cc, or at most 0.917 g / cc.

[0039] In some embodiments, the I-LLDPE has a melt index (12) of at least 0.45 dg / min, or at least 0.50 dg / min, or at least 0.55 dg / min, or at least 0.60 dg / min, or at least 0.65 dg / min, or at or at least 0.70 dg / min, or at least 0.72 dg / min, or at least 0.74 dg / min, or at least 0.76 dg / min, or at least 0.78 dg / min, or at least 0.80 dg / min, or at least 0.82 dg / min, or at least 0.83 dg / min, or at least 0.84 dg / min, or at least 0.85 dg / min. In some embodiments, the I-LLDPE has a melt index (12) of at most 4 dg / min, or at most 3.5 dg / min, or at most 3.0 dg / min, or at most 2.5 dg / min, or at most 2.2 dg / min, or at most 2.0 dg / min, or at most 1.8 dg / min, or at most 1.6 dg / min, or at most 1.4 dg / min, or at most 1.2 dg / min, or at most 1.1 dg / min, or at most 1.0 dg / min, or at most 0.9 dg / min, or at most 0.85 dg / min.

[0040] In some embodiments, the I-LLDPE has a molecular weight comonomer distribution index (MWCDI) of at least 1.2, or at least 1.4, or at least 1.6, or at least 1.8, or at least 2.0, or at least 2.2, or at least 2.4, or at least 2.6, or at least 2.8, or at least 3.0, or at least 3.2, or at least 3.4, or at least 3.6. In some embodiments, the I-LLDPE has an MWCDI of at most 5.0, or at most 4.5, or at most 4.3, or at most 4.1, or at most 3.8, or at most 3.6, or at most 3.4, or at most 3.2, or at most 3.0.

[0041] In some embodiments, the I-LLDPE has a number average molecular weight (Mn) of at least 25,000 g / mol, or at least 27,000 g / mol, or at least 29,000 g / mol, or at least 30,000 g / mol. In some embodiments, the I-LLDPE has a number average molecular weight (Mn) of at most 35,000 g / mol, or at most 34,000 g / mol, or at most 33,000 g / mol, or at most 32,000 g / mol.

[0042] In some embodiments, the I-LLDPE has a weight average molecular weight (Mw) of at least 90,000 g / mol, or at least 95,000 g / mol, or at least 100,000 g / mol, or at least 110,000 g / mol. In some embodiments, the I-LLDPE has a weight average molecular weight (Mw) of at most 130,000 g / mol, or at most 120,000 g / mol, or at most 118,000 g / mol, or at most 115,000 g / mol.

[0043] In some embodiments, the I-LLDPE has a molecular weight distribution (Mw / Mn) of at least 2.0 or 2.3 or 2.5 or 2.7, or at least 2.9, or at least 3.1, or at least 3.3, or at least 3.5. In some embodiments, the I-LLDPE has a molecular weight distribution (Mw / Mn) of at most 4.5, or at most 4.3, or at most 4. 1, or at most 3.9, or at most 3.7.

[0044] In some embodiments, a 2 mil test fdm made from the I-LLDPE according to the Test Methods has a dart impact strength of at least 1500 g, or at least 1600 g or at least 1700 g or at least 1800 g or at least 1900 g or at least 2000 g or at least 2100 g. In some embodiments, a 2 mil test fdm made from the I- LLDPE according to the Test Methods has a dart impact strength of at most 3000 g or 2500 g.

[0045] In some embodiments, a 2 mil test fdm made from the I-LLDPE according to the Test Methods has an Elmendorf tear strength (MD) of at least 300 g, or at least 350 g or at least 400 g or at least 450 g or at least 480 g or at least 500 g. In some embodiments, a 2 mil test fdm made from the I-LLDPE according to the Test Methods has an Elmendorf tear strength (MD) of at most 800, or at most 700 or at most 650 or at most 600.

[0046] The I-Layers collectively make up at least 5 volume percent of the multilayer fdm. In some embodiments, the I-Layers collectively make up at least 6 volume percent of the multilayer fdm, or at least 7 volume percent, or at least 8 volume percent, or at least 9 volume percent, or at least 10 volume percent, or at least 11 volume percent, or at least 12 volume percent. In some embodiments, the I-Layers collectively make up at most 25 volume percent of the multilayer fdm, or at most 22 volume percent, or at most 20 volume percent, or at most 18 volume percent, or at most 16 volume percent, or at most 15 volume percent, or at most 14 volume percent, or at most 13 volume percent, or most 12 volume percent, or most 11 volume percent, or at most 10 volume percent.

[0047] In some embodiments, two or more individual I-Layers of the multilayer fdm have the same thickness. Alternatively, in some embodiments, two or more individual I-Layers of the multilayer fdm have different thicknesses.

[0048] In some embodiments, each individual I-Layer independently makes up at least 5 volume percent of the multilayer fdm, or at least 6 volume percent, or at least 7 volume percent, or at least 8 volume percent, or at least 9 volume percent, or at least 10 volume percent, or at least 11 volume percent, or at least 12 volume percent. In some embodiments, each individual I-Layer independently makes up at most 20 volume percent of the multilayer fdm, or at most 18 volume percent, or at most 16 volume percent, or at most 15 volume percent, or at most 14 volume percent, or at most 13 volume percent, or most 12 volume percent, or most 11 volume percent, or at most 10 volume percent.

[0049] In some embodiments, an I-Layer is a face layer of the multilayer fdm. In some embodiments, all I-Layers are internal layers. In some embodiments, I-Layers are neither a face layer nor directly in contact with a face layer.

[0050] B-Layers

[0051] The multilayer fdm may optionally comprise one or more B-Layers. In some embodiments, the multilayer fdm comprises only a single B-Layer. In some embodiments, the multilayer fdm comprises two B-Layers. In some embodiments, the multilayer fdm comprises three or more B-Layers.

[0052] Each B-Layer independently comprises (or consists essentially of) a third LLDPE polymer, called B-LLDPE, that has a melt index of 0.4 dg / min to 4.0 dg / min and an MWCDI from -1.0 to 1.0.

