Composition for use in a rotomolding process

Abstract

A thermoplastic composition suitable for use in rotomolding applications comprises a) a polyethylene composition having a melt index, h of from 0.5 to 10 g / 10 min and a density of from 0.930 to 0.965 g / cm3; and b) an additive package. The additive package comprises benzo-furanone antioxidant compound. The polyethylene composition comprises a first polyethylene component which is an ethylene copolymer and a second polyethylene component which is an ethylene homopolymer or an ethylene copolymer; wherein the first polyethylene component has a weight average molecular weight, Mw1 which is higher than a weight average molecular weight, Mw2 of the second polyethylene component.

Description

[0001] COMPOSITION FOR USE IN A ROTOMOLDING PROCESS

[0002] TECHNICAL FIELD

[0003] A thermoplastic composition suitable for use in rotomolding applications comprises a polyethylene composition and an additive package selected to expand the process conditions over which a rotomolded article can be made while maintaining impact properties.

[0004] BACKGROUND ART

[0005] Polyethylene compositions used in rotomolding processes may have relatively short cure times but suffer from a narrow range of processing conditions over which optimal rotomolded part properties can be achieved. For some polyethylene compositions there may be a significant drop in a rotomolded article’s impact strength when molded at intermediate cure times, with the practical effect that the processing window (the range of oven times which can be used during the rotomolding process) of such a polyethylene composition may be relatively narrow. This phenomenon, where high ARM impact properties (i.e. ductile failure and / or mean failure energy) are achieved at relatively short rotomolding cure times, lost at intermediate cure times and then recovered at higher cure times is known to persons skilled in the art as the “impact knee” phenomenon. The deeper and wider the impact knee, the narrower the rotomolding processing window in which to make a rotomolded article having optimized properties. Although rotational molding conditions can be adjusted to avoid the “impact knee” it would be advantageous if the processing window of a given polyethylene composition could be widened so that a broader range of rotomolding processing conditions (a wider range of oven cure times) could be employed while also achieving optimized impact performance metrics for the rotomolded part.

[0006] Benzo-furanone antioxidant compounds are known and have been used to help stabilize polyolefins. Benzo-furanone antioxidant compounds may have the following general formula: wherein R* is each occurrence a hydrocarbyl group, and R is an OH group, a hydrocarbyl group or a heteroatom containing hydrocarbyl group.

[0007] SUMMARY OF INVENTION

[0008] An additive package comprising a benzo-furanone antioxidant compound broadens the processing window over which a rotomolded part made from a thermoplastic composition comprising a polyethylene composition and the additive package can be made while achieving good impact strength of the rotomolded part.

[0009] An embodiment is a thermoplastic composition for use in a rotomolding process, the thermoplastic composition comprising: a) a polyethylene composition having a melt index, L of from 0.5 to 10 g / lOmin and a density of from 0.930 to 0.965 g / cm3, the polyethylene composition comprising: a first polyethylene component which is an ethylene copolymer; and a second polyethylene component which is an ethylene homopolymer or an ethylene copolymer; wherein the first polyethylene component has a weight average molecular weight, Mw1which is higher than a weight average molecular weight, Mw2of the second polyethylene component; and b) an additive package comprising a benzo-furanone antioxidant compound having the formula I: wherein n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; and R3 is independently a Ci-Cs alkyl group or a OH group.

[0010] An embodiment is a rotomolding process for making a rotomolded article, the process comprising: preparing a thermoplastic composition by combining a polyethylene composition with an additive package; adding the thermoplastic composition to a mold; heating the mold; rotating the mold about at least 2 axes of rotation; cooling the mold; and removing the rotomolded article from the mold; wherein the polyethylene composition has a melt index, h of from 0.5 to 10 g / lOmin and a density of from 0.940 to 0.970 g / cm3, and comprises: a first polyethylene component which is an ethylene copolymer; and a second polyethylene component which is an ethylene homopolymer or an ethylene copolymer; wherein the first polyethylene component has a weight average molecular weight, Mw1which is higher than a weight average molecular weight, Mw2of the second polyethylene component; and wherein the additive package comprises a benzo-furanone antioxidant compound having the formula I: wherein n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; and R3 is independently a Ci-Cs alkyl group or a OH group.

[0011] In an embodiment, the benzo-furanone antioxidant compound has the formula II:

[0012] wherein n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; R4 and Rs are independently a H or a Ci-Cs alkyl group; Re is H or a OH group; and R7 and Rs are independently a H or a Ci-Cs alkyl group. In an embodiment a benzo-furanone antioxidant compound has the formula III:

[0013] In an embodiment, a polyethylene composition has a density of from 0.932 to 0.960 g / cm3, the polyethylene.

[0014] In an embodiment, a polyethylene composition has a melt index, I2 of from 1.0 to lO g / lOmin.

[0015] BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 shows the results of ARM impact testing (-40°C) of 0.25 inch molded parts made with the thermoplastic compositions of the present disclosure as well as for a control polyethylene composition. The rotomolded samples were prepared using an oven temperature of 560°F at the indicated oven times. Figure 1 shows the mean failure energy.

[0017] Figure 2 shows the results of ARM impact testing (-40°C) of 0.25 inch molded parts made with the thermoplastic compositions of the present disclosure as well as for a control polyethylene composition. The rotomolded samples were prepared using an oven temperature of 560°F at the indicated oven times. Figure 2 shows the ductility.

[0018] Figure 3 shows the yellowness index (“YI” index) for the outside surface of molded parts made with the thermoplastic compositions of the present disclosure. The rotomolded samples were prepared using an oven temperature of 560°F at the indicated oven times.

[0019] DESCRIPTION OF EMBODIMENTS

[0020] As used herein, the term “monomer” refers to a small molecule that may chemically react and become chemically bonded with itself or other monomers to form a polymer.

[0021] As used herein, the term “a -olefin” or “alpha-olefin” is used to describe a monomer having a linear hydrocarbon chain containing from 3 to 20 carbon atoms having a double bond at one end of the chain; an equivalent term is “linear a-olefin”. An alpha-olefin may also be referred to as a comonomer.

[0022] An “alkoxy group” is an oxy group having an alkyl group pendant there from; and includes for example a methoxy group, an ethoxy group, an iso-propoxy group, and the like. An “arylalkyloxy group” is an oxy group having an arylalkyl group pendent there from (for clarity, the alkyl moiety is bonded to the oxy moiety and the aryl group is bonded to the alkyl moiety).

[0023] An “aryloxy” group is an oxy group having an aryl group pendant there from; and includes for example a phenoxy group and the like. An “alkylaryloxy group” is an oxy group having an alkylaryl group pendent there from (for clarity, the aryl moiety is bonded to the oxy moiety and the alkyl group is bonded to the aryl moiety).

[0024] In the present disclosure, a thermoplastic composition which is useful in the formation of rotomolded articles, comprises a polyethylene composition and a specifically defined additive package which improves the performance of the polyethylene composition in a rotomolding process.

[0025] In an embodiment an additive package comprises a benzo-furanone antioxidant compound.

[0026] In an embodiment, the benzo-furanone antioxidant compound has the formula I:

[0027] wherein n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; and R3 is independently a Ci-Cs alkyl group or a OH group.

[0028] In an embodiment, the benzo-furanone antioxidant compound has the formula II: wherein n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; R4 and Rs are independently a H or a Ci-Cs alkyl group; Re is H or a OH group; and R7 and Rs are independently a H or a Ci-Cs alkyl group. In an embodiment, in the formula II, n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; R4 is H and Rs is a Ci-Cs alkyl group; Re is H or a OH group; R7 is a Ci-Cs alkyl group; and Rs is H. In an embodiment, in the formula II, n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; R4 is H and Rs is a Ci-Cs alkyl group; Re is a OH group; R7 is a Ci-Cs alkyl group; and Rs is H. In an embodiment, in the formula II, n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; R4 is H and Rs is a C3-C5 alkyl group; Re is a OH group; R7 is a C3-C5 alkyl group; and Rs is H. In an embodiment, in the formula II, n = 0; Ri and R2 are independently a Ci-Cs alkyl group; R4 is H and Rs is a C3-C5 alkyl group; Re is a OH group; R7 is a C3-C5 alkyl group; and Rs is H. In further specific embodiments, the benzo-furanone antioxidant compound can be any benzo-furanone antioxidant compound disclosed in U.S. Pat. No. 8,840,810 including a benzo-furanone antioxidant compound selected from the group consisting of [4-tert-butyl-2- (5-tert-butyl-2-oxo-3H-benzofuran-3-yl)phenyl]benzoate; [4-tert-butyl-2-(5-tert-butyl-2- oxo-3H-benzofuran-3-yl)phenyl]-3,5-di(tert-butyl)-4-hydroxy-benzoate; [4-tert-butyl-2-(5- tert-butyl-2-oxo-3H-benzofuran-3 -yl)phenyl] -3 -[3 ,5 -di(tert-butyl)-4-hydroxy-phenyl] - propanoate; and mixtures thereof.

[0029] In an embodiment, the benzo-furanone antioxidant compound has the formula III:

[0030] The benzo-furanone antioxidant compound having the formula III may be named [4- tert-butyl-2-(5-tert-butyl-2-oxo-3H-benzofuran-3-yl)phenyl]-3,5-di(tert-butyl)-4-hydroxy- benzoate and is commercially available from the Chitec Technology Company under the tradename REVONOX® 501.

[0031] The benzo-furanone antioxidant compound can be added to a polyethylene composition during an extrusion or compounding step, but other suitable known methods will be apparent to a person skilled in the art. The benzo-furanone antioxidant compound can be added as is or as part of a separate polymer component added during an extrusion or compounding step.

[0032] In an embodiment of the disclosure, the benzo-furanone antioxidant compound may be added to the polyethylene composition by way of a “masterbatch”, where the term “masterbatch” refers to the practice of first melt mixing the additive (e.g., benzo-furanone antioxidant compound) with a small amount of the polyethylene composition, followed by melt mixing the “masterbatch” with the remaining bulk of the polyethylene composition. In an embodiment of the disclosure, the amount of the benzo-furanone antioxidant compound combined with a polyethylene composition will be from 50 to 4,000 parts per million by weight (based on the weight of the polyethylene composition) including any sub range within this range and any value within this range. Further optimized levels and ranges for a given rotomolding process may be readily determined by those skilled in the art. For example, in certain embodiments, the amount of benzo-furanone antioxidant compound combined with a polyethylene composition will be from 50 to 4,000 parts per million by weight, or 100 to 4,000 parts per million by weight, or 200 to 4,000 parts per million by weight, or from 100 to 3,000 parts per million by weight, or from 200 to 3,000 parts per million by weight, or from 100 to 2,000 parts per million by weight, or from 200 to 2,500 parts per million by weight, or from 300 to 2,500 parts per million by weight, or from 300 to 2,500 parts per million by weight, or from 400 to 2,500 parts per million by weight, or from 500 to 2,500 parts per million by weight, or from 750 to 4,000 parts per million by weight, or from 750 to 3,000 parts per million by weight, or from 750 to 2,500 parts per million by weight, or from 1,000 to 4,000 parts per million by weight, or from 1,000 to 3,000 parts per million by weight, or from 1,000 to 2,500 parts per million by weight, or from 1,000 to 2,250 parts per million by weight, or from 1,000 to 2,000 parts per million by weight, or from 1,250 to 1,750 parts per million by weight, or from 500 to 2,250 parts per million by weight, or from 500 to 2,000 parts per million by weight, or from 300 to 2,000 parts per million by weight, or from 200 to 2,000 parts per million by weight, or from 200 to 1,500 parts per million by weight, or from 200 to 1,000 parts per million by weight, or from 200 to 750 parts per million by weight, or from 200 to 500 parts per million by weight, or from 100 to 500 parts per million by weight, or from 100 to 400 parts per million by weight, or from 100 to 300 parts per million by weight, or from 50 to 300 parts per million by weight, or from 50 to 250 parts per million by weight, or from 50 to 200 parts per million by weight, where parts per million (ppm) by weight is based on the weight of the polyethylene composition.

[0033] In an embodiment of the disclosure, the benzo-furanone antioxidant compound is added to a polyethylene composition using a masterbatch formulation containing the first hindered phenolic antioxidant compound. The term masterbatch is well known to persons skilled in the art. Generally, the term “masterbatch” refers to the practice of first melt mixing an additive with a small amount of a given polymer, followed by blending (by for example melt mixing or dry blending) the resulting “masterbatch” with the remaining bulk of the polymer. In embodiments of the disclosure, from about 0.1 to about 15.0 weight percent, or from about 0.5 to about 15.0 weight percent, or from about 0.5 to about 10.0 weight percent, or from about 0. 1 to about 10.0 weight percent, or from about 0.1 to about 7.5 weight percent, or from about 0.5 to about 7.5 weight percent or from about 0.5 to about 5.0 weight percent, or from about 0.1 to about 5.0 weight percent, or from about 1.0 to about 15.0 weight percent, or from about 1.0 to about 5.0 weight percent, or from about 1.0 to about 7.5 weight percent, or from about 1.0 to about 5.0 weight percent, or from about 0.1 to about 2.5 weight percent, or from about 0.5 to about 2.5 weight percent of a masterbatch will be used in a blend with the bulk polymer (where weight percent of the masterbatch is based on the combined weight of the masterbatch and the bulk polymer).