[0053] In some embodiments, the B-LLDPE has a density of at least 0.905 g / cc, or at least 0.910 g / cc, or at least 0.912 g / cc, or at least 0.914 g / cc, or at least 0.916 g / cc, or at least 0.918 g / cc, or at least 0.919 g / cc, or at least 0.920 g / cc. In some embodiments, the B-LLDPE has a density of at most 0.930 g / cc, or at most 0.928 g / cc, or at most 0.926 g / cc, or at most 0.925 g / cc, or at most 0.924 g / cc, or at most 0.923 g / cc, or at most 0.922 g / cc, or at most 0.921 g / cc, or at most 0.920 g / cc. In some embodiments, the B-LLDPE has a melt index (12) of at least 0.45 dg / min, or at least 0.50 dg / min, or at least 0.55 dg / min, or at least 0.60 dg / min, or at least 0.62 dg / min, or at least 0.64 dg / min, or at least 0.66 dg / min, or at least 0.68 dg / min, or at least 0.70 dg / min, or at least 0.72 dg / min, or at least 0.73 dg / min or at least 0.75 dg / min. In some embodiments, the B-LLDPE has a melt index (12) of at most 3.5 dg / min or at most 3.0 dg / min or at most 2.5 dg / min or at most 2.2 dg / min or at most 2.0 dg / min or at most 1.8 dg / min or at most 1.6 dg / min or at most 1.5 dg / min or at most 1.3 dg / min or at most 1.1 dg / min or at most 1.0 dg / min or at most 0.90 dg / min or at most 0.85 dg / min or at most 0.82 dg / min or at most 0.80 dg / min or at most 0.78 dg / min or at most 0.75 dg / min.

[0054] In some embodiments, the B-LLDPE has a molecular weight comonomer distribution index (MWCDI) of at least -0.9 or at least -0.8 or at least -0.75 or at least -0.6 or at least -0.4 or at least -0.2 or at least 0.0. In some embodiments the B-LLDPE has an MWCDI of at most 0.9 or at most 0.8 or at most 0.6 or at most 0.4 or at most 0.2 or at most 0.0 or at most -0.2 or at most -0.4 or at most -0.6.

[0055] In some embodiments, the B-LLDPE has a number average molecular weight (Mn) of at least 20,000 g / mol, or at least 24,000 g / mol, or at least 25,000 g / mol, or at least 26,000 g / mol. In some embodiments, the B-LLDPE has a number average molecular weight (Mn) of at most 33,000 g / mol, or at most 30,000 g / mol, or at most 29,000 g / mol, or at most 28,000 g / mol.

[0056] In some embodiments, the B-LLDPE has a weight average molecular weight (Mw) of at least 100,000 g / mol, or at least 110,000 g / mol, or at least 120,000 g / mol, or at least 125,000 g / mol. In some embodiments, the B-LLDPE has a weight average molecular weight (Mw) of at most 175,000 g / mol, or at most 150,000 g / mol, or at most 140,000 g / mol, or at most 135,000 g / mol.

[0057] In some embodiments, the B-LLDPE has a molecular weight distribution (Mw / Mn) of at least 4.0, or at least 4.5, or at least 4.6, or at least 4.7. In some embodiments, the B-LLDPE has a molecular weight distribution of at most 6.0, or at most 5.8, or at most 5.5, or at most 5.3, or at most 5. 1, or at most 4.9.

[0058] In some embodiments, a 1 mil test film made from the B-LLDPE according to the Test Methods has an Elmendorf tear strength of at least 300 g, or at least 320 g or at least 340 g or at least 360 g or at least 380 g or at least 400 g. In some embodiments, a 1 mil test film made from the B-LLDPE according to the Test Methods has an Elmendorf tear strength of at most 600 g or 500 g.

[0059] In some embodiments, a 1 mil test film made from the B-LLDPE according to the Test Methods has a dart impact strength of at least 400 g, or at least 450 g, or at least 500 g, or at least 520 g, or at least 540 g, or at least 560 g, or at least 580 g, or at least 600 g, or at least 620 g. In some embodiments, a 1 mil test film made from the B-LLDPE according to the Test Methods has a dart impact strength of at most 1000 g or 800 g. In some embodiments, a 1 mil test film made from the B-LLDPE according to the Test Methods has a dart impact strength that is at least 50 percent of Elmendorf tear strength (g / gf), or at least 60 percent or at least 70 percent or at least 80 percent or at least 90 percent or at least 100 percent. In some embodiments, a 1 mil test film made from the B-LLDPE according to the Test Methods has a dart impact strength that is at most 250 percent of Elmendorf tear strength (g / gf), or at most 200 percent or at most 180 percent or at most 160 percent or at most 150 percent.

[0060] In some embodiments, the B-Layers collectively make up 0 volume percent of the multilayer fdm or at least 5 volume percent or at least 10 volume percent or at least 15 volume percent or at least 17 volume percent or at least 19 volume percent or at least 20 volume percent or at least 22 volume percent or at least 24 volume percent or at least 26 volume percent or at least 28 volume percent or at least 30volume percent. In some embodiments, the B-Layers collectively make up at most 40 volume percent of the multilayer fdm or at most 38 volume percent or at most 36 volume percent or at most 35 volume percent or at most 34 volume percent or at most 32 volume percent or at most 30 volume percent.

[0061] In some embodiments, two or more individual B-Layers within the multilayer fdm have the same thickness. Alternatively, in some embodiments, two or more individual B-Layers within the multilayer fdm have different thicknesses.

[0062] In some embodiments, each individual B-Layer independently makes up at least 5 volume percent of the multilayer fdm, or at least 8 volume percent or at least 10 volume percent or at least 11 volume percent of the multilayer fdm or at least 12 volume percent or at least 13 volume percent or at least 14 volume percent or at least 15 volume percent. In some embodiments, each individual B-Layer independently makes up at most 35 volume percent of the multilayer fdm or at most 30 volume percent or at most 25 volume percent or at most 20 volume percent or at most 19 volume percent or at most 18 volume percent or at most 17 volume percent or at most 16 volume percent or at most 15 volume percent.

[0063] In some embodiments, a B-Layer is a face layer of the multilayer fdm. In some embodiments, all B-Layers are internal layers. In some embodiments, one or more B-Layers are internal layers directly in contact with the face layers.

[0064] R-Layers

[0065] The multilayer fdms of this invention comprise one or more R-Layers. The R-Layer comprise a recycled LLDPE composition. In some embodiments, the multilayer fdm comprises only a single R-Layer. In some embodiments, the multilayer fdm comprises two R-Layers. In some embodiments, the multilayer fdm comprises three or more R-Layers.

[0066] Each R-Layer independently comprises (or consists essentially of) a recycled LLDPE composition, called R-LLDPE, that comprises recycled LLDPE polymers. The quantity of recycled LLDPE polymers in the R-Layers is selected such that the multilayer fdm comprises at least 10 weight percent recycled LLDPE polymers. The term “recycled LLDPE polymers” as used herein refers to LLDPE polymers that have been exposed to at least one melting process. Lor instance, as known by those skilled in the art, LLDPE polymers may be heated and extruded for forming finished articles, where the heating or extrusion involves a melting process to form finished articles. In many instances, recycled LLDPE compositions are sold as blends with virgin LLDPE polymer, so that the recycled polymer content of a R-Layer is only a fraction of the R-Layer. In order to meet goals for recycled content, the thickness of R-Layers may be increased to account for virgin content in the R- Layer. In some embodiments, the R-LLDPE comprises at least 50 weight percent LLDPE recycled polymers, or at least 55 weight percent or at least 60 weight percent or at least 65 weight percent or at least 70 weight percent. In some embodiments, the R-LLDPE comprises at most 100 weight percent recycled LLDPE polymers or at most 95 weight percent or at most 90 weight percent or at most 85 weight percent or at most 80 weight percent or at most 75 weight percent or at most 70 weight percent.