[0034] In embodiments of the present disclosure, a masterbatch of a polyethylene composition may contain an amount of benzo-furanone antioxidant compound in the range of from 500 to 50,000 parts per million by weight (based on the weight of the masterbatch) including subranges within this range and any number within this range. For example, in further embodiments of the disclosure, a masterbatch may contain an amount of benzo- furanone antioxidant compound in the range of from 500 to 40,000 ppm, or from 500 to 35,000 ppm, or from 500 to 40,000 ppm, or from 500 to 25,000 ppm, or from 1,000 to 40,000 ppm, or from 1,000 to 35,000 ppm, or from 1,000 to 30,000 ppm, or from 1,000 to 25,000 parts per million by weight (based on the weight of the masterbatch), or from 5,000 to 25,000 ppm, or from 1,000 to 20,000 ppm, or from 2,000 to 20,000 ppm, or from 3,000 to 20,000, or from 4,000 to 20,000 ppm, or from 5,000 to 20,000 ppm, or from 5,000 to 17,500, or from 5,000 to 15,000 or from 5,000 to 12,500 ppm, or from 2,500 to 15,000 ppm, or from 5,000 to 15,000 ppm, or from 7,500 to 15,000 ppm, or from 7,500 ppm to 12,500 ppm, or from 5,000 to 50,000 ppm, or from 7,500 to 50,000 ppm, or from 10,000 to 50,000 ppm, or from 10,000 to 35,000 ppm, or from 10,000 to 25,000 ppm, or from 5,000 to 35,000 ppm, or from 5,000 to 30,000 ppm, or from 5,000 to 25,000 ppm, or from 15,000 to 30,000 ppm, or from 17,500 to 27,500 ppm, or from 20,000 to 25,000 ppm.

[0035] The benzo-furanone antioxidant compound may be used in the form of a semi solid or a viscous liquid, or as powders, pellets, or granules.

[0036] The Polyethylene Composition

[0037] In an embodiment of the disclosure, the polyethylene composition has a melt index, h of from 0.5 to 10 g / lOmin and a density of from 0.930 to 0.965 g / cm3. In an embodiment of the disclosure, the polyethylene composition comprises a first polyethylene component and a second polyethylene component which is different from the first polyethylene component.

[0038] In an embodiment of the disclosure, the polyethylene composition comprises a first polyethylene component which is an ethylene copolymer; and a second polyethylene component which is an ethylene homopolymer or an ethylene copolymer; wherein the first polyethylene component has a weight average molecular weight, Mw1which is higher than a weight average molecular weight, Mw2of the second polyethylene component.

[0039] In an embodiment of the disclosure, the polyethylene composition will comprise a first polyethylene component and a second polyethylene component, each as defined further below.

[0040] The polyethylene compositions disclosed herein can be made using any well-known techniques in the art, including but not limited to melt blending, solution blending, or inreactor blending to bring together a polyethylene component and a polyethylene component.

[0041] In an embodiment, the polyethylene component of the present disclosure is made using a single site catalyst in a first reactor to give a first polyethylene component, and a single site catalyst in a second reactor to give a second polyethylene component.

[0042] In an embodiment, the polyethylene composition of the present disclosure is made by forming a first polyethylene component in a first reactor by polymerizing ethylene and an a-olefin with a single site catalyst; and forming a second polyethylene component in a second reactor by polymerizing ethylene and an a-olefin with a single site catalyst.

[0043] In an embodiment, the polyethylene composition of the present disclosure is made by forming a first polyethylene component in a first solution phase polymerization reactor by polymerizing ethylene and an a-olefin with a single site catalyst; and forming a second polyethylene component in a second solution phase polymerization reactor by polymerizing ethylene and an a-olefin with a single site catalyst.

[0044] In an embodiment, the polyethylene composition of the present disclosure is made by forming a first polyethylene component in a first solution phase polymerization reactor by polymerizing ethylene and a-olefin with a single site catalyst; and forming a second polyethylene component in a second solution phase polymerization reactor by polymerizing ethylene and an a-olefin with a single site catalyst, where the first and second solution phase polymerization reactors are configured in series with one another. In an embodiment, the polyethylene composition of the present disclosure is made by forming a first polyethylene component in a first solution phase polymerization reactor by polymerizing ethylene and a-olefm with a single site catalyst; and forming a second polyethylene component in a second solution phase polymerization reactor by polymerizing ethylene and an a-olefm with a single site catalyst, where the first and second solution phase polymerization reactors are configured in parallel to one another.

[0045] In an embodiment, the polyethylene composition of the present disclosure is made by forming a first polyethylene component in a first reactor by polymerizing ethylene and an a-olefm with a single site catalyst; and forming a second polyethylene component in a second reactor by polymerizing ethylene with a single site catalyst.

[0046] In an embodiment, the polyethylene composition of the present disclosure is made by forming a first polyethylene component in a first solution phase polymerization reactor by polymerizing ethylene and an a-olefm with a single site catalyst; and forming a second polyethylene component in a second solution phase polymerization reactor by polymerizing ethylene with a single site catalyst.

[0047] In an embodiment, the polyethylene composition of the present disclosure is made by forming a first polyethylene component in a first solution phase polymerization reactor by polymerizing ethylene and a-olefm with a single site catalyst; and forming a second polyethylene component in a second solution phase polymerization reactor by polymerizing ethylene with a single site catalyst, where the first and second solution phase polymerization reactors are configured in series with one another.

[0048] In an embodiment, the bimodal polyethylene composition of the present disclosure is made by forming a first polyethylene component in a first solution phase polymerization reactor by polymerizing ethylene and a-olefm with a single site catalyst; and forming a second polyethylene component in a second solution phase polymerization reactor by polymerizing ethylene with a single site catalyst, where the first and second solution phase polymerization reactors are configured in parallel to one another.

[0049] In embodiments, the solution phase polymerization reactor used as a first solution phase reactor is a continuously stirred tank reactor or a tubular reactor.

[0050] In an embodiment, the solution phase polymerization reactor used as a second solution phase reactor is a continuously stirred tank reactor or a tubular reactor.

[0051] In solution polymerization, the monomers are dissolved / dispersed in the solvent either prior to being fed to the reactor (or for gaseous monomers the monomer may be fed to the reactor so that it will dissolve in the reaction mixture). Prior to mixing, the solvent and monomers are generally purified to remove potential catalyst poisons such as water, oxygen or metal impurities. The feedstock purification follows standard practices in the art, e.g. molecular sieves, alumina beds and oxygen removal catalysts are used for the purification of monomers. The solvent itself as well (e.g. methyl pentane, cyclohexane, hexane or toluene) is preferably treated in a similar manner.

[0052] The feedstock may be heated or cooled prior to feeding to the reactor.

[0053] Generally, the catalyst components may be premixed in the solvent for the reaction or fed as separate streams to the reactor. In some instances, catalyst components premixing may be desirable to provide a reaction time for the catalyst components prior to entering the polymerization reaction zone. Such an “in line mixing” technique is well known to persons skilled in the art.

[0054] Solution polymerization processes for the polymerization or copolymerization of ethylene are well known in the art (see for example, U.S. Pat. Nos. 6,372,864 and 6,777,509). These processes are conducted in the presence of an inert hydrocarbon solvent. In a solution phase polymerization reactor, a variety of solvents may be used as the process solvent; non-limiting examples include linear, branched or cyclic Cs to C12 alkanes. Suitable catalyst component solvents include aliphatic and aromatic hydrocarbons. Nonlimiting examples of aliphatic catalyst component solvents include linear, branched or cyclic C5-12 aliphatic hydrocarbons, e.g. pentane, methyl pentane, hexane, heptane, octane, cyclohexane, cyclopentane, methylcyclohexane, hydrogenated naphtha or combinations thereof. Non-limiting examples of aromatic catalyst component solvents include benzene, toluene (methylbenzene), ethylbenzene, o-xylene (1,2-dimethylbenzene), m-xylene (1,3- dimethylbenzene), p-xylene (1,4-dimethylbenzene), mixtures of xylene isomers, hemellitene (1,2,3-trimethylbenzene), pseudocumene (1,2,4-trimethylbenzene), mesitylene (1,3,5- trimethylbenzene), mixtures of trimethylbenzene isomers, prehenitene (1, 2,3,4- tetramethylbenzene), durene (1,2,3,5-tetramethylbenzene), mixtures of tetramethylbenzene isomers, pentamethylbenzene, hexamethylbenzene and combinations thereof.

[0055] The polymerization temperature in a conventional solution process may be from about 80°C to about 300°C. In an embodiment of the disclosure the polymerization temperature in a solution process is from about 120°C to about 250°C. The polymerization pressure in a solution process may be a “medium pressure process”, meaning that the pressure in the reactor is less than about 6,000 psi (about 42,000 kiloPascals or kPa). In an embodiment of the disclosure, the polymerization pressure in a solution process may be from about 10,000 to about 40,000 kPa, or from about 14,000 to about 22,000 kPa (i.e. from about 2,000 psi to about 3,000 psi).

[0056] Suitable comonomers (i.e. a-olefms) for copolymerization with ethylene in a solution phase polymerization process include C3-20 mono- and di-olefins. In embodiments of the disclosure, comonomers which may be copolymerized with ethylene include C3-12 a- olefins which are unsubstituted or substituted by up to two C1-6 alkyl radicals, Cs-12 vinyl aromatic monomers which are unsubstituted or substituted by up to two substituents selected from the group consisting of C1-4 alkyl radicals, C4-12 straight chained or cyclic diolefms which are unsubstituted or substituted by a C1-4 alkyl radical. In further embodiments of the disclosure, a-olefms which may be copolymerized with ethylene are one or more of propylene, 1 -butene, 1 -pentene, 1 -hexene, 1 -octene and 1 -decene, styrene, alpha methyl styrene, and the constrained-ring cyclic olefins such as cyclobutene, cyclopentene, dicyclopentadiene norbomene, alkyl-substituted norbomenes, alkenylsubstituted norbomenes and the like (e.g. 5-methylene-2-norbomene and 5-ethylidene-2- norbomene, bicyclo-(2,2, 1 )-hepta-2,5 -diene) .

[0057] In an embodiment of the disclosure, the polyethylene composition comprises polymerized ethylene and one or more than one alpha olefin selected from the group comprising 1 -butene, 1 -hexene, 1 -octene and mixtures thereof.

[0058] In an embodiment of the disclosure, the polyethylene composition comprises polymerized ethylene and one or more than one alpha olefin selected from the group comprising 1 -hexene, 1 -octene and mixtures thereof.

[0059] In an embodiment of the disclosure, the polyethylene composition comprises polymerized ethylene and 1 -octene.

[0060] In an embodiment of the disclosure, the polyethylene composition has from 0. 1 to 7.5 mole percent of one or more than one a-olefin, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the polyethylene composition has from 0. 1 to 5.0 mole percent of one or more than one a-olefin, or from 0.1 to 3.0 mole percent of one or more than one a-olefin, or from 0.5 to 5.0 mole percent of one or more than one a-olefin, or from 0.5 to 3 mole percent of one or more than one a-olefin, or from 0.1 to 2.5 mole percent of one or more than one a-olefin, or from 0.1 to 2.0 mole percent of one or more than one a-olefin, or from 0.5 to 2.0 mole percent of one or more than one a-olefin, or from 0. 1 to 2.0 mole percent of one or more than one a-olefin, or from 0. 1 to 1.5 mole percent of one or more than one a- olefin, or from 0. 1 to 1.0 mole percent of one or more than one a-olefin

[0061] In embodiments of the disclosure, the polyethylene composition has from 0.1 to 5.0 mole percent of 1-octene, or from 0.1 to 3.0 mole percent of 1-octene, or from 0.5 to 5.0 mole percent of 1-octene, or from 0.5 to 3 mole percent of 1-octene, or from 0.1 to 2.5 mole percent of 1-octene, or from 0. 1 to 2.0 mole percent of 1-octene, or from 0.5 to 2.0 mole percent of 1-octene, or from 0.1 to 1.5 mole percent of 1-octene, or from 0.1 to 1.0 mole percent of 1-octene.

[0062] In embodiments of the disclosure where the polyethylene composition comprises a first polyethylene component and a second polyethylene component (as defined above), the polyethylene composition may have a ratio (SCB1 / SCB2) of the number of short chain branches per thousand carbon atoms in the first polyethylene component (i.e., SCB1) to the number of short chain branches per thousand carbon atoms in the second polyethylene component (i.e., SCB2) of at least 5.0 (i.e., SCB1 / SCB2 > 5.0). In further embodiments of the disclosure, the ratio of the short chain branching in the first polyethylene component (SCB1) to the short chain branching in the second polyethylene component (SCB2) is at least 7.5 or greater than 7.5, or at least 10.0 or greater than 10.0, or at least 25.0 or greater than 25.0, or at least 50.0 or greater than 50.0, or at least 100.0 or greater than 100.0. In still further embodiments of the disclosure, the ratio of the short chain branching in the first polyethylene component (SCB1) to the short chain branching in the second polyethylene component (SCB2) is from about 5 to about 500, or from about 10 to about 500, or from about 50 to about 500, or from about 100 to about 500, or from about 250 to about 350.

[0063] In an embodiment of the disclosure, the polyethylene composition has a weight average molecular weight, Mwof < 100,000 g / mol, or < 95,000 g / mol, or < 90,000 g / mol, or < 85,000 g / mol, or < 100,000 g / mol, or < 95,000 g / mol, or < 90,000 g / mol, or < 85,000 g / mol.

[0064] In embodiments of the disclosure, the polyethylene composition has a weight average molecular weight, Mwof from 30,000 to 150,000 g / mol, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the polyethylene composition has a weight average molecular weight, Mwof from 30,000 to 125,000 g / mol, or from 35,000 to 100,000 g / mol, or from 40,000 to 90,000 g / mol, or from 50,000 to 90,000 g / mol. In an embodiment of the disclosure, the polyethylene composition has a number average molecular weight, Mnof < 60,000 g / mol, or < 50,000 g / mol, or < 50,000 g / mol, or

[0065] < 45,000 g / mol, or < 45,000 g / mol, or < 40,000 g / mol, or < 40,000 g / mol, or < 35,000 g / mol, or < 35,000 g / mol. In further embodiments of the disclosure, the polyethylene composition has a number average molecular weight, Mnof from 5,000 to 60,000 g / mol, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the polyethylene composition has a number average molecular weight, Mnof from 10,000 to 55,000 g / mol, or from 10,000 to 50,000 g / mol, or from 15,000 to 50,000 g / mol, or from 15,000 to 45,000 g / mol, or from 15,000 to 40,000 g / mol, or from 15,000 to 35,000 g / mol.

[0066] In an embodiment of the disclosure, the polyethylene composition has a Z-average molecular weight, Mz, of < 250,000 g / mol, or < 225,000 g / mol, or < 200,000 g / mol, or

[0067] < 250,000 g / mol, or < 225,000 g / mol, or < 200,000 g / mol.

[0068] In further embodiments of the disclosure, the polyethylene composition has a Z- average molecular weight, Mzof from 125,000 to 300,000 g / mol, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the polyethylene composition has a Z-average molecular weight, Mz of from 125,000 to 275,000 g / mol, or from 125,000 to 250,000 g / mol, or from 125,000 to 225,000 g / mol, or from 125,000 g / mol to 200,000 g / mol, or from 125,000 to 190,000 g / mol, or from 150,000 g / mol to 200,000 g / mol, or from 150,000 g / mol to 175,000 g / mol.

[0069] In an embodiment of the disclosure, the polyethylene copolymer composition has a bimodal profde (i.e. a bimodal molecular weight distribution) in a gel permeation chromatography (GPC) analysis.

[0070] In an embodiment of the disclosure, the polyethylene copolymer composition has a bimodal profde in a gel permeation chromatograph generated according to the method of ASTM D6474-99.

[0071] In an embodiment of the disclosure, the polyethylene copolymer composition has a unimodal profde (i.e. a bimodal molecular weight distribution) in a gel permeation chromatography (GPC) analysis.

[0072] In an embodiment of the disclosure, the polyethylene copolymer composition has a unimodal profde in a gel permeation chromatograph generated according to the method of ASTM D6474-99. The term “unimodal” is herein defined to mean there will be only one significant peak or maximum evident in the GPC-curve. In contrast, the use of the term “bimodal” is meant to convey that in addition to a first peak, there will be a secondary peak or shoulder which represents a higher or lower molecular weight component (i.e. the molecular weight distribution, can be said to have two maxima in a molecular weight distribution curve). Alternatively, the term “bimodal” connotes the presence of two maxima in a molecular weight distribution curve generated according to the method of ASTM D6474-99. The term “multi-modal” denotes the presence of two or more, typically more than two, maxima in a molecular weight distribution curve generated according to the method of ASTM D6474- 99.

[0073] In embodiments of the disclosure, the polyethylene composition has a molecular weight distribution, Mw / Mnof < 6.0, or < 6.0, or 5.5, or < 5.5, or < 5.0, or < 5.0, or < 4.5, or < 4.5, or < 4.0, or < 4.0, or < 3.5, or < 3.5, or < 3.0, or < 3.0, or < 2.5, or < 2.5. In further embodiments of the disclosure, the polyethylene composition has a molecular weight distribution, Mw / Mnof from 1.7 to 6.0, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the polyethylene composition has a molecular weight distribution, Mw / Mnof from 1.8 to 6.0, or from 1.8 to 5.5, or from 1.8 to 5.0, or from 1.8 to 4.5, or from 1.8 to 4.0, or from 1.8 to 3.5, or from 2.0 to 6.0, or from 2.0 to 5.5, or from 2.0 to 5.0, or from 2.0 to 4.5, or from 2.0 to 4.0, or from 2.0 to 3.5, or from 2.0 to 3.0, or from 2.0 to 2.5.

[0074] In embodiments of the disclosure, the polyethylene copolymer composition has a density of > 0.930 g / cm3, or > 0.936 g / cm3, > 0.940 g / cm3, or > 0.940 g / cm3, or > 0.941 g / cm3, or 0.941 g / cm3.

[0075] In embodiments of the disclosure, the polyethylene composition has a density of from 0.930 to 0.965 g / cm3, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the bimodal polyethylene composition has a density of from 0.930 to 0.960 g / cm3, or from 0.932 to 0.965 g / cm3, or from 0.932 to 0.960 g / cm3, or from 0.934 to 0.965 g / cm3, or from 0.934 to 0.960 g / cm3, or from 0.936 to 0.965 g / cm3, or from 0.936 to 0.960 g / cm3, or from 0.938 to 0.965 g / cm3, or from 0.938 to 0.960 g / cm3, or from 0.939 to 0.965 g / cm3, or from 0.939 to 0.960 g / cm3, or from 0.936 to 0.955 g / cm3, or from 0.938 to 0.955 g / cm3, or from 0.939 to 0.955 g / cm3, or from 0.936 to 0.950 g / cm3, or from 0.938 to 0.950 g / cm3, or from 0.939 to 0.950 g / cm3, or from 0.936 to 0.945 g / cm3, or from 0.938 to 0.945 g / cm3, or from 0.939 to 0.945 g / cm3. In embodiments of the disclosure the polyethylene composition has a melt index, h of at least 1.0 g / lOmin (> 1.0 g / lOmin), or at least 1.5 g / lOmin (> 1.5 g / lOmin), or at least 2.0 g / lOmin (> 2.0 g / lOmin), or greater than 1.0 g / lOmin (> 1.0 g / lOmin), or greater than

[0076] 1.5 g / lOmin (> 1.5 g / lOmin), or greater than 2.0 g / lOmin (> 2.0 g / lOmin). In further embodiments of the disclosure, the polyethylene composition has a melt index, h of from 1.0 to 15.0 g / lOmin, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the melt index, I2 of the polyethylene composition may be from 1.0 to 12.0 g / lOmin, or from 1.0 to lO.O g / lOmin, or from 1.5 to lO.O g / lOmin, or from 2.0 to 12.0 g / 10min, or from 2.0 to 10.0 g / lOmin, or from 2.5 to 10.0 g / lOmin, or from 2.0 to 7.5 g / lOmin, or from 2.5 to 8.0 g / lOmin, or from 2.5 to 7.5 g / lOmin, or from 3.0 to 7.0 g / lOmin, or from 3.0 to 6.0 g / lOmin, or from 3.0 to 5.0 g / lOmin, or from 3.0 to 4.0 g / lOmin, or from 2.0 to 4.0 g / lOmin, or about

[0077] 3.5 g / lOmin.

[0078] In embodiments of the disclosure the polyethylene composition has a high load melt index, I21 of from 30 to 500 g / lOmin, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the high load melt index, I21 of the bimodal polyethylene composition may be from 30 to 250 g / lOmin, or from 50 to 150 g / lOmin, or from 50 to 125 g / lOmin, or from 50 to 100 g / lOmin.

[0079] In embodiments of the disclosure the polyethylene composition has a melt flow ratio, I21 / I2 of < 50, or < 50, or < 45, or < 45, or < 40, or < 40. In further embodiments of the disclosure the polyethylene composition has a melt flow ratio, I21 / I2 of from 15 to 50, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the polyethylene composition has a melt flow ratio, I21 / I2 of from 15 to 45, or from 15 to 40, or from 15 to 35, or from 15 to 30, or from 15 to 25, or from 20 to 30, or from 20 to 25.

[0080] In an embodiment of the disclosure, the polyethylene composition will have a reverse or partially reverse comonomer distribution profile as measured using GPC-FTIR. If the comonomer incorporation decreases with molecular weight, as measured using GPC- FTIR, the distribution is described as “normal”. If the comonomer incorporation is approximately constant with molecular weight, as measured using GPC-FTIR, the comonomer distribution is described as “flat” or “uniform”. The terms “reverse comonomer distribution” and “partially reverse comonomer distribution” mean that in the GPC-FTIR data obtained for a copolymer, there is one or more higher molecular weight components having a higher comonomer incorporation than in one or more lower molecular weight components. The term “reverse(d) comonomer distribution” is used herein to mean, that across the molecular weight range of an ethylene copolymer, comonomer contents for the various polymer fractions are not substantially uniform and the higher molecular weight fractions thereof have proportionally higher comonomer contents (i.e. if the comonomer incorporation rises with molecular weight, the distribution is described as “reverse” or “reversed”). Where the comonomer incorporation rises with increasing molecular weight and then declines, the comonomer distribution is still considered “reverse”, but may also be described as “partially reverse”. A partially reverse comonomer distribution will exhibit a peak or maximum.

[0081] In an embodiment of the disclosure the polyethylene composition has a reversed comonomer distribution profile as measured using GPC-FTIR.

[0082] In an embodiment of the disclosure the polyethylene composition has a partially reversed comonomer distribution profile as measured using GPC-FTIR.

[0083] In embodiments of the disclosure, the polyethylene composition has a CDBLo of from about 70 to about 95 weight%, or from about 70 to about 90 wt%, or from about 75 to about 95 wt%, or from about 75 to about 90 wt%, or from about 80 to about 90 wt%.

[0084] In embodiments of the disclosure, the polyethylene composition or a plaque made from the bimodal polyethylene composition has an environmental stress crack resistance, ESCR at condition A in 100% IGEPAL® CO-630 of greater than 250 hours, or greater than 300 hours, or greater than 350 hours, or greater than 400 hours.

[0085] In embodiments of the disclosure, the polyethylene composition or a plaque made from the bimodal polyethylene composition has an environmental stress crack resistance, ESCR at condition A in 10% IGEPAL CO-630 of greater than 10 hours, or greater than 15 hours, or greater than 20 hours.

[0086] In embodiments of the disclosure, the polyethylene composition or a plaque made from the bimodal polyethylene composition has an environmental stress crack resistance, ESCR at condition B in 100% IGEPAL CO-630 of greater than 700 hours, or greater than 800 hours, or greater than 900 hours, or greater than 1000 hours.

[0087] In embodiments of the disclosure, the polyethylene composition or a plaque made from the bimodal polyethylene composition has an environmental stress crack resistance, ESCR at condition B in 10% IGEPAL CO-630 of greater than 10 hours, or greater than 20 hours, or greater than 25 hours. In embodiments of the disclosure, the polyethylene composition or a plaque made from the bimodal polyethylene composition has an environmental stress crack resistance, ESCR determined at both condition A and at condition B, in 100% IGEPAL CO-630, of greater than 250 hours, or greater than 300 hours, or greater than 350 hours, or greater than 400 hours.

[0088] In embodiments of the disclosure, the polyethylene composition has a zero shear viscosity, rjo at 190°C of from about 750 Pa. s to about 5000 Pa.s, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the polyethylene composition has a zero shear viscosity, rjo at 190°C of from about 1000 Pa.s to about 4500 Pa.s, or from about 1000 Pa.s to about 4000 Pa.s, or from about 1000 Pa.s to about 3500 Pa.s, or from about 1000 Pa.s to about 3000 Pa.s, or from about 1500 Pa.s to about 3500 Pa.s, or from about 1750 Pa.s to about 3500 Pa.s, or from about 2000 Pa.s to about 3500 Pa.s, or from about 2000 Pa.s to about 3000 Pa.s.

[0089] In embodiments of the disclosure, the polyethylene composition has a melt strength of at least 0.6 cN, or at least 0.7 cN, or at least 0.8 cN, or at least 0.85 cN.

[0090] In embodiments of the disclosure, the polyethylene composition or a plaque made from the polyethylene composition has a flexural secant modulus at 1%, of at least 750 MPa, or greater than 750 MPa, or at least 800 MPa, or greater than 800 MPa, or at least 850 MPa, or greater than 850 MPa. In further embodiments of the disclosure the polyethylene composition has a flexural secant modulus at 1% of from 750 to 1200 MPa, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the polyethylene composition has a flexural secant modulus at 1% of from 800 to 1100 MPa, or from 850 to 1050 MPa, or from 850 to 1000 MPa.

[0091] In embodiments of the disclosure, the polyethylene composition or a plaque made from the polyethylene composition has a tensile secant modulus at 1%, of at least 750 MPa, or greater than 750 MPa, or at least 800 MPa, or greater than 800 MPa, or at least 850 MPa, or greater than 850 MPa, or at least 900 MPa, or greater than 900 MPa, or at least 950 MPa. In further embodiments of the disclosure the polyethylene composition has a tensile secant modulus at 1% of from 750 to 1200 MPa, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the polyethylene composition has a tensile secant modulus at 1% of from 800 to 1100 MPa, or from 850 to 1050 MPa, or from 850 to 1000 MPa, or from 900 to 1100 MPa, or from 900 to 1050 MPa.