[0067] In some embodiments, the R-LLDPE comprises pre-consumer recycled LLDPE polymers. In some embodiments, the R-LLDPE comprises post-consumer recycled (PCR) LLDPE polymers. In some embodiments, more than 50 weight percent of the recycled LLDPE in the R-LLDPE is PCR LLDPE polymers, or more than 60 weight percent or more than 70 weight percent.

[0068] In some embodiments, the R-LLDPE has a density of at least 0.905 g / cc or at least 0.910 g / cc or at least 0.912 g / cc or at least 0.914 g / cc or at least 0.915 g / cc or at least 0.916 g / cc or at least 0.917 g / cc or at least 0.918 g / cc. In some embodiments, the R-LLDPE has a density of at most 0.930 g / cc or at most 0.928 g / cc or at most 0.926 g / cc or at most 0.924 g / cc or at most 0.922 g / cc or at most 0.921 g / cc or at most 0.920 g / cc or at most 0.919 g / cc or at most 0.918 g / cc.

[0069] In some embodiments, the R-LLDPE has a melt index (12) of at least 0.5 dg / min or at least 0.6 dg / min or at least 0.8 dg / min or at least 1.0 dg / min or at least 1.2 dg / min or at least 1.4 dg / min or at least 1.5 dg / min or at least 1.6 dg / min or at least 1.7 dg / min. In some embodiments, the R-LLDPE has a melt index (12) of at most 3.5 dg / min or at most 3.0 dg / min or at most 2.5 dg / min or at most 2.2 dg / min or at most 2.0 dg / min or at most 1.8 dg / min or at most 1.7 dg / min.

[0070] In some embodiments, the R-Layers collectively make up at least 12 volume percent recycled polymer or at least 14 volume percent or at least 16 volume percent or at least 18 volume percent or at least 20 volume percent or at least 22 volume percent or at least 24 volume percent or at least 25 volume percent or at least 26 volume percent or at least 28 volume percent or at least 30 volume percent. In some embodiments, the R-Layers collectively make up at most 50 volume percent of the multilayer fdm or at most 45 volume percent or at most 42 volume percent or at most 40 volume percent or at most 38 volume percent or at most 36 volume percent or at most 35 volume percent or at most 34 volume percent or at most 32 volume percent or at most 30 volume percent.

[0071] In some embodiments, the R-Layers are selected such that the multilayer fdm comprises at least 12 weight percent recycled polymer or at least 14 weight percent or at least 16 weight percent or at least 18 weight percent or at least 20 weight percent or at least 22 weight percent or at least 24 weight percent or at least 25 weight percent or at least 26 weight percent or at least 28 weight percent or at least 30 weight percent. In some embodiments, the R-Layers are selected such that the multilayer fdm comprises at most 50 weight percent recycled polymer or at most 42 weight percent or at most 40 weight percent or at most 38 weight percent or at most 36 weight percent or at most 34 weight percent or at most 32 weight percent or at most 30 weight percent.

[0072] In some embodiments, two or more individual R-Layers within the multilayer fdm have the same thickness. Alternatively, in some embodiments, two or more individual R-Layers within the multilayer fdm have different thicknesses.

[0073] In some embodiments, each individual R-Layer in the multilayer fdm independently makes up at least 5 volume percent of the multilayer fdm or at least 8 volume percent or at least 10 volume percent or at least 11 volume percent or at least 12 volume percent or at least 13 volume percent or at least 14 volume percent or at least 15 volume percent. In some embodiments, each individual R-Layer in the multilayer fdm independently makes up at most 40 volume percent of the multilayer fdm or at most 35 volume or at most 30 volume or at most 25 volume or at most 23 volume or at most 21 volume or at most 20 volume or at most 19 volume percent or at most 18 volume percent or at most 17 volume percent or at most 16 volume percent or at most 15 volume percent.

[0074] In some embodiments, an R-Layer is a face layer of the multilayer fdm. In some embodiments, all R-Layers are internal layers.

[0075] Additives:

[0076] Polymers or layers of the multilayer fdm may optionally comprise additives. Examples of common additives include compatibilizers, antistatic agents, color enhancers, dyes, lubricants, fdlers, pigments, primary antioxidants, secondary antioxidants, processing aids, UV stabilizers, nucleators, slip agents such as erucamide, antiblock agents such as talc, and combinations thereof. In some embodiments, additives make up no more than 5 weight percent of the polymers in the layer or no more than 4 weight percent or no more than 3 weight percent or no more than 2 weight percent or no more than 1 weight percent. In some embodiments, additives make up essentially 0 weight percent of the polymers in the layer.

[0077] Co-Extrusion and Multilayer Film:

[0078] The polymer compositions described for each layer may be coextruded by known processes to form the multilayer fdm. The polymers can be melted in separate extruders. The molten polymers are fed to an extrusion die. The die is designed to extrude each polymer as one or more discrete and continuous layers in a multilayer fdm. Suitable equipment is commercially available, such as under the Hosokawa Alpine trademark.

[0079] In a cast fdm extrusion, the die is a slot die, and the multilayer fdm is extruded onto a chill roll, quenched, and wound onto a roll.

[0080] In a blown fdm extrusion, the die is an annular die which forms a tube of multilayer polymer fdm. A gas bubble (such as air or nitrogen) is trapped inside the tubular fdm between the die and a pair of downstream nip rollers. The multilayer film passes over the air bubble before it solidifies and is biaxially stretched. The multilayer film is cooled, slit, flattened and wound into a roll.

[0081] The result of the coextrusion is a multilayer film.

[0082] Multilayer films of this invention comprise at least three layers: A first face layer that is a T-Layer; An R-layer; and An I-layer.

[0083] In some embodiments, the multilayer film comprises four layers. In some embodiments, the 4- layer film comprises: A first face layer that is a T-Layer; An internal R-Layers; An internal I-Layer; and A second face layer that is a T-Layer.

[0084] In some embodiments, the 4-layer film comprises: A first face layer that is a T-Layer; An R-Layer; An I- Layer; and A B-Layer.

[0085] Any of the R-Layer, I-Layer and B-Layer may be a face layer, and the internal layers may be in the order listed or a different order.

[0086] In some embodiments, multilayer films of this invention comprise at least five layers. In some embodiments, the 5-layer film comprises: A first face layer that is a T-Layer; An internal R-layer; An internal I-layer; An internal B-layer; and A second face layer that is a T-Layer.