[0092] In embodiments of the disclosure, the polyethylene composition or a plaque made from the polyethylene composition has an Tensile Impact strength of > 140 foot.pound / inch2, or > 150 foot.pound / inch2, or > 170 foot.pound / inch2. In embodiments of the disclosure, the polyethylene composition or a plaque made from the polyethylene composition has an Tensile Impact strength of from 140 to 225 foot.pound / inch2, or from 150 to 200 foot.pound / inch2, or from 160 to 200 foot.pound / inch2, or from 160 to 190 foot.pound / inch2.

[0093] The First Polyethylene Component

[0094] In an embodiment of the disclosure the first polyethylene component is an ethylene copolymer comprising both polymerized ethylene and at least one polymerized a-olefin comonomer, with polymerized ethylene being the majority species.

[0095] In embodiments of the disclosure, a-olefins which may be copolymerized with ethylene to make the first polyethylene component may be selected from the group comprising 1 -propene, 1 -butene, 1 -pentene, 1 -hexene and 1 -octene and mixtures thereof.

[0096] In an embodiment of the disclosure, the first ethylene copolymer is made with a single site catalyst, non-limiting examples of which include phosphinimine catalysts, metallocene catalysts, and constrained geometry catalysts, all of which are well known in the art.

[0097] In an embodiment of the disclosure the first polyethylene component is made using a single site polymerization catalyst in a solution phase polymerization process.

[0098] In an embodiment of the disclosure, the first polyethylene component is an ethylene / 1 -octene copolymer.

[0099] In an embodiment of the disclosure, the first polyethylene component is made with a phosphinimine catalyst.

[0100] In an embodiment of the disclosure, the first polyethylene component is made with a phosphinimine catalyst having the formula I:

[0101] (LA)aM(PI)b(Q)n (I) wherein (LA) represents is cyclopentadienyl-type ligand; M represents a metal atom selected from the group consisting of Ti, Zr, and Hf; PI represents a phosphinimine ligand; Q represents an activatable ligand as already defined above; a is 0 or 1; b is 1 or 2; (a+b) = 2; n is 1 or 2, and; the sum of (a+b+n) equals the valance of the metal M. As used herein, the term “cyclopentadienyl-type” ligand is meant to include ligands which contain at least one five-carbon ring which is bonded to the metal via eta-5 (or in some cases eta-3) bonding. Thus, the term “cyclopentadienyl-type” includes, for example, unsubstituted cyclopentadienyl, singly or multiply substituted cyclopentadienyl, unsubstituted indenyl, singly or multiply substituted indenyl, unsubstituted fluorenyl and singly or multiply substituted fluorenyl. Hydrogenated versions of indenyl and fluorenyl ligands are also contemplated for use in the current disclosure, so long as the five-carbon ring which bonds to the metal via eta-5 (or in some cases eta-3) bonding remains intact. Substituents for a cyclopentadienyl ligand, an indenyl ligand (or hydrogenated version thereof) and a fluorenyl ligand (or hydrogenated version thereof) may be selected from the group consisting of a C1-30 hydrocarbyl radical (which hydrocarbyl radical may be unsubstituted or further substituted by for example a halide and / or a hydrocarbyl group; for example a suitable substituted C1-30 hydrocarbyl radical is a pentafluorobenzyl group such as -CH2C6F5); a halogen atom; a C1-8 alkoxy radical; a Ce-io aryl or aryloxy radical (each of which may be further substituted by for example a halide and / or a hydrocarbyl group); an amido radical which is unsubstituted or substituted by up to two C1-8 alkyl radicals; a phosphide radical which is unsubstituted or substituted by up to two C1-8 alkyl radicals; a silyl radical of the formula -Si(R')3 wherein each R' is independently selected from the group consisting of hydrogen, a C1-8 alkyl or alkoxy radical, Ce-io aryl or aryloxy radicals; and a germanyl radical of the formula -Ge(R')3 wherein R' is as defined directly above.

[0102] The phosphinimine ligand, PI, is defined by formula:

[0103] (Rp)3P = N - wherein the Rpgroups are independently selected from: a hydrogen atom; a halogen atom; C1-20 hydrocarbyl radicals which are unsubstituted or substituted with one or more halogen atom(s); a C1-8 alkoxy radical; a Ce-io aryl radical; a Ce-io aryloxy radical; an amido radical; a silyl radical of formula -Si(Rs)3, wherein the Rsgroups are independently selected from, a hydrogen atom, a C1-8 alkyl or alkoxy radical, a Ce-io aryl radical, a Ce-io aryloxy radical, or a germanyl radical of formula -Ge(RG)3, wherein the RGgroups are defined as Rsis defined in this paragraph.

[0104] In an embodiment of the disclosure, the metal, M in the phosphinimine catalyst is titanium, Ti. In an embodiment of the disclosure, the single site catalyst used to make the first polyethylene component is cyclopentadienyl tri(tertiarybutyl)phosphinimine titanium dichloride, Cp((t-Bu)3PN)TiCh.

[0105] In addition to the single site catalyst molecule per se, an active single site catalyst system may further comprise one or more of the following: an alkylaluminoxane co-catalyst and an ionic activator. The single site catalyst system may also optionally comprise a hindered phenol.

[0106] Although the exact structure of alkylaluminoxane is uncertain, subject matter experts generally agree that it is an oligomeric species that contain repeating units of the general formula:

[0107] (R)2A1O-(A1(R)-O)n-A1(R)2where the R groups may be the same or different linear, branched or cyclic hydrocarbyl radicals containing 1 to 20 carbon atoms and n is from 0 to about 50. A non-limiting example of an alkylaluminoxane is methylaluminoxane (or MAO) wherein each R group is a methyl radical.

[0108] In an embodiment of the disclosure, Rof the alkylaluminoxane, is a methyl radical and m is from 10 to 40.

[0109] In an embodiment of the disclosure, the co-catalyst is modified methylaluminoxane (MMAO).

[0110] It is well known in the art, that the alkylaluminoxane can serve dual roles as both an alkylator and an activator. Hence, an alkylaluminoxane co-catalyst is often used in combination with activatable ligands such as halogens.

[0111] In general, ionic activators are comprised of a cation and a bulky anion; wherein the latter is substantially non-coordinating. Non-limiting examples of ionic activators are boron ionic activators that are four coordinate with four ligands bonded to the boron atom. Nonlimiting examples of boron ionic activators include the following formulas shown below: [R8]+[B(R9)4]- where B represents a boron atom, R8is an aromatic hydrocarbyl (e.g. triphenyl methyl cation) and each R9is independently selected from phenyl radicals which are unsubstituted or substituted with from 3 to 5 substituents selected from fluorine atoms, Ci-4 alkyl or alkoxy radicals which are unsubstituted or substituted by fluorine atoms; and a silyl radical of formula -Si(R10)3, where each R10is independently selected from hydrogen atoms and Ci-4 alkyl radicals, and

[0112] [(Rn)tZH]+[B(R9)4]- where B is a boron atom, H is a hydrogen atom, Z is a nitrogen or phosphorus atom, t is 2 or 3 and R11is selected from Ci-8 alkyl radicals, phenyl radicals which are unsubstituted or substituted by up to three Ci-4 alkyl radicals, or one R11taken together with a nitrogen atom (when Z is nitrogen) may form an anilinium radical and R9is as defined above.

[0113] In both formula a non-limiting example of R9is a pentafluorophenyl radical. In general, boron ionic activators may be described as salts of tetra(perfluorophenyl) boron; non-limiting examples include anilinium, carbonium, oxonium, phosphonium and sulfonium salts of tetra(perfluorophenyl)boron with anilinium and trityl (or triphenylmethylium). Additional non-limiting examples of ionic activators include: triethylammonium tetra(phenyl)boron, tripropylammonium tetra(phenyl)boron, tri(n- butyl)ammonium tetra(phenyl)boron, trimethylammonium tetra(p-tolyl)boron, trimethylammonium tetra(o-tolyl)boron, tributylammonium tetra(pentafluorophenyl)boron, tripropylammonium tetra(o,p-dimethylphenyl)boron, tributylammonium tetra(m,m- dimethylphenyl)boron, tributylammonium tetra(p-trifluoromethylphenyl)boron, tributylammonium tetra(pentafluorophenyl)boron, tri(n-butyl)ammonium tetra(o- tolyl)boron, N,N-dimethylanilinium tetra(phenyl)boron, N,N-diethylanilinium tetra(phenyl)boron, N,N-diethylanilinium tetra(phenyl)n-butylboron, N,N-2,4,6- pentamethylanilinium tetra(phenyl)boron, di-(isopropyl)ammonium tetra(pentafluorophenyl)boron, dicyclohexylammonium tetra(phenyl)boron, triphenylphosphonium tetra(phenyl)boron, tri(methylphenyl)phosphonium tetra(phenyl)boron, tri(dimethylphenyl)phosphonium tetra(phenyl)boron, tropylium tetrakispentafluorophenyl borate, triphenylmethylium tetrakispentafluorophenyl borate, benzene(diazonium)tetrakispentafluorophenyl borate, tropylium tetrakis(2, 3,5,6- tetrafluorophenyl)borate, triphenylmethylium tetrakis(2,3,5,6-tetrafluorophenyl)borate, benzene(diazonium) tetrakis(3,4,5-trifluorophenyl)borate, tropylium tetrakis(3,4,5- trifluorophenyl)borate, benzene(diazonium) tetrakis(3,4,5-trifluorophenyl)borate, tropylium tetrakis(l,2,2-trifluoroethenyl)borate, triphenylmethylium tetrakis(l ,2,2- trifluoroethenyl)borate, benzene (diazonium) tetrakis( l,2,2-trifluoroethenyl)borate, tropylium tetrakis(2,3,4,5-tetrafluorophenyl)borate, triphenyhnethylium tetrakis(2, 3,4,5- tetrafluorophenyl)borate, and benzene (diazonium) tetrakis(2,3,4,5 tetrafluorophenyl)borate. Readily available commercial ionic activators include N,N-dimethylanilinium tetrakispentafluorophenyl borate, and triphenylmethylium tetrakispentafluorophenyl borate.

[0114] Non-limiting example of hindered phenols include butylated phenolic antioxidants, butylated hydroxytoluene, 2,6-di-tertiarybutyl-4-ethyl phenol, 4,4'-methylenebis (2,6-di- tertiary-butylphenol), 1,3, 5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene and octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate.

[0115] To produce an active phosphinimine based catalyst system the quantity and mole ratios of the three or four components: the phosphinimine single site catalyst, the alkylaluminoxane, the ionic activator, and the optional hindered phenol may be optimized.

[0116] In an embodiment of the disclosure, the single site catalyst used to make the first polyethylene component produces no long chain branches, and the first polyethylene component will contain no measurable amounts of long chain branches.

[0117] LCB is a well-known structural phenomenon in ethylene copolymers and well known to those of ordinary skill in the art. Traditionally, there are three methods for LCB analysis, namely, nuclear magnetic resonance spectroscopy (NMR), for example see J.C. Randall, J Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, 29, 201; triple detection SEC equipped with a DRI, a viscometer and a low-angle laser light scattering detector, for example see W.W. Yau and D.R. Hill, Int. J. Polym. Anal. Charact. 1996; 2: 151; and rheology, for example see W.W. Graessley, Acc. Chem. Res. 1977, 10, 332-339. In embodiments of this disclosure, a long chain branch is macromolecular in nature, i.e. long enough to be seen in an NMR spectra, triple detector SEC experiments or rheological experiments.

[0118] In an embodiment of the disclosure, the first polyethylene component has from 0.5 to 100 short chain branches per thousand carbon atoms (SCB 1). In further embodiments, the first polyethylene component has from 0.5 to 50 short chain branches per thousand carbon atoms (SCB1), or from 0.5 to 25 short chain branches per thousand carbon atoms (SCB1), or from 0.5 to 15 short chain branches per thousand carbon atoms (SCB1), or from 0.5 to 10 short chain branches per thousand carbon atoms (SCB1), or from 0.5 to 5 short chain branches per thousand carbon atoms (SCB 1), or from 1 to 50 short chain branches per thousand carbon atoms, or from 1 to 25 short chain branches per thousand carbon atoms (SCB1), or from 1 to 15 short chain branches per thousand carbon atoms (SCB1), or from 1 to 10 short chain branches per thousand carbon atoms (SCB 1), or from 1 to 5 short chain branches per thousand carbon atoms (SCB1).

[0119] The short chain branching (i.e. the short chain branching per thousand backbone carbon atoms, SCB1) is the branching due to the presence of an a -olefin comonomer in the first polyethylene component and will for example have two carbon atoms for a 1 -butene comonomer, or four carbon atoms for a 1 -hexene comonomer, or six carbon atoms for a 1- octene comonomer, etc.

[0120] In an embodiment of the disclosure, the number of short chain branches per thousand carbon atoms in the first polyethylene component (SCB1), is greater than the number of short chain branches per thousand carbon atoms in the second polyethylene component (SCB2).

[0121] In an embodiment of the disclosure, the density, “dl” of the first polyethylene component is less than the density, “d2” of the second polyethylene component.

[0122] In an embodiment of the disclosure, the first polyethylene component has a density, “dl” of from 0.875 to 0.936 g / cm3, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the first polyethylene component has a density, dl of from 0.875 to 0.934 g / cm3, or from 0.875 to 0.932 g / cm3, or from 0.885 to 0.936 g / cm3, or from 0.885 to 0.934 g / cm3, or from 0.885 to 0.932 g / cm3, or from 0.875 to 0.930 g / cm3, or from 0.875 to 0.928 g / cm3, or from 0.885 to 0.930 g / cm3, or from 0.885 to 0.928 g / cm3, or from 0.895 to 0.936 g / cm3, or from 0.895 to 0.934 g / cm3, or from 0.895 to 0.932 g / cm3, or from 0.895 to 0.930 g / cm3, or from 0.905 to 0.936 g / cm3, or from 0.905 to 0.934 g / cm3, or from 0.905 to 0.932 g / cm3, or from 0.905 to 0.930 g / cm3.