[0087] In the 5-layer film above and the multilayer films below, internal layers may be in the order listed or in any other order. In some embodiments, identical layers will not be adjacent to each other. In some embodiments, the 5-layer film comprises: A first face layer that is a T-Layer; A first internal R-layer; An internal I-layer; A second internal R-layer; and A second face layer that is a T-Layer.

[0088] In some embodiments, the multilayer film comprises six layers. In some embodiments, the 6-layer film comprises: A first face layer that is a T-Layer; Two internal R-Layers; An internal I-Layer; An internal B-Layer; and A second face layer that is a T-Layer. In some embodiments, the 6-layer film comprises: A first face layer that is a T-Layer; An internal R-Layer; An internal I-Layer; Two internal B-Layers; and A second face layer that is a T-Layer. In some embodiments, the 6-layer film comprises: A first face layer that is a T-Layer; An internal R-Layer; Two internal I-Layers; An internal B-Layer; and A second face layer that is a T-Layer. In some embodiments, the multilayer film comprises seven layers. In some embodiments, the 7-layer film comprises: A first face layer that is a T-Layer; Two internal R-Layers; An internal I-Layer; Two internal B-Layers; and A second face layer that is a T-Layer.

[0089] In some embodiments, the 7-layer film comprises - A first face layer that is a T-Layer; Two internal R- Layers; Two internal I-Layers; An internal B-Layer; and A second face layer that is a T-Layer.

[0090] In some embodiments, the 7-layer film comprises: A first face layer that is a T-Layer; An internal R- Layer; Two internal I-Layers; Two internal B-Layers; and A second face layer that is a T-Layer.

[0091] In some embodiments, the multilayer film comprises eight layers or more layers. Multilayer films with eight or more layers may comprise the layers recited above for 5-, 6- or 7-layer films, plus one or more additional layers. In some embodiments, all layers of the multilayer film comprise or consist essentially of LLDPE polymers and recycled LLDPE compositions.

[0092] In some embodiments, multilayer films that comprise four or more layers may optionally comprise one or more layers of polymer other than LLDPE. Common polyolefin layers that may be included in the multilayer films include high density polyethylene (HDPE), low density polyethylene (LDPE) or very low density linear low density polyethylene (VLDPE, also called ultra-low density linear low density polyethylene or ULDPE). Common non-polyolefm polymers that may be included in the multilayer films include polyethylene terephthalate (PET) such as Mylar, polystyrene (PS and high impact polystyrene, HIPS), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyamides (PA) including nylons, ethylene vinyl alcohol (EVOH), ethylene-vinyl acetate (EVA). Barrier layers often comprise EVOH, polyamide or PVDC. Heat seal layers sometimes comprise polyethylene elastomer or EVA.

[0093] In some embodiments, multilayer films that comprise four or more layers may comprise one or more tie layers. Tie layers improve the adhesion between different layers of polymer that have poor adhesion to each other. The tie layer usually comprises a polymer or polymer blend that has good adhesion to both of the layers that are adjacent to the tie layer. Examples of common tie layers are commercially available under the trademarks BYNEL™, Plexar, EMAC, Surpass and Novapol.

[0094] In some embodiments, the I-Layer(s) are not directly in contact with the face layers. For example:

[0095] • In a 5 -layer film, the I-Layer is in layer 3, counting from one face layer to the other face layer; or

[0096] • In a 6-layer film, an I-Layer is in layer 3 or 4, counting from one face layer to the other face layer; or

[0097] • In a 7-layer film, an I-Layer is in layer 3, 4 or 5, counting from one face layer to the other face layer; or

[0098] • In a 7-layer film, an I-Layer is in layer 4, counting from one face layer to the other face layer.

[0099] In some embodiments, a 7-layer film comprises, in order: A first face layer that is a T-Layer; A first internal B-Layer; A first internal R-Layer; An internal I-Layer; A second internal R-Layer; A second internal B-Layer; and A second face layer that is a T-Layer.

[0100] In some embodiments, the multilayer film is at least 0.5 mil (13 microns) thick, or at least 0.6 mils (15 microns) or at least 0.7 mils (18 microns) or at least 0.8 mils (20 microns) or at least 0.9 mils (23 microns) or at least 1 mils (25 microns) or at least 1.2 mils (30 microns) or at least 1.5 mils (38 microns) or at least 2 mils (50 microns) or at least 2.5 mils (60 microns) or at least 3 mils (75 microns). In some embodiments, the multilayer film is at most 8 mils (200 microns) or at most 7 mils (180 microns) or at most 6 mils (150 microns) or at most 5 mils (130 microns) or at most 4 mils (100 microns)or at most 3.5 mils (90 microns) or at most 3 mils (75 microns) or at most 2.5 mils (60 microns) or at most 2 mils (50 microns) or at most 1.5 mils (15 microns) or at most 1.2 mils (30 microns) or at most 1 mil (25 microns) or at most 0.9 mils (23 microns). In some embodiments, a 0.9 mil (23 micron) multilayer film of this invention (or from 0.8 mil to 1.0 mil) has a dart impact strength of at least 250 g or at least 275 g or at least 290 g or at least 300 g or at least 320 g or at least 340 g or at least 360 g or at least 380 g or at least 400 g. There is no maximum desired dart impact strength, but in some embodiments the dart impact strength for a 0.9 mil film does not need to exceed 800 g or 500 g.

[0101] In some embodiments, a 0.9 mil (23 micron) multilayer film of this invention has an Elmendorf tear strength in the machine direction of at least 250 gf or at least 275 gf or at least 290 gf or at least 300 gf or at least 320 gf or at least 340 gf or at least 360 gf or at least 370 gf. There is no maximum desired Elmendorf tear strength, but in some embodiments the dart impact strength for a 0.9 mil film does not need to exceed 700 gf or 500 gf.

[0102] In some embodiments, a multilayer film of this invention has a dart impact strength of at least 275 g / mil or at least 300 g / mil or at least 325 g / mil or at least 350 g / mil or at least 375 g / mil or at least 400 g / mil or at least 450 g / mil. There is no maximum desired dart impact strength, but in some embodiments the dart impact strength for a film of this invention does not need to exceed 800 g / mil or 600 g / mil.

[0103] In some embodiments, a multilayer film of this invention has an Elmendorf tear strength in the machine direction of at least 250 gf / mil or at least 275 gf / mil or at least 300 gf / mil or at least 325 gf / mil or at least 350 gf / mil or at least 375 gf / mil or at least 400 gf / mil. There is no maximum desired Elmendorf tear strength, but in some embodiments the Elmendorf tear strength for a film does not need to exceed 800 gf / mil or 600 gf / mil.

[0104] The multilayer film can be used for ordinary purposes, such as wraps, packaging and bags. In some embodiments, the multilayer film is formed into a trash bag. In some embodiments, a bag is made by heat sealing three sides of two flat films layered onto each other. In some embodiments, a bag is made by heat sealing a tubular film - transverse to the direction of the tube, and then cutting or perforating the tube parallel to the heat seal at a distance suitable for the desired size of the bag. In some embodiments, the multilayer film may be strengthened by supporting it with a woven mesh or cloth.

[0105] The makeup of the resulting bag reflects the makeup of the multilayer film, as previously described.

[0106] The invention includes, but is not limited to, the following aspects:

[0107] Aspect 1. A multilayer film comprising two face layers and at least one internal layer, wherein the film comprises:

[0108] (a) at least 20 volume percent of one or more layers, called “T-Layers”, that comprise a first LLDPE polymer, called “T-LLDPE”, having a melt index (12) of 0.2 dg / min to 4.0 dg / min and an MWCDI less than -1.0, and wherein at least one face Layer is a T-Layer; (b) at least 5 volume percent of one or more layers, called “I-Layers”, that comprise a second LLDPE polymer, called “I-LLDPE”, having a melt index (12) of 0.4 dg / min to 4.0 dg / min and an MWCDI greater than 1.0;

[0109] (c) at least 10 volume percent of one or more layers, called “R-Layers”, that comprise a recycled LLDPE composition, called “R-LLDPE”, that comprises recycled LLDPE polymers;

[0110] (d) optionally, one or more layers, called “B-Layers”, that comprise a third LLDPE composition, called “B-LLDPE”, having a melt index (12) of 0.4 dg / min to 4.0 dg / min and an MWCDI from -1.0 to 1 .0; and and wherein the fdm comprises at least 10 weight percent recycled LLDPE polymers, based on the total weigh of the fdm.

[0111] Aspect 2. The multilayer-fdm of Aspect 1 which comprises at least four layers and wherein both face layers are T-Layers.

[0112] Aspect 3. The multilayer-fdm of Aspect 1 which comprises at least four layers and wherein at least one layer is a B-Layer.

[0113] Aspect 4. The multilayer-fdm of Aspect 1 which comprises at least five layers, wherein both face layers are T-Layers and at least one internal layer is a B-Layer.

[0114] Aspect 5. The multilayer fdm of Aspect 4 wherein the T-LLDPE has (a) a density of 0.920 g / cc to 0.928 g / cc, (b) a melt index of 0.4 dg / min to 0.7 dg / min, and (c) an MWCDI from -1.5 to -2.5.

[0115] Aspect 6. The multilayer fdm of Aspect 5 wherein the T-LLDPE has a weight average molecular weight from 140,000 g / mol to 160,000 g / mol and a molecular weight distribution from 4.5 to 5.5.

[0116] Aspect 7. The multilayer fdm of Aspect 4 wherein the I-LLDPE has (a) a density of 0.910 g / cc to 0.920 g / cc, (b) a melt index of 0.70 dg / min to 1. 1 dg / min, and (c) an MWCDI from 2 to 4.

[0117] Aspect 8. The multilayer fdm of Aspect 7 wherein the I-LLDPE has a weight average molecular weight from 100,000 g / mol to 130,000 g / mol and a molecular weight distribution (Mw / Mn) from 2.5 to 4.5.

[0118] Aspect 9. The multilayer fdm of Aspect 4 wherein the B-LLDPE has (a) a density of 0.916 g / cc to 0.924 g / cc, (b) a melt index of 0.55 dg / min to 0.90 dg / min, and (c) an MWCDI from 0.0 to -1.0.

[0119] Aspect 10. The multilayer fdm of Aspect 9 wherein the B-LLDPE has a weight average molecular weight from 120,000 g / mol to 150,000 g / mol and a molecular weight distribution from 4 to 6.

[0120] Aspect 11. The multilayer fdm of Aspect 4 wherein:

[0121] (a) The T-LLDPE has (i) a density of 0.920 g / cc to 0.928 g / cc, (ii) a melt index (12) of 0.4 dg / min to 0.7 dg / min, and (iii) an MWCDI from -1.5 to -2.5; and

[0122] (b) The I-LLDPE has (i) a density of 0.910 g / cc to 0.920 g / cc, (ii) a melt index (12) of 0.70 dg / min to 1.1 dg / min, and (iii) an MWCDI from 2 to 4; and (c) the B-LLDPE has (i) a density of 0.916 g / cc to 0.924 g / cc, (ii) a melt index (12) of 0.55 dg / min to 0.90 dg / min, and (iii) an MWCDI from 0.0 to -1.0.

[0123] Aspect 12. The multilayer fdm of Aspect 11 wherein

[0124] (a) the T-Layer(s) collectively make up from 25 to 35 volume percent of the multilayer fdm;

[0125] (b) the I-Layer(s) collectively make up from 8 to 15 volume percent of the multilayer fdm;

[0126] (c) the B-Layer(s) collectively make up from 25 to 35 volume percent of the multilayer fdm; and

[0127] (d) the R-Layer(s) collectively make up from 25 to 35 volume percent of the multilayer fdm.

[0128] Aspect 13. The multilayer film of Aspect 11 which is a 7-layer fdm comprising, in order, the following layers:

[0129] (a) From 10 to 20 volume percent of a first face layer, which is a T-Layer;

[0130] (b) From 10 to 20 volume percent of a first internal B-Layer;

[0131] (c) From 10 to 20 volume percent of a first internal R-Layer;

[0132] (d) From 5 to 15 volume percent of an internal I-Layer;

[0133] (e) From 10 to 20 volume percent of a second internal R-Layer;

[0134] (f) From 10 to 20 volume percent of a second internal B-Layer; and

[0135] (g) From 10 to 20 volume percent of a second face layer, which is a T-Layer.

[0136] Aspect 14. The multilayer film of Aspect 5 wherein a 2 mil test film that is made from the T-LLDPE has an Elmendorf tear strength of at least 800 gf.

[0137] Aspect 15. The multilayer film of Aspect 7 wherein a 2 mil test fdm that is made from the I-LLDPE has a dart impact strength of at least 1800 g.

[0138] Aspect 16. The multilayer fdm of Aspect 9 wherein a 1 mil test fdm that is made from the B-LLDPE has an Elmendorf tear strength of at least 320 g and a dart impact strength of at least 450 g.

[0139] Aspect 17. The multilayer fdm of Aspect 12 wherein:

[0140] (a) a 2 mil test fdm that is made from the T-LLDPE has an Elmendorf tear strength of at least 800 gf; and

[0141] (b) a 2 mil test fdm that is made from the I-LLDPE has a dart impact strength of at least 1800 g; and

[0142] (c) a 1 mil test fdm that is made from the B-LLDPE has an Elmendorf tear strength of at least 320 g and a dart impact strength of at least 450 g.

[0143] Aspect 18. A bag comprising the multilayer film described in any one of Aspects 1 through 17, which comprises at least 20 weight percent recycled LLDPE polymers.