[0123] In an embodiment of the disclosure, the melt index, h of the first polyethylene component is less than the melt index, h of second polyethylene component.

[0124] In embodiments of the disclosure the first polyethylene component has a melt index, I2 of, < 10 g / lOmin, or < 5.0 g / lOmin, or < 2.5 g / lOmin, or < 1.0 g / lOmin, or < 1.0 g / lOmin. In another embodiment of the disclosure, the first polyethylene component has a melt index, I2 of from 0.001 to 10.0 g / lOmin, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the melt index, I2 of the first polyethylene component may be from 0.001 to 7.5 g / lOmin, or from 0.001 to 5.0 g / lOmin, or from 0.001 to 2.5 g / lOmin, or 0.001 to 1.0 g / lOmin, or from 0.01 to 10.0 g / lOmin, or from 0.01 to 7.5 g / lOmin, or from 0.01 to 5.0 g / lOmin, or from 0.01 to 2.5 g / lOmin, or from 0.01 to 1.0 g / lOmin, or from 0.1 to 10.0 g / lOmin, or from 0.1 to 7.5 g / lOmin, or from 0.1 to 5.0 g / lOmin, or from 0.1 to 2.5 g / lOmin, or from 0.1 to 1.0 g / lOmin, or from 0.1 to less than 1.0 g / lOmin.

[0125] In an embodiment of the disclosure, the first polyethylene component has a weight average molecular weight, Mw* of at least 100,000 g / mol. In further embodiments of the disclosure, the first polyethylene component has a weight average molecular weight, Mw* of from 75,000 to 300,000 g / mol, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the first polyethylene component has a weight average molecular weight, Mw1of from 100,000 to 250,000 g / mol, or from 100,000 to 225,000 g / mol, or from 100,000 to 200,000 g / mol, or from 125,000 to 200,000 g / mol, or from 125,000 to 180,000 g / mol.

[0126] In an embodiment of the disclosure, the first polyethylene component has a melt flow ratio, I21 / I2 of less than 25, or less than 23, or less than 20.

[0127] In embodiments of the disclosure, the upper limit on the molecular weight distribution, Mw / Mnof the first polyethylene component may be about 2.7, or about 2.5, or about 2.4, or about 2.3, or about 2.2. In embodiments of the disclosure, the lower limit on the molecular weight distribution, Mw / Mnof the first polyethylene component may be about 1.6, or about 1.7, or about 1.8, or about 1.9.

[0128] In embodiments of the disclosure, the first polyethylene component has a molecular weight distribution, Mw / Mn of < 3.0, or < 3.0, or < 2.7, or < 2.7, or < 2.5, or < 2.5, or < 2.3, or < 2.3, or < 2.1, or < 2. 1, or about 2. In another embodiment of the disclosure, the first polyethylene component has a molecular weight distribution, Mw / Mnof from 1.7 to 3.0, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the first polyethylene component has a molecular weight distribution, Mw / Mn of from 1.7 to 2.7, or from 1.8 to 2.7, or from 1.8 to 2.5, or from 1.8 to 2.3, or from 1.9 to 2.1.

[0129] In embodiments of the disclosure, the upper limit on the CDBI50 of the first polyethylene component may be about 98 weight%, in other cases about 95 wt% and in still other cases about 90 wt%. In embodiments of the disclosure, the lower limit on the CDBI50 of the first polyethylene component may be about 70 weight%, in other cases about 75 wt% and in still other cases about 80 wt%.

[0130] In an embodiment of the disclosure, a single site catalyst which gives an ethylene copolymer having a CDBI50 of at least 65% by weight, or at least 70%, or at least 75%, or at least 80%, or at least 85%, during solution phase polymerization in a single reactor, is used in the preparation of the first polyethylene component.

[0131] In embodiments of the present disclosure, the first polyethylene component is ethylene copolymer which has a CDBI50 of greater than about 60% by weight, or greater than about 65%, or greater than about 70%, or greater than about 75%, or greater than about 80%, or greater than about 85%. In embodiments of the disclosure, the weight percent (wt%) of the first polyethylene component in the polyethylene composition (i.e. the weight percent of the first polyethylene component based on the total weight of the first polyethylene component and the second polyethylene component) may be from about 5 wt% to about 75 wt%, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the weight percent (wt%) of the first polyethylene component in the polyethylene composition may be from about 5 wt% to about 65 wt%, or from about 10 wt% to about 60 wt%, or from about 10 wt% to about 50 wt%, or from about 10 wt% to about 45 wt%, or from about 10 wt% to about 40 wt% or from about 15 wt% to about 50 wt%, or from about 20 wt% to about 50 wt%, or from about 15 wt% to about 40 wt%, or from about 20 wt% to about 40 wt%, or from about 20 wt% to about 35 wt%.

[0132] The Second Polyethylene Component

[0133] In an embodiment of the disclosure the second polyethylene component comprises only ethylene and is an ethylene homopolymer.

[0134] In an embodiment of the disclosure the second polyethylene component is an ethylene copolymer and comprises both polymerized ethylene and at least one polymerized a-olefin comonomer, with polymerized ethylene being the majority species.

[0135] In embodiments of the disclosure, a-olefins which may be copolymerized with ethylene to make the second polyethylene component may be selected from the group comprising 1 -propene, 1 -butene, 1 -pentene, 1 -hexene and 1 -octene and mixtures thereof.

[0136] In an embodiment of the disclosure, the second polyethylene component is made with a single site catalyst, non-limiting examples of which include phosphinimine catalysts, metallocene catalysts, and constrained geometry catalysts, all of which are well known in the art.

[0137] In an embodiment of the disclosure the second polyethylene component is made using a single site polymerization catalyst in a solution phase polymerization process.

[0138] In an embodiment of the disclosure, the second polyethylene component is an ethylene / 1 -octene copolymer.

[0139] In an embodiment of the disclosure, the second polyethylene component is made with a phosphinimine catalyst.

[0140] In an embodiment of the disclosure, the second polyethylene component is made with a phosphinimine catalyst having the formula I: (LA)aM(PI)b(Q)n (I) wherein (LA) represents is cyclopentadienyl-type ligand; M represents a metal atom selected from the group consisting of Ti, Zr, and Hf; PI represents a phosphinimine ligand; Q represents an activatable ligand as already defined above; a is 0 or 1; b is 1 or 2; (a+b) = 2; n is 1 or 2, and; the sum of (a+b+n) equals the valance of the metal M.

[0141] As used herein, the term “cyclopentadienyl-type” ligand is meant to include ligands which contain at least one five-carbon ring which is bonded to the metal via eta-5 (or in some cases eta-3) bonding. Thus, the term “cyclopentadienyl-type” includes, for example, unsubstituted cyclopentadienyl, singly or multiply substituted cyclopentadienyl, unsubstituted indenyl, singly or multiply substituted indenyl, unsubstituted fluorenyl and singly or multiply substituted fluorenyl. Hydrogenated versions of indenyl and fluorenyl ligands are also contemplated for use in the current disclosure, so long as the five-carbon ring which bonds to the metal via eta-5 (or in some cases eta-3) bonding remains intact. Substituents for a cyclopentadienyl ligand, an indenyl ligand (or hydrogenated version thereof) and a fluorenyl ligand (or hydrogenated version thereof) may be selected from the group consisting of a C1-30 hydrocarbyl radical (which hydrocarbyl radical may be unsubstituted or further substituted by for example a halide and / or a hydrocarbyl group; for example a suitable substituted C1-30 hydrocarbyl radical is a pentafluorobenzyl group such as -CH2C6F5); a halogen atom; a C1-8 alkoxy radical; a Ce-io aryl or aryloxy radical (each of which may be further substituted by for example a halide and / or a hydrocarbyl group); an amido radical which is unsubstituted or substituted by up to two C1-8 alkyl radicals; a phosphide radical which is unsubstituted or substituted by up to two C1-8 alkyl radicals; a silyl radical of the formula -Si(R')3 wherein each R' is independently selected from the group consisting of hydrogen, a C1-8 alkyl or alkoxy radical, Ce-io aryl or aryloxy radicals; and a germanyl radical of the formula -Ge(R')3 wherein R' is as defined directly above.

[0142] The phosphinimine ligand, PI, is defined by formula:

[0143] (Rp)3P = N - wherein the Rpgroups are independently selected from: a hydrogen atom; a halogen atom; C1-20 hydrocarbyl radicals which are unsubstituted or substituted with one or more halogen atom(s); a C1-8 alkoxy radical; a Ce-io aryl radical; a Ce-io aryloxy radical; an amido radical; a silyl radical of formula -Si(Rs)3, wherein the Rsgroups are independently selected from, a hydrogen atom, a C1-8 alkyl or alkoxy radical, a Ce-io aryl radical, a Ce-io aryloxy radical, or a germanyl radical of formula -Ge(RG)3, wherein the RGgroups are defined as Rsis defined in this paragraph.

[0144] In an embodiment of the disclosure, the metal, M in the phosphinimine catalyst is titanium, Ti.

[0145] In an embodiment of the disclosure, the single site catalyst used to make the second ethylene copolymer is cyclopentadienyl tri(tertiarybutyl)phosphinimine titanium dichloride, Cp((t-Bu)3PN)TiC12.

[0146] As already discussed above, in addition to the single site catalyst molecule per se, an active single site catalyst system may further comprise one or more of the following: an alkylaluminoxane co-catalyst and an ionic activator, both of which have already been defined above. The single site catalyst system may also optionally comprise a hindered phenol, as already defined.

[0147] To produce an active phosphinimine based catalyst system the quantity and mole ratios of the three or four components: the phosphinimine single site catalyst, the alkylaluminoxane, the ionic activator, and the optional hindered phenol may be optimized.

[0148] In an embodiment of the disclosure, the single site catalyst used to make the second polyethylene component produces no long chain branches, and the second polyethylene component will contain no measurable amounts of long chain branches.

[0149] The second ethylene copolymer may contain catalyst residues that reflect the chemical.

[0150] In an embodiment of the disclosure, the short chain branching in the second polyethylene component can be from about 0.01 to about 10.0 short chain branches per thousand carbon atoms (SCB2 / 1000Cs). In further embodiments of the disclosure, the short chain branching in the second ethylene copolymer can be from 0.01 to 7.5, or from 0.01 to 5.0, or from 0.01 to 3.0, or from 0.01 to 1.5, or from 0.01 to 1.0, or from 0.01 to 0.5, or from 0.01 to 0.1, or about 0 branches per thousand carbon atoms (SCB2 / 1000Cs).

[0151] The short chain branching (i.e. the short chain branching per thousand backbone carbon atoms, SCB2) is the branching due to the presence of an a-olefin comonomer in the second polyethylene component and will for example have two carbon atoms for a 1 -butene comonomer, or four carbon atoms for a 1 -hexene comonomer, or six carbon atoms for a 1- octene comonomer, etc.

[0152] In an embodiment of the disclosure, the number of short chain branches per thousand carbon atoms in the second polyethylene component (SCB2), is fewer than the number of short chain branches per thousand carbon atoms in the first polyethylene component (SCB1).

[0153] In an embodiment of the disclosure, the density, “d2” of the second polyethylene component is greater than the density, “dl” of the first polyethylene component.

[0154] In an embodiment of the disclosure, the second polyethylene component has a density, “d2” of from 0.936 to 0.975 g / cm3, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the second polyethylene component has a density, d2 of from 0.936 to 0.970 g / cm3, or from 0.938 to 0.970 g / cm3, or from 0.940 to 0.970 g / cm3, or from 0.942 to 0.970 g / cm3, or from 0.942 to 0.970 g / cm3, or from 0.936 to 0.965 g / cm3, or from 0.938 to 0.965 g / cm3, or from 0.940 to 0.965g / cm3, or from 0.942 to 0.965 g / cm3, or from 0.936 to 0.962 g / cm3, or from 0.938 to 0.962 g / cm3, or from 0.940 to 0.962 g / cm3, or from 0.942 to 0.962 g / cm3, or from 0.940 to 0.960 g / cm3, or from 0.940 to 0.955 g / cm3, or from 0.940 to 0.950 g / cm3.

[0155] In an embodiment of the disclosure, the melt index, h of the second polyethylene component is greater than the melt index, h of first polyethylene component.

[0156] In an embodiment of the disclosure the second polyethylene component has a melt index, h of> 1.0 g / lOmin.

[0157] In an embodiment of the disclosure the second polyethylene component has a melt index, h of > 5.0 g / lOmin.

[0158] In an embodiment of the disclosure the second polyethylene component has a melt index, h of > 10.0 g / lOmin.

[0159] In embodiments of the disclosure the second polyethylene component has a melt index, h of from 1 to 1,000 including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the melt index, h of the second polyethylene component is from 1 to 500 g / lOmin, or from 1 to 250 g / lOmin, or from 5 to 500 g / lOmin, or from 1 to 100 g / lOmin, or from 5 to 100 g / lOmin, or from 1 to 50 g / lOmin, or from 5 to 50 g / lOmin, or from 1 to 25 g / lOmin, or from 5 to 25 g / lOmin.