[0144] Aspect 19. The bag of Aspect 19 wherein the multi-layer fdm has (a) an average thickness of 0.8 to 1.0 mil; (b) an Elmendorf tear resistance (machine direction) of at least 250 gf; and (b) a dart impact resistance of at least 300 g. Test Methods

[0145] Parameters described in this application can be measured using the following measurements:

[0146] Volume Percent (Laver Thickness)

[0147] The thickness of each layer of multilayer film samples is determined via microscopy. A cross-section of the film is collected using a cryo-ultramicrotome, Leica EM UC7-FC7, equipped with a diamond knife at a thickness between 10-15 micrometer in depth. The section is then transferred to a glass slide containing silicone imaging oil. A glass coverslip is placed on top of the sample specimen. Digital micrographs of the cross section are acquired under microscopy (“Zeiss Z2M”). Individual layer thickness is measured using microscope software “ZEN 2 CORE” against a calibrated scale bar.

[0148] Molecular Weight Profile and Molecular Weight Distribution Index (MWCDI) Measurement by GPC Chromatography

[0149] The procedure uses a chromatographic system consisted of a PolymerChar GPC-IR (Valencia, Spain) high temperature GPC chromatograph equipped with an internal IR5 infra-red detector (IR5). The autosampler oven compartment is set at 160°C and the column compartment is set at 150°C. The columns are 4 Agilent “Mixed A” 30cm 20-micron linear mixed-bed columns. The chromatographic solvent is 1,2,4 trichlorobenzene and contains 200 ppm of butylated hydroxytoluene (BHT). The solvent source is nitrogen sparged. The injection volume is 200 microliters, and the flow rate is 1.0 milliliters / minute .

[0150] The GPC column set is calibrated with 21 narrow molecular weight distribution polystyrene standards with molecular weights ranging from 580 to 8,400,000 g / mol, supplied by Agilent Technologies. The standards are arranged in 6 “cocktail” mixtures with at least a decade of separation between individual molecular weights. The polystyrene standards are prepared at 0.025 grams in 50 milliliters of solvent for molecular weights equal to or greater than 1,000,000, and 0.05 grams in 50 milliliters of solvent for molecular weights less than 1,000,000. The polystyrene standards are predissolved at 80 °C with gentle agitation for 30 minutes then cooled and the room temperature solution is transferred cooled into the autosampler dissolution oven at 160°C for 30 minutes. The polystyrene standard peak molecular weights are converted to polyethylene molecular weights using Equation 1 (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)).: where M is the molecular weight, A has a value of 0.4113 and B is equal to 1.0.

[0151] A fifth order polynomial is used to fit the respective polyethylene-equivalent calibration points. The total plate count of the GPC column set is performed with decane, which is introduced into blank sample via a micropump controlled with the PolymerChar GPC-IR system. The plate count for the chromatographic system should be greater than 18,000 for the 4 Agilent “Mixed A” 30cm 20-micron linear mixed-bed columns.

[0152] Samples are prepared in a semi-automatic manner with the PolymerChar “Instrument Control” Software. The samples are weight-targeted at 2 mg / ml, and the solvent (contained 200ppm BHT) is added to a pre nitrogen-sparged septa-capped vial, via the PolymerChar high temperature autosampler. The samples are dissolved for 2 hours at 160° Celsius under “low speed” shaking.

[0153] The calculations of MU(GPC), MW(GPC), and MZ(GPC) are based on GPC results using the internal IR5 detector (measurement channel) of the PolymerChar GPC-IR chromatograph according to Equations 2-4, using PolymerChar GPCOne™ software, the baseline-subtracted IR chromatogram at each equally- spaced data collection point (i), and the polyethylene equivalent molecular weight obtained from the narrow standard calibration curve for the point (i) from Equation 1.

[0154] (EQ 4)

[0155] In order to monitor the deviations over time, a flowrate marker (decane) is introduced into each sample via a micropump controlled with the PolymerChar GPC-IR system. This flowrate marker (FM) is used to linearly correct the pump flowrate (Flowrate(nommai)) for each sample by RV alignment of the respective decane peak within the sample (RV(FM sample)) to that of the decane peak within the narrow standards calibration (RV(FM calibrated)). Any changes in the time of the decane marker peak are then assumed to be related to a linear-shift in flowrate (Flowrate(effective)) for the entire run. After calibrating the system based on a flow marker peak, the effective flowrate (with respect to the narrow standards calibration) is calculated as Equation 5. Processing of the flow marker peak is done via the PolymerChar GPCOne™ Software. Acceptable flowrate correction is such that the effective flowrate should be within + / -0.5 % of the nominal flowrate.

[0156] FloWratC(effective) Flowrate (nominal) * (RV(FM Calibrated) / RV(FM Sample)) (EQ5)

[0157] A calibration for the IR5 detector rationing is performed using at least ten ethylene-based polymer standards (Octene as comonomer) made by single-site metallocene catalyst from a single reactor in solution process (polyethylene homopolymer and ethylene / octene copolymers) with a narrow SCB distribution and known comonomer content (as measured by13C NMR Method, Qiu et al., Anal. Chem.2009, 81, 8585-8589), ranging from homopolymer (0 SCB / 1000 total C) to approximately 40 SCB / 1000 total C, where total C = carbons in backbone + carbons in branches. Each standard had a weight-average molecular weight from 36,000 g / mole to 126,000 g / mole measured by GPC. Each standard had a molecular weight distribution (Mw / Mn) from 2.0 to 2.5. Exemplary polymer properties for the SCB standards are shown in Table A.

[0158] Table A: “Copolymer” Standards

[0159] The “IR5 Area Ratio (or “IR5 Methyl Channel Area / IR5 Measurement Channel Area ”)” of “the baseline- subtracted area response of the IR5 methyl channel sensor” to “the baseline-subtracted area response of IR5 measurement channel sensor” (standard fdters and fdter wheel as supplied by PolymerChar: Part Number IR5 FWM01 included as part of the GPC-IR instrument) is calculated for each of the “Copolymer” standards. A linear fit of the SCB frequency versus the “IR5 Area Ratio” is constructed in the form of the following Equation 6:

[0160] SCB / 1000 total C = Ao + [Ai x (IR5 Methyl Channel Area / IR5 Measurement Channel Area)] (EQ 6) where Ao is the “SCB / 1000 total C” intercept at an “IR5 Area Ratio” of zero, and Ai is the slope of the “SCB / 1000 total C” versus “IR5 Area Ratio” and represents the increase in the SCB / 1000 total C as a function of “IR5 Area Ratio.” The IR5 area ratio is equal to the IR5 height ratio for narrow PDI and narrow SCBD standard materials.