[0160] In an embodiment of the disclosure, the second polyethylene component has a weight average molecular weight, Mw2of < 100,000 g / mol. In another embodiment the second polyethylene component has a weight average molecular weight, Mw2of less than 90,000 g / mol. In still further embodiments the second polyethylene component has a weight average molecular weight, Mw2of from 5,000 to 100,000 g / mol, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the second polyethylene component has a weight average molecular weight, Mw2of from 50,000 to 95,000 g / mol, or from 60,000 to 95,000 g / mol, or from 50,000 to 85,000 g / mol, or from 60,000 to 85,000 g / mol, or from 65,000 to 85,000 g / mol, or from 25,000 to 95,000 g / mol, or from 35,000 to 95,000 g / mol, or from 40,000 to 85,000 g / mol, or from 40,000 to 80,000 g / mol, or from 35,000 to 75,000 g / mol.

[0161] In an embodiment of the disclosure, the second polyethylene component has a melt flow ratio, I21 / I2 of less than 25, or less than 23, or less than 20.

[0162] In embodiments of the disclosure, the upper limit on the molecular weight distribution, Mw / Mnof the second polyethylene component may be about 2.7, or about 2.5, or about 2.4, or about 2.3, or about 2.2. In embodiments of the disclosure, the lower limit on the molecular weight distribution, Mw / Mnof the second polyethylene component may be about 1.6, or about 1.7, or about 1.8, or about 1.9.

[0163] In embodiments of the disclosure, the second polyethylene component has a molecular weight distribution, Mw / Mnof < 3.0, or < 3.0, or < 2.7, or < 2.7, or < 2.5, or < 2.5, or < 2.3, or < 2.3, or < 2.1, or < 2.1, or about 2. In another embodiment of the disclosure, the second polyethylene component has a molecular weight distribution, Mw / Mnof from 1.7 to 3.0, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the second polyethylene component has a molecular weight distribution, Mw / Mn of from 1.8 to 2.7, or from 1.8 to 2.5, or from 1.8 to 2.3, or from 1.7 to 2.3, or from 1.9 to 2.1.

[0164] In embodiments of the disclosure, the upper limit on the CDBI50 of the second polyethylene component may be about 98 weight%, in other cases about 95 wt% and in still other cases about 90 wt%. In embodiments of the disclosure, the lower limit on the CDBI50 of the second polyethylene component may be about 70 weight%, in other cases about 75 wt% and in still other cases about 80 wt%.

[0165] In an embodiment of the disclosure, a single site catalyst which gives an ethylene copolymer having a CDBI50 of at least 65% by weight, or at least 70%, or at least 75%, or at least 80%, or at least 85%, during solution phase polymerization in a single reactor, is used in the preparation of the second polyethylene component.

[0166] In an embodiment of the present disclosure, the second polyethylene component is ethylene copolymer which has a CDBI50 of greater than about 60% by weight, or greater than about 65%, or greater than about 70%, or greater than about 75%, or greater than about 80%, or greater than about 85%.

[0167] In embodiments of the disclosure, the weight percent (wt%) of the second polyethylene component in the polyethylene composition (i.e. the weight percent of the second polyethylene component based on the total weight of the first polyethylene component and the second polyethylene component) may be from about 95 wt% to about 25 wt%, including any narrower ranges within this range and any values encompassed by these ranges. For example, in embodiments of the disclosure, the weight percent (wt%) of the second polyethylene component in the polyethylene copolymer composition may be from about 95 wt% to about 35 wt%, or from about 90 wt% to about 40 wt%, or from about 90 wt% to about 50 wt%, or from about 90 wt% to about 55 wt%, or from about 90 wt% to about 60 wt%, or from about 85 wt% to about 50 wt%, or from about 80 wt% to about 50 wt%, or from about 85 wt% to about 60 wt%, or from about 80 to 60 wt%, or from about 80 to 65 wt%.

[0168] Additional Additives and Adjuvants

[0169] The thermoplastic compositions and the manufactured rotomolded articles described herein may optionally include, and depending on the intended end-use, further additives and adjuvants. To be clear, the further additives and adjuvants described in this section refer to those additives and adjuvants not already referred to herein as a “benzo-furanone antioxidant compound” and which are already defined above.

[0170] Further additives can be added to the polyethylene composition during an extrusion or compounding step, but other suitable known methods will be apparent to a person skilled in the art. The further additives can be added as is or as part of a separate polymer component added during an extrusion or compounding step. For example, the further additives may be added to the polyethylene composition by way of a “masterbatch”, where the term “masterbatch” refers to the practice of first melt mixing the additive with a small amount of the polyethylene composition, followed by melt mixing the "masterbatch" with the remaining bulk of the polyethylene composition.

[0171] Non-limiting examples of further additives and adjuvants which may be combined with the polyethylene composition or included in a manufactured rotomolded article include anti-blocking agents, antioxidants, heat stabilizers, nitrones, antacids, metal deactivators, slip agents, processing aids, anti-static additives, colorants, dyes, pigments, filler materials, metal oxides (e.g. zinc oxide), Ultra-Violet (UV) light stabilizers, heat stabilizers, UV light absorbers, lubricants, pigments, plasticizers, reinforcing agents, nano-scale organic or inorganic materials, antistatic agents, metal stearates, release agents such as zinc stearates, nucleating agents, and combinations thereof.

[0172] The further additives that can be optionally added are typically added in amount of up to 20 weight percent (wt.%), for example, from about 0. 1 wt.% up to about 20 wt.%, based on the weight of the polyethylene composition.

[0173] One or more nucleating agent(s) may be introduced into the polyethylene composition by kneading a mixture of the polymer, usually in powder or pellet form, with the nucleating agent, which may be utilized alone or in the form of a concentrate containing further additives such as stabilizers, pigments, antistatics, UV stabilizers and fillers. It should be a material which is wetted or absorbed by the polymer, which is insoluble in the polymer and of melting point higher than that of the polymer, and it should be homogeneously dispersible in the polymer melt in as fine a form as possible (1 to 10 pm). Compounds known to have a nucleating capacity for polyolefins, such as the polyethylene composition described herein, include salts of aliphatic monobasic or dibasic acids or arylalkyl acids, such as sodium succinate or aluminum phenylacetate; and alkali metal or aluminum salts of aromatic or alicyclic carboxylic acids such as sodium P-naphthoate. Another compound known to have nucleating capacity is sodium benzoate. The effectiveness of nucleation may be monitored microscopically by observation of the degree of reduction in size of the spherulites into which the crystallites are aggregated.

[0174] A more detailed list of some further additives which may be added to the polyethylene composition of the present disclosure and which may be used in rotomolded articles follows:

[0175] Phosphite or Phosphonite Antioxidant Compounds

[0176] Phosphite antioxidant compounds which may be used in embodiments of the disclosure include aryl phosphites, such as an aryl monophosphite. The term aryl monophosphite refers to a phosphite stabilizer which contains: (1) only one phosphorus atom per molecule; and (2) at least one aryloxide (which may also be referred to as phenoxide) group which is bonded to the phosphorus.

[0177] In an embodiment of the disclosure, aryl monophosphites contain three aryloxide radicals - for example, tris phenyl phosphite is the simplest member of this preferred group of aryl monophosphites.

[0178] In another embodiment of the disclosure, aryl monophosphites contain Ci to Cio alkyl substituents on at least one of the aryloxide groups. These substituents may be linear (as in the case of nonyl substituents) or branched (such as isopropyl or tertiary butyl substituents).

[0179] Non-limiting examples of aryl monophosphites which may be used as a phosphite antioxidant compound in embodiments of the disclosure, include those selected from the group consisting of triphenyl phosphite; diphenyl alkyl phosphites; phenyl dialkyl phosphites; tris(nonylphenyl) phosphite [WESTON® 399, available from SI Group]; tris(2,4-di-tert-butylphenyl) phosphite [IRGAFOS® 168; CAS Reg. No. 31570-04-4, available from BASF Corporation] ; bis(2,4-di-tert-butyl-6-methylphenyl) ethyl phosphite [IRGAFOS 38, available from BASF Corporation.]; 2,2',2"-nitrilo[triethyltris(3,3'5,5'-tetra- tert-butyl-I,r-biphenyl-2,2'-diyl) phosphite [IRGAFOS 12, available from BASF Corporation]; WESTON 705 [CAS Reg. No. 939402-02-5] available from SI Group; as well as mixtures thereof.

[0180] In embodiments of the disclosure, the amount of aryl monophosphite added to the polyethylene composition is added in from 200 to 2,000 ppm (based on the weight of the polyethylene composition), or from 300 to 1,500 ppm, or from 400 to 1,000 ppm.

[0181] In some embodiments, phosphorus containing antioxidant compounds, may be selected from diphosphite compounds.

[0182] In some embodiments, phosphorus containing antioxidant compounds, may be selected from phosphonite and diphosphonite compounds.

[0183] As used herein, the term diphosphite refers to a phosphite compound or phosphite stabilizer which contains at least two phosphorus atoms per phosphite molecule (and, similarly, the term diphosphonite refers to a phosphonite compound or phosphonite stabilizer which contains at least two phosphorus atoms per phosphonite molecule).

[0184] In some embodiments of the disclosure, a polyphosphite material may be used as a phosphite antioxidant compound.

[0185] Non-limiting examples of diphosphites, polyphosphites and diphosphonites which may be used in embodiments of the disclosure include those selected from the group consisting of distearyl pentaerythritol diphosphite; diisodecyl pentaerythritol diphosphite, bis(2,4 di-tert-butylphenyl) pentaerythritol diphosphite [ULTRANOX® 626, available from SI Group]; bis(2,6-di-tert-butyl-4-methylpenyl) pentaerythritol diphosphite; bisisodecyloxy- pentaerythritol diphosphite; bis(2,4-di-tert-butyl-6-methylphenyl) pentaerythritol diphosphite; bis(2,4,6-tri-tert-butylphenyl) pentaerythritol diphosphite; tetrakis(2,4-di-tert- butylphenyl)4,4'-bipheylene-diphosphonite [IRGAFOS P-EPQ®, available from BASF Corporation]; bis(2,4-dicumylphenyl)pentaerythritol diphosphite [DOVERPHOS® S-9228 (CAS No 154862-43-8), or DOVERPHOS S-9228-T, or DOVERPHOS S-9228-PC];

[0186] DOVERPHOS 11 [CAS Reg. No. 1227937-46-3]; DOVERPHOS 12; DOVERPHOS LGP- 11; DOVERPHOS LGP-12; DOVERPHOS LGP-12LV; as well as mixtures thereof.

[0187] In an embodiment a phosphite antioxidant compound has the formula IV : wherein R11, R22, R44and R55are independently selected from the group consisting of a hydrogen atom and a C1-C12 alkyl group; R33is selected from the group consisting of a hydrogen atom and a Ci-Cs alkyl group; L represents a single bond or is an alkylene group having the formula -CHR66-, wherein R66is a hydrogen atom or a C1-C12 alkyl group; A is an alkylene group having the formula -CHR77-, a carbonyl group having the formula - C*(=O)CHR77- where C* is bonded to O in formula I, or a carbonyl group having the formula -(C=O)-, wherein R77is a hydrogen atom or a C1-C12 alkyl group; and wherein one of Y and Z is selected from the group consisting of a hydroxyl group, an alkoxy group, an aryloxy group, an alkylaryloxy group and an arylalkyloxy group, while the other one of Y and Z is selected from the group consisting of a hydrogen atom and a C1-C12 alkyl group.

[0188] In an embodiment, a phosphite antioxidant compound is 6-[3-(3-tert-Butyl-4- hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-tert- butyldibenzo[d,f][ 1,3, 2] dioxaphosphepin (CAS NO. 203255-81-6). This compound is sold under the trademark name SUMILZER® GP by Sumitomo. The use of this phosphite is described in combination with a polyol (such as pentaerythritol) in U.S. Pat. No. 7,820,746. A polyol may also be (optionally) used in this disclosure but it is not essential.

[0189] In embodiments of the disclosure, a phosphite, and / or a diphosphite, and / or a phosphonite, and / or a diphosphonite and / or polyphosphite is added to the polyethylene composition in from 200 to 5,000 ppm, or from 200 to 4,000 ppm, or from 200 ppm to 2,000 ppm, of from 100 ppm to 2,000 ppm, or from 300 to 1,500 ppm, or from 400 to 1,000 ppm (based on the weight of the polyethylene composition). Hindered Phenolic Antioxidant Compounds

[0190] In embodiments, a hindered phenolic antioxidant may be an alkylated mono-phenol compound. Suitable non-limiting examples which may be used in embodiments of the disclosure include those selected from the group consisting of 2,6-di-tert-butyl-4- methylphenol; 2-tert-butyl-4,6-dimethylphenol; 2,6-di-tert-butyl-4-ethylphenol; 2,6-di-tert- butyl-4-n-butylphenol; 2,6-di-tert-butyl-4isobutylphenol; 2,6-dicyclopentyl-4- methylphenol; 2-(.alpha.-methylcyclohexyl)-4,6 dimethylphenol; 2,6-di-octadecyl-4- methylphenol; 2,4,6,-tricyclohexyphenol; and 2,6-di-tert-butyl-4-methoxymethylphenol; as well as mixtures thereof.