[0161] The “IR5 Height Ratio” of “the baseline-corrected chromatogram (methyl channel)” to “the baseline-corrected chromatogram (measurement channel)” is calculated at each column elution volume index (each equally-spaced index, representing 1 data point per second at 1 ml / min elution) across the sample integration bounds. The “IR5 Height Ratio” is multiplied by the coefficient Ai, and the coefficient Ao is added to this result, to produce the predicted SCB frequency (SCBf) of the sample. The result is converted into mole percent comonomer (mol% comonomer) as follows in Equation 7:

[0162] Mol% Comonomer = {SCBf / [SCBf + ((1000 - SCBf * Comonomer Length) / 2)] }* 100 (Eqn. 7) where “SCBf” is the “SCB per 1000 total C”, and the “Comonomer Length” = 8 for octene, 6 for hexene, and so forth.

[0163] Each elution volume index is converted to a molecular weight value (Mw) using the method of Williams and Ward (described above; Eqn. 1). The “Mol% Comonomer (y axis) ” is plotted as a function of Log(Mwi), and the slope is calculated between Mwi of 15,000 and Mwi of 150,000 g / mole (end group corrections on chain ends were omitted for this calculation). (An EXCEL linear regression was used to calculate the slope between, and including, Mwi from 15,000 to 150,000 g / mole using a minimum of 100 equally-spaced data points of Log(Mwi) and Mol% Comonomer for the fit) This slope is defined as the molecular weighted comonomer distribution index (MWCDI = Molecular Weighted Comonomer Distribution Index).

[0164] EXAMPLES

[0165] Polymers used in the examples are made as follows:

[0166] T- LLDPE

[0167] T- LLDPE is made in a gas phase polymerization process using a catalyst system that includes UCAT™ J Ziegler-Natta catalyst and triethylaluminum (TEAL) cocatalyst.

[0168] The UCAT™ J Ziegler-Natta catalyst is partially activated by the following procedure. A 959 gram portion of the UCAT™ J catalyst slurry is added to a mixing vessel at room temperature. While stirring, 205 grams of 40 percent solution of tri-n-hexyl aluminum (TNHA) in mineral oil is added and stirred for 1 hour. Then 582 grams of a 12 percent solution of diethyl aluminum chloride (DEAC) in mineral oil is added and stirred for at least an additional hour prior to use.

[0169] The activated catalyst slurry is used to polymerize ethylene (C2) and 1 -hexene (C6) in a fluidized bed reactor. Polymerization is initiated by continuously feeding the partially activated catalyst and cocatalyst (trialkyl aluminum, specifically tri ethyl aluminum or TEAL fed as a 2.5% solution in isopentane) into a fluidized bed of polyethylene granules, together with ethylene, hydrogen, and 1- hexene. Nitrogen and isopentane make up the remaining pressure in the reactor. The polymerization is continuously conducted, after equilibrium is reached under the conditions as shown below in Table 2. The resulting granular product is continuously removed. Slip additive (erucamide) and anti-block additive (talc) are added to the polymer melt as shown in Table 4. The granular product is extruded and formed into pellets.

[0170] The properties of the T-LLDPE are shown in Table 4.

[0171] Table 1

[0172] B-LLDPE

[0173] B-LLDPE is made by solution polymerization in a loop reactor using a catalyst system that includes Ziegler-Natta catalyst and triethylaluminum (TEAL) cocatalyst. The heterogeneous Ziegler- Natta type catalyst-premix is prepared substantially according to U.S. Pat. No. 4,612,300, by sequentially adding to a volume of ISOPAR E, a slurry of anhydrous magnesium chloride in ISOPAR E, a solution of EtAlCh in heptane, and a solution of Ti(O-iPr)4 in heptane, to yield a composition containing a magnesium concentration of 0.20M and a ratio of Mg / Al / Ti of 40 / 12.5 / 3.

[0174] Ethylene and 1 -hexene monomer and the Isopar E solvent are purified with molecular sieves. High purity hydrogen is purified to remove residual moisture using a molecular sieve. Monomer, solvent and hydrogen feeds are pressurized to above reaction pressure before being introduced into the reactor. All catalyst components are individually flow controlled.

[0175] The total fresh feed stream to the reactor (solvent, monomer, comonomer and hydrogen) is temperature controlled to maintain a single solution phase by passing the feed stream through a heat exchanger. The total feed to the polymerization reactor is injected into the reactor at two locations with approximately equal reactor volumes between each location and with each injection zone receiving approximately half of the total reactor ethylene feed. The catalyst components are injected into the polymerization reactor independently. The primary catalyst component feed is computer controlled to maintain the reactor monomer conversion at the specified target. The cocatalyst component is fed based on calculated specified molar ratios to the primary catalyst component. Immediately following each reactor feed injection location, the feed streams are mixed with the circulating polymerization reactor contents with static mixing elements. The contents of the reactor are continuously circulated through heat exchangers responsible for removing much of the heat of reaction and with the temperature of the coolant side responsible for maintaining an isothermal reaction environment at the specified temperature. Circulation around the reactor loop is provided by a pump. Leeds and reaction conditions are shown in Table 2.

[0176] Table 2

[0177] The reactor effluent enters a zone where it is deactivated by the addition of water. At this same reactor exit location calcium stearate and tetrakis(methylene(3,5-di-tert-butyl-4- hydroxyhydrocinnamate))methane are added for polymer neutralization and stabilization.

[0178] Solvent is flashed off from the reactor effluent, to leave a polymer melt of the Balanced LLDPE. Slip additive (erucamide) and anti-block additive (talc) are added to the polymer melt as shown in Table 4. The polymer melt is pelletized. The properties of the B-LLDPE are shown in Table 4. I-LLDPE

[0179] Two I-LLDPE polymers (I-LLDPE 1 and I-LLDPE 2) are made by solution polymerization in a dual-loop reactor system as described in Kao, et al., US Patent 5,977,251 (2 Nov 1999). The two reactors operate in series.

[0180] The first reactor uses a single site catalysts system that contains the following materials:

[0181] The second reactor uses a catalyst system that includes Ziegler-Natta catalyst and triethylaluminum (TEAL) cocatalyst, which is prepared as described for Balanced LLDPE preparation. The molar ratio of cocatalyst to catalyst (Al to Ti ratio) is 4: 1. The primary monomer is ethylene and the comonomer is 1-octene. Raw materials are purified as described for the production of Balanced LLDPE. Each reactor is operated as described for balanced LLDPE, except feeds and reaction conditions are as shown in Table 3. Effluent from Reactor 1 is fed to Reactor 2 without deactivating.

[0182] Table 3

[0183] Effluent from Reactor 2 is allowed to react for 90 seconds before deactivation, polymer stabilization, polymer recovery and pelletization as described for the production of Balanced LLDPE. I-LLDPE 1 and I-LLDPE 2 are recovered and have the properties shown in Table 4.

[0184] Film Production

[0185] LLDPE polymers used in film production are shown in Table 4.