[0191] Two (non-limiting) examples of a hindered phenolic antioxidant which can be used in embodiments of the disclosure, are sold under the trademarks IRGANOX® 1010 (CAS Registry number 6683-19-8) and IRGANOX 1076 (CAS Registry number 2082-79-3) by BASF Corporation.

[0192] In embodiments a hindered phenolic antioxidant compound is selected from the group consisting of d,l-alpha-tocopherol, d,l-beta-tocopherol, d,l-gamma-tocopherol, d,l- delta-tocopherol, n-propyl gallate (propyl, 3,4,5- trihydroxybenzoate) and mixtures thereof.

[0193] In an embodiment, a hindered phenolic antioxidant comprises d,l-alpha tocopherol, which is 3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-l-benzopyran-6-ol (CAS NO. 10191-41-0). This compound is sold under the trademark name IRGANOX E201 by BASF. A commercially available variant, which is also contemplated for use in the present disclosure, and which additionally includes d,l-beta-tocopherol, d,l-gamma- tocopherol, and d,l-delta-tocopherol, is sold under the tradename COVI-OX® T90 by BASF. Hence, in an embodiment, the first hindered phenolic antioxidant comprises d,l-alpha- tocopherol, d,l-beta-tocopherol, d,l-gamma-tocopherol, d,l-delta-tocopherol, and mixtures thereof.

[0194] In an embodiment of the disclosure, the amount of a hindered phenolic antioxidant added to the polyethylene composition is from 200 to 5,000 ppm, or from 200 to 4,000 ppm, or from 200 ppm to 2,000 ppm, of from 100 ppm to 2,000 ppm, or from 300 to 1,500 ppm, or from 400 to 1,000 ppm (based on the weight of the polyethylene composition).

[0195] Hindered Amine Light Stabilizers

[0196] Plastic parts which are intended for long term use, can in embodiments of the present disclosure, contain at least one Hindered Amine Light Stabilizer (HALS). HALS are well known to those skilled in the art. When employed, the HALS may in an embodiment of the disclosure be a commercially available material and may be used in a conventional manner and in a conventional amount.

[0197] Commercially available HALS which may be used in embodiments of the disclosure include those sold under the trademarks CHIMASSORB® 119; CHIMASSORB 944; CHIMASSORB 2020; TINUVIN® 622 and TINUVIN 770 from BASF, and CYASORB® UV 3346, CYASORB UV 3529, CYASORB UV 4801, and CYASORB UV 4802 from Solvay. In some embodiments of the disclosure, the use of mixtures of more than one HALS is contemplated.

[0198] In embodiments of the disclosure, suitable HALS include those selected from the group consisting of bis(2,2,6,6-tetramethylpiperidyl)-sebacate; bis-5(l,2,2,6,6- pentamethylpiperidyl)-sebacate; n-butyl-3, 5 -di -tert-butyl -4-hydroxybenzyl malonic acid bis(I,2,2,6,6,-pentamethylpiperidyl)ester; condensation product of l-hydroxyethyl-2, 2,6,6- tetramethyl-4-hydroxy-piperidine and succinic acid; condensation product of N,N'-(2, 2,6,6- tetramethylpiperidyl)-hexamethylendiamine and 4-tert-octylamino-2,6-dichloro- 1,3,5 -s- triazine; tris-(2,2,6,6-tetramethylpiperidyl)-nitrilotriacetate, tetrakis-(2,2,6,6-tetramethyl-4- piperidyl)-I,2,3,4butane-tetra-arbonic acid; and l,l'(l,2-ethanediyl)-bis-(3, 3,5,5- tetramethylpiperazinone); and mixtures thereof.

[0199] In an embodiment of the disclosure, the amount of a hindered amine light stabilizer added to the polyethylene composition is added in from 100 to 2,000 ppm, or from 400 to 1,000 ppm (based on the weight of the polyethylene composition).

[0200] Hydroxylamines

[0201] It is known to use hydroxylamines and derivatives thereof (including amine oxides) as additives for polyethylene compositions used to prepare rotomolded parts, as disclosed in for example U.S. Pat. No. 6,444,733 and in embodiments of the present disclosure, the hydroxylamines and derivatives disclosed in this patent may also be suitable for use.

[0202] In embodiments, a hydroxylamine may be selected from the group consisting of N,N-dibenzylhydroxylamine; N,N-diethylhydroxylamine; N,N-dioctylhydroxylamine; N,N- dilaurylhydroxylamine ; N,N -ditetradecylhydroxylamine ; N,N -dihexadecylhydroxylamine ; N,N -dioctadecylhydroxylamine ; N -hexadecyl -N -octadecylhydroxylamine ; N -heptadecyl -N - octadecylhydroxylamine; and N,N-dialkylhydroxylamine derived from hydrogenated tallow amine; and mixtures thereof. The analogous amine oxides to may also be suitable for use in some embodiments. In an embodiment of the disclosure, a useful hydroxylamine for inclusion in the polyethylene composition can be selected from N,N-dialkylhydroxylamines, a commercially available example of which is the N,N-di(alkyl) hydroxylamine sold as IRGASTAB® FS 042 (CAS No 143925-92-2) commercially available from by BASF and which is reported to be prepared by the direct oxidation of N,N - di(hydrogenated) tallow amine.

[0203] In embodiments of the disclosure, the amount of hydroxylamine added to the polyethylene composition is from 100 to 2,000 ppm, or from 400 to 1,000 ppm (based on the weight of the polyethylene composition). In embodiments of the disclosure, the amount of hydroxylamine added to the polyethylene composition is at least about 400 ppm, or at least about 500 ppm, or at least about 600 ppm, or at least about 700 ppm, or at least about 750 ppm, or at least about 800 ppm from 400 to 1,000 ppm (based on the weight of the polyethylene composition).

[0204] In an embodiment of the disclosure, a thermoplastic composition for use in a rotomolding process comprises a polyethylene composition and an additive package comprising: a benzo-furanone antioxidant compound having the formula I: wherein n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; and R3 is independently a Ci-Cs alkyl group or a OH group.

[0205] In an embodiment of the disclosure, a thermoplastic composition for use in a rotomolding process comprises a polyethylene composition and an additive package comprising: a benzo-furanone antioxidant compound having the formula I: wherein n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; and R3 is independently a Ci-Cs alkyl group or a OH group; and one or more of: a hindered phenolic antioxidant compound; a phosphite antioxidant compound; a phosphonite antioxidant compound; a metal oxide compound; a hindered amine light stabilizer; and a hydroxylamine compound. In an embodiment of the disclosure, a thermoplastic composition for use in a rotomolding process comprises a polyethylene composition and an additive package comprising: a benzo-furanone antioxidant compound having the formula I: wherein n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; and R3 is independently a Ci-Cs alkyl group or a OH group; a hindered phenolic antioxidant compound; a phosphite or phosphonite antioxidant compound; a metal oxide compound; a hindered amine light stabilizer; and a hydroxylamine compound.

[0206] In an embodiment of the disclosure, a rotomolding process for making a rotomolded article comprises: preparing a thermoplastic composition by combining a polyethylene composition with an additive package; adding the thermoplastic composition to a mold; heating the mold; rotating the mold about at least 2 axes of rotation; cooling the mold; and removing the rotomolded article from the mold; wherein the additive package comprises a benzo-furanone antioxidant compound having the formula I: wherein n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; and R3 is independently a Ci-Cs alkyl group or a OH group.

[0207] In an embodiment of the disclosure, a rotomolding process for making a rotomolded article comprises: preparing a thermoplastic composition by combining a polyethylene composition with an additive package; adding the thermoplastic composition to a mold; heating the mold; rotating the mold about at least 2 axes of rotation; cooling the mold; and removing the rotomolded article from the mold; wherein the additive package comprises: a benzo-furanone antioxidant compound having the formula I: wherein n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; and R3 is independently a Ci-Cs alkyl group or a OH group; and one or more of: a hindered phenolic antioxidant compound; a phosphite antioxidant compound; a phosphonite antioxidant compound; a metal oxide compound; a hindered amine light stabilizer; and a hydroxylamine compound.

[0208] In an embodiment of the disclosure, a rotomolding process for making a rotomolded article comprises: preparing a thermoplastic composition by combining a polyethylene composition with an additive package; adding the thermoplastic composition to a mold; heating the mold; rotating the mold about at least 2 axes of rotation; cooling the mold; and removing the rotomolded article from the mold; wherein the additive package comprises: a benzo-furanone antioxidant compound having the formula I: wherein n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; and R3 is independently a Ci-Cs alkyl group or a OH group; a hindered phenolic antioxidant compound; a phosphite or phosphonite antioxidant compound; a metal oxide compound; a hindered amine light stabilizer; and a hydroxylamine compound.

[0209] Rotomolded Articles

[0210] Rotational molding is a process well-known to the person skilled in the art Typically, for use in a rotational molding process, a polyethylene composition can be manufactured in powder or pellet form. The rotational molding process may additionally comprise process steps for manufacturing the polyethylene composition. For rotational molding, powders are often used and may have a particle size smaller than or equal to 35 US mesh. The grinding may be done cryogenically, if necessary. Thereafter, a polymer powder is placed inside a hollow mold and then heated within the mold as the mold is rotated. A mold is usually rotated biaxially, i.e., rotated about two perpendicular axes simultaneously. A mold is typically heated externally (generally with a forced air circulating oven). Generally, rotomolding process steps include: tumbling, heating and melting of a polymer powder, followed by coalescence, fusion or sintering and cooling to remove the molded article. In an embodiment, a rotomolding process will comprise the steps of: a) loading of the mold; b) rotation of the mold; c) heating of the mold; d) cooling; and e) release from the mold. Steps b) and c) are typically carried out simultaneously. Steps b) and d) may also be carried out simultaneously.

[0211] The quantity of powder and / or of micropellets introduced into the mold depends on the size of the article and on the desired wall thickness. In some embodiments, the wall thickness of the article is of at least 2 mm to at most 25 mm when the article comprises one or more layers, or at least 500 pm to at most 25 mm when the comprises a monolayer (single layer).

[0212] The thermoplastic composition of the present disclosure may in certain embodiments of the disclosure, be processed in commercial rotational molding machines. The time and temperatures used will depend upon factors including the thickness of the part being rotomolded, and one skilled in the art can readily determine suitable processing conditions. By way of providing some non-limiting examples, the oven temperature range during the heating step may be from 400°F to 800°F, or from about 500°F to about 700°F, or from about 575 °F to about 650°F.

[0213] After the heating step the mold is cooled. The part must be cooled enough to be easily removed from the mold and to retain its shape. The mold may be removed from the oven while continuing to rotate. Cool air is first blown on the mold. The air may be at ambient temperature. After the air has started to cool the mold for a controlled time period, a water spray may be used. The water used may be at cold tap water temperature, for example it may be from about 4°C (40°F) to about 16°C (60°F). After the water cooling step, another air cooling step may be used. This may be a short step during which the equipment dries with heat removal during the evaporation of the water.

[0214] The heating and cooling cycle times will depend on the equipment used and the article being molded. Specific factors include the part thickness in the mold material. By way of providing a non-limiting example, conditions for an * / s inch thick part in a steel mold may be, to heat the mold in the oven with air at about 316°C (600°F) for about 15 minutes; the part may then be cooled in ambient temperature forced air for about 8 minutes and then a tap water spray at about 10°C (50°F) for about 5 minutes; optionally, the part may be cooled in ambient temperature forced air for an additional 2 minutes.

[0215] During the heating and cooling steps the mold containing the molded article is preferably continually rotated. Typically this is done along two perpendicular axes. The rate of rotation of the mold about each axis is limited by machine capability and the shape of the article being molded. A typical, non-limiting range of operations which may be used with the present disclosure is to have the ratio of rotation of the major axis to the minor axis of about 1:8 to 10: 1 or from about 1:2 to 8: 1.

[0216] The duration of the molding varies according to dimensions and the thickness of rotomolded article; it may, for example, range can range from 5 minutes to 600 minutes. The duration and the time of cooling step depends on the installation, on the dimensions of the article to be molded and of the type of article which one wishes to obtain.

[0217] The walls of the rotomolded articles can comprise one or more successive layers, at least one of which comprises the thermoplastic composition described herein. It is thus possible to manufacture articles with walls comprising for example two or more layers. There are several known methods to manufacture multilayered rotomolded articles: by manual introduction of material during the rotomolding cycle, or by the use of a drop-box, or by a one-shot system wherein each layer has a different melting temperature and are introduced into the mold together. In some embodiments, manual addition involves moving the mold from the oven, removing a vent tube or plug that creates an opening in the part and adding more material using a funnel or wand. This operation can be repeated for each additional layer. In some embodiments, a drop-box typically comprises the material for a particular layer and it is an insulated container that holds material until it is released at the appropriate time during the cycle. The signal for release of material can be usually transmitted as a pressure pulse via the airline through the arm of the machine. The insulation can be kept cool to prevent the material inside the box from melting. The present disclosure also contemplates a method for rotomolding articles having one or more layers, the method comprising the steps of (and according to the processes steps known to persons skilled in the art): a) feeding at least one thermoplastic composition as described herein for at least one layer into a mold; b) placing the fdled mold in pre-heated oven; c) rotating the fdled mold about two perpendicular axes; d) feeding the thermoplastic composition described herein or another thermoplastic composition for at least one additional layer (i.e. second layer, a third layer, etc.), followed by repeating steps (b) and (c) for each additional layer; and finally, e) cooling the mold and retrieving the rotomolded article from the mold.