[0186] Table 4

[0187] 1 - Dart and tear strength are measured on test films as described in the Test Methods. Test films for B-LLDPE are 1 mil thick, and other test films are 2 mil thick.

[0188] The R-LLDPE is REVOLOOP™ 70-LL NA post-consumer recycled plastics resin (70% recycled content) and commercially available from The Dow Chemical Company (Midland, MI). It has a density of 0.918 g / cc and melt index (12) of 1.7 dg / min.

[0189] Preparation of Films

[0190] Multilayer blown films are fabricated using a Hosokawa Alpine 7-layer blown film line. The line consists of seven 50mm 30: 1 grooved feed extruders with barrier screws and a 250 mm (9.9 inches) co- extrusion die. The die is machined with the following layer distribution: 15 / 15 / 13 / 14 / 13 / 15 / 15 and is equipped with internal bubble cooling. Each extruder is equipped with a Maguire four-component blender. Ratio of layers is controlled by varying the rate of feed from each extruder to each layer of the die. Film gauge is controlled using an Alpine auto-profde air ring system with NDC Backscatter Gamma sensors. The film fabrication conditions are: film thickness is maintained at 0.9 mil; blow up ratio is 1.9; die gap is 79 mil; frost line height is 30 inch, output rate is 10 lbs. per hour per inch of the circumference of the die, polymer melt temperature is about 210°C. Table 5 shows the polymers used in each film. IE1 and IE2 are examples of the invention. CE1 through CE6 are comparative examples. Table 5 shows the dart impact strength (Dart) in grams and the Elmendorf tear resistance (Machine direction) (Tear) in gram force for each film.

[0191] Table 5A

[0192] Table 5B Inventive films IE1 and IE2 contain more than 20 weight percent post-consumer recycled LLDPE and have balanced tear resistance and impact resistance comparable to virgin monolayer LLDPE of similar thickness.

Claims

CLAIMSWe claim:

1. A multilayer film comprising two face layers and at least one internal layer, wherein the film comprises:(a) at least 20 volume percent of one or more layers, called “T-Layers”, that comprise a first LLDPE polymer, called “T-LLDPE”, having a melt index (12) of 0.2 dg / min to 4.0 dg / min and an MWCDI less than -1.0, and wherein at least one face Layer is a T-Layer;(b) at least 5 volume percent of one or more layers, called “I-Layers”, that comprise a second LLDPE polymer, called “I-LLDPE”, having a melt index (12) of 0.4 dg / min to 4.0 dg / min and an MWCDI greater than 1.0;(c) at least 10 volume percent of one or more layers, called “R-Layers”, that comprise a recycled LLDPE composition, called “R-LLDPE”, that comprises recycled LLDPE polymers;(d) optionally, one or more layers, called “B-Layers”, that comprise a third LLDPE composition, called “B-LLDPE”, having a melt index (12) of 0.4 dg / min to 4.0 dg / min and an MWCDI from -1.0 to 1 .0; and and wherein the film comprises at least 10 weight percent LLDPE recycled polymers, based on the total weight of the film.

2. The multilayer-film of claim 1, which comprises at least four layers and wherein both face layers are T-Layers.

3. The multilayer-film of claim 1, which comprises at least four layers and wherein at least one layer is a B-Layer.

4. The multilayer-film of claim 1, which comprises at least five layers, wherein both face layers are T-Layers and at least one internal layer is a B-Layer.

5. The multilayer film of claim 4, wherein the T-LLDPE has (a) a density of 0.920 g / cc to 0.928 g / cc, (b) a melt index of 0.4 dg / min to 0.7 dg / min, and (c) an MWCDI from -1.5 to -2.5.

6. The multilayer film of claim 5, wherein the T-LLDPE has a weight average molecular weight from 140,000 g / mol to 160,000 g / mol and a molecular weight distribution from 4.5 to 5.5.

7. The multilayer film of claim 4 , wherein the I-LLDPE has (a) a density of 0.910 g / cc to 0.920 g / cc, (b) a melt index of 0.70 dg / min to 1.1 dg / min, and (c) an MWCDI from 2 to 4.

8. The multilayer film of claim 7, wherein the I-LLDPE has a weight average molecular weight from 100,000 g / mol to 130,000 g / mol and a molecular weight distribution from 2.5 to 4.5.

9. The multilayer film of claim 4, wherein the B-LLDPE has (a) a density of 0.916 g / cc to 0.924 g / cc, (b) a melt index of 0.55 dg / min to 0.90 dg / min, and (c) an MWCDI from 0.0 to -1.0.

10. The multilayer film of claim 9, wherein the B-LLDPE has a weight average molecular weight from 120,000 g / mol to 150,000 g / mol and a molecular weight distribution from 4 to 6.

11. The multilayer film of claim 4, wherein:(a) the T-LLDPE has (i) a density of 0.920 g / cc to 0.928 g / cc, (ii) a melt index of 0.4 dg / min to 0.7 dg / min, and (iii) an MWCDI from -1.5 to -2.5; and(b) the I-LLDPE has (i) a density of 0.910 g / cc to 0.920 g / cc, (ii) a melt index of 0.70 dg / min to 1.1 dg / min, and (iii) an MWCDI from 2 to 4; and(c) the B-LLDPE has (i) a density of 0.916 g / cc to 0.924 g / cc, (ii) a melt index of 0.55 dg / min to 0.90 dg / min, and (iii) an MWCDI from 0.0 to -1.0.

12. The multilayer film of claim 11, wherein(a) the T-Layer(s) collectively make up from 25 to 35 volume percent of the multilayer film;(b) the I-Layer(s) collectively make up from 8 to 15 volume percent of the multilayer film;(c) the B-Layer(s) collectively make up from 25 to 35 volume percent of the multilayer film; and(d) the R-Layer(s) collectively make up from 25 to 35 volume percent of the multilayer film.

13. The multilayer film of claim 11 which is a 7-layer film comprising, in order, the following layers:(a) from 10 to 20 volume percent of a first face layer, which is a T-Layer;(b) from 10 to 20 volume percent of a first internal B-Layer;(c) from 10 to 20 volume percent of a first internal R-Layer;(d) from 5 to 15 volume percent of an internal I-Layer;(e) from 10 to 20 volume percent of a second internal R-Layer;(f) from 10 to 20 volume percent of a second internal B-Layer; and(g) from 10 to 20 volume percent of a second face layer, which is a T-Layer.

14. A bag comprising the multilayer film described in any one of claims 1 to 13, which comprises at least 20 weight percent recycled LLDPE polymers.

15. The bag of claim 14, wherein the multilayer film has (a) an average thickness of 0.8 to 1.0 mil;(b) an Elmendorf tear resistance (machine direction) of at least 250 gf; and (c) a dart impact resistance of at least 300 g.

Images