[0218] Non-limiting examples of articles which can be made using a rotomolding process include custom tanks, water tanks, carts, transportation cases and containers, coolers, as well as sports and recreation equipment (e.g. boats, kayaks), toys, and playground equipment.

[0219] The desired physical properties of rotomolded articles depend on the application of interest. Non-limiting examples of desired properties may include one or more of: flexural modulus (1% and 2% secant modulus); environmental stress crack resistance (ESCR); shore hardness; heat deflection temperature (HDT); VICAT softening point; IZOD impact strength; ARM impact resistance; and color (whiteness and / or yellowness index). In an embodiment of the disclosure a process for making a rotomolded article comprises the following steps: (i) charging a thermoplastic composition into a mold; (ii) heating the mold in an oven to a temperature of more than 280°C; (iii) rotating the mold around at least 2 axes; (iv) cooling the mold while the mold is rotating; and (v) opening the mold to release the rotomolded article.

[0220] Further non-limiting details of the disclosure are provided in the following examples. The examples are presented for the purposes of illustrating selected embodiments of this disclosure, it being understood that the examples presented do not limit the claims presented.

[0221] EXAMPLES

[0222] Prior to testing, each specimen was conditioned for at least 24 hours at 23 ±2°C and 50 ±10% relative humidity and subsequent testing was conducted at 23 ±2°C and 50 ±10% relative humidity, unless otherwise specified. Herein, the term “ASTM conditions” refers to a laboratory that is maintained at 23 ±2°C and 50 ±10% relative humidity; and specimens to be tested were conditioned for at least 24 hours in this laboratory prior to testing. ASTM refers to the American Society for Testing and Materials.

[0223] Density

[0224] Polyethylene composition densities were determined using ASTM D792-13 (November 1, 2013).

[0225] Melt Index

[0226] The polyethylene composition melt index was determined using ASTM D1238 (August 1, 2013). Melt indexes, h, h, Iio and hi were measured at 190°C, using weights of 2.16 kg, 6.48 kg, 10 kg and a 21.6 kg respectively. Herein, the term “stress exponent” or its acronym “S.Ex ”, is defined by the following relationship:

[0227] S.Ex.= log (l6 / h) / log(6480 / 2160) wherein h and h are the melt flow rates measured at 190°C using 6.48 kg and 2.16 kg loads, respectively. In this disclosure, melt index was expressed using the units of g / 10 minutes or g / 10 min or dg / minutes or dg / min; these units are equivalent.

[0228] Gel Permeation Chromatography (GPC)

[0229] Polyethylene composition molecular weights, Mn, Mwand Mz, in g / mol, as well the as the polydispersity (Mw / Mn), were determined using ASTM D6474-12 (Dec. 15, 2012). Polymer sample solutions (1 to 2 mg / mL) were prepared by heating the polymer in 1,2,4- trichlorobenzene (TCB) and rotating on a wheel for 4 hours at 150°C in an oven. The antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT) was added to the mixture in order to stabilize the polymer against oxidative degradation. The BHT concentration was 250 ppm. Sample solutions were chromatographed at 140°C on a PL 220 high-temperature chromatography unit equipped with four Shodex columns (HT803, HT804, HT805 and HT806) using TCB as the mobile phase with a flow rate of 1.0 mL / minute, with a differential refractive index (DRI) as the concentration detector. BHT was added to the mobile phase at a concentration of 250 ppm to protect GPC columns from oxidative degradation. The sample injection volume was 200 pL. The GPC raw data were processed with the Cirrus GPC software. The GPC columns were calibrated with narrow distribution polystyrene standards. The polystyrene molecular weights were converted to polyethylene molecular weights using the Mark-Houwink equation, as described in ASTM D6474-12 (Dec. 15, 2012).

[0230] Comonomer Content: Fourier Transform Infrared (FTIR) Spectroscopy

[0231] The quantity of comonomer in a polyethylene composition was determined by FTIR and reported as the Short Chain Branching (SCB) content having dimensions of CH3# / 1000C (number of methyl branches per 1000 carbon atoms). This test was completed according to ASTM D6645-01 (2001), employing a compression molded polymer plaque and a Thermo-Nicolet 750 Magna-IR Spectrophotometer. The polymer plaque was prepared using a compression molding device (Wabash-Genesis Series press) according to ASTM D4703-16 (April 2016). GPC-FTIR

[0232] Polyethylene composition (polymer) solutions (2 to 4 mg / mL) were prepared by heating the polymer in 1,2,4-trichlorobenzene (TCB) and rotating on a wheel for 4 hours at 150°C in an oven. The antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT) was added to the mixture in order to stabilize the polymer against oxidative degradation. The BHT concentration was 250 ppm. Sample solutions were chromatographed at 140°C on a Waters GPC 150C chromatography unit equipped with four Shodex columns (HT803, HT804, HT805 and HT806) using TCB as the mobile phase with a flow rate of 1.0 mL / minute, with a FTIR spectrometer and a heated FTIR flow through cell coupled with the chromatography unit through a heated transfer line as the detection system. BHT was added to the mobile phase at a concentration of 250 ppm to protect SEC columns from oxidative degradation. The sample injection volume was 300 pL. The raw FTIR spectra were processed with OPUS FTIR software and the polymer concentration and methyl content were calculated in real time with the Chemometric Software (PLS technique) associated with the OPUS. Then the polymer concentration and methyl content were acquired and baseline-corrected with the Cirrus GPC software. The SEC columns were calibrated with narrow distribution polystyrene standards. The polystyrene molecular weights were converted to polyethylene molecular weights using the Mark-Houwink equation, as described in the ASTM standard test method D6474. The comonomer content was calculated based on the polymer concentration and methyl content predicted by the PLS technique as described in Paul J. DesLauriers, Polymer 43, pages 159-170 (2002); herein incorporated by reference.

[0233] The GPC-FTIR method measures total methyl content, which includes the methyl groups located at the ends of each macromolecular chain, i.e. methyl end groups. Thus, the raw GPC-FTIR data must be corrected by subtracting the contribution from methyl end groups. To be more clear, the raw GPC-FTIR data overestimates the amount of short chain branching (SCB) and this overestimation increases as molecular weight (M) decreases. In this disclosure, raw GPC-FTIR data was corrected using the 2-methyl correction. At a given molecular weight (M), the number of methyl end groups (NE) was calculated using the following equation; NE = 28000 / M, and NE (M dependent) was subtracted from the raw GPC-FTIR data to produce the SCB / 1000C (2 -Methyl Corrected) GPC-FTIR data. Unsaturation Content

[0234] The quantity of unsaturated groups, i.e., double bonds, in polyethylene composition was determined according to ASTM D3124-98 (vinylidene unsaturation, published March 2011) and ASTM D6248-98 (vinyl and trans unsaturation, published July 2012). A polymer sample was: a) first subjected to a carbon disulfide extraction to remove additives that may interfere with the analysis; b) the sample (pellet, film or granular form) was pressed into a plaque of uniform thickness (0.5 mm); and c) the plaque was analyzed by FTIR.

[0235] Composition Distribution Branching Index (CDBI) by CTREF

[0236] The “Composition Distribution Branching Index” or “CDBI” of the disclosed Examples and Comparative Examples were determined using a crystal-TREF unit (a “CTREF” unit) commercially available form Polymer Char (Valencia, Spain). The acronym “TREF” refers to Temperature Rising Elution Fractionation. A sample of polyethylene composition (80 to 100 mg) was placed in the reactor of the Polymer Char crystal-TREF unit, the reactor was filled with 35 ml of 1,2,4-trichlorobenzene (TCB), heated to 150°C and held at this temperature for 2 hours to dissolve the sample. An aliquot of the TCB solution (1.5 mb) was then loaded into the Polymer Char TREF column filled with stainless steel beads and the column was equilibrated for 45 minutes at 110°C. The polyethylene composition was then crystallized from the TCB solution, in the TREF column, by slowly cooling the column from 110°C to 30°C using a cooling rate of 0.09°C per minute. The TREF column was then equilibrated at 30°C for 30 minutes. The crystallized polyethylene composition was then eluted from the TREF column by passing pure TCB solvent through the column at a flow rate of 0.75 mL / minute as the temperature of the column was slowly increased from 30°C to 120°C using a heating rate of 0.25°C per minute. Using Polymer Char software, a TREF distribution curve was generated as the polyethylene composition was eluted from the TREF column, i.e., a TREF distribution curve is a plot of the quantity (or intensity) of polymeric material eluting from the column as a function of TREF elution temperature. A CDBEo was calculated from the TREF distribution curve for each polyethylene composition analyzed. The “CDBEo” is defined as the percent of polymer whose composition is within 50% of the median comonomer composition (25% on each side of the median comonomer composition); it is calculated from the TREF composition distribution curve and the normalized cumulative integral of the TREF composition distribution curve. Those skilled in the art will understand that a calibration curve is required to convert a TREF elution temperature to comonomer content, i.e., the amount of comonomer in the polyethylene composition fraction that elutes at a specific temperature. The generation of such calibration curves are described in the prior art, e.g., Wild, et al., J. Polym. Sci., Part B, Polym. Phys., Vol. 20 (3), pages 441-455. Dynamic Mechanical Analysis (DMA)

[0237] Oscillatory shear measurements under small strain amplitudes were carried out to obtain linear viscoelastic functions at 190°C under N2 atmosphere, at a strain amplitude of 10% and over a frequency range of 0.02-126 rad / s at 5 points per decade. Frequency sweep experiments were performed with a TA Instruments DHR3 stress-controlled rheometer using cone-plate geometry with a cone angle of 5°, a truncation of 137 pm and a diameter of 25 mm. In this experiment a sinusoidal strain wave was applied and the stress response was analyzed in terms of linear viscoelastic functions. The zero shear rate viscosity (r|o) based on the DMA frequency sweep results was predicted by Ellis model (see R.B. Bird et al. “Dynamics of Polymer Liquids. Volume 1: Fluid Mechanics” Wiley-Interscience Publications (1987) p.228) or Carreau-Yasuda model (see K. Yasuda (1979) PhD Thesis, IT Cambridge). The dynamic rheological data were analyzed using the rheometer software (viz., Rheometrics RHIOS V4.4 or Orchestrator Software) to determine the melt elastic modulus G'(G"=500) at a reference melt viscous modulus (G") value of G"=500 Pa. If necessary, the values were obtained by interpolation between the available data points using the Rheometrics software. The term “Storage modulus”, G'(co), also known as “elastic modulus”, which is a function of the applied oscillating frequency, co, is defined as the stress in phase with the strain in a sinusoidal deformation divided by the strain; while the term “Viscous modulus”, G"(co), also known as “loss modulus”, which is also a function of the applied oscillating frequency, co, is defined as the stress 90 degrees out of phase with the strain divided by the strain. Both these moduli, and the others linear viscoelastic, dynamic rheological parameters, are well known within the skill in the art, for example, as discussed by G. Marin in “Oscillatory Rheometry”, Chapter 10 of the book on Rheological Measurement, edited by A. A. Collyer and D. W. Clegg, Elsevier, 1988.

[0238] The shear thinning index, SHI(i,ioo) was calculated as the ratio of the complex viscosities estimated at shear stress of 1 kPa over that estimated at a shear stress of 100 kPa. The shear thinning index, SHI(i.ioo) provides information on the shear thinning behavior of the polymer melt. A high value indicates a strong dependence of viscosity with changes in deformation rate (shear or frequency).

[0239] The evaluation of relative elasticity is based on measurements carried out at low frequencies, which are most relevant for conditions associated with powder sintering and densification in rotomolding. The relative elasticity is evaluated based on the ratio of G' over G" at a frequency of 0.05 rad / s (or 0.5 rad / s) from DMA frequency sweep measurements carried out at 190°C. Data reported in the literature show that resin compositions with a high relative elasticity tend to exhibit processing difficulties in terms of slow powder densification. Wang and Kontopoulou (2004) reported adequate rotomoldability for blend compositions that were characterized with a relative elasticity as high as 0.125. In that study, the effect of plastomer content on the rotomoldability of polypropylene was investigated (W.Q. Wang and M. Kontopoulou (2004) Polymer Engineering and Science, vo. 44, no 9, pp 1662-1669). Further analysis of the results published by Wang and Kontopoulou show that compositions with higher plastomer content exhibited increasing relative elasticity (G7G">0.13) and correspondingly increasing difficulties in achieving full densification during rotomolding evaluation.

[0240] Melt Strength

[0241] The melt strength is measured on Rosand RH-7 capillary rheometer (barrel diameter = 15mm) with a flat die of 2 -mm Diameter, L / D ratio 10: 1 at 190°C. Pressure Transducer: 10,000 psi (68.95 MPa). Piston Speed: 5.33 mm / min. Haul-off Angle: 52°. Haul-off incremental speed: 50 - 80 m / min2or 65 ± 15 m / min2. A polymer melt is extruded through a capillary die under a constant rate and then the polymer strand is drawn at an increasing haul -off speed until it ruptures. The maximum steady value of the force in the plateau region of a force versus time curve is defined as the melt strength for the polymer. The melt strength stretch ratio is defined as the ratio of the velocity at pulley over the velocity at the exit of the die.

[0242] Impact Properties

[0243] IZOD impact performance was determined according to ASTM D256. IZOD impact specimens were notched to promote a stress concentration point to induce a brittle, rather than ductile, break. Tensile impact performance was determined according to ASTM D1822.

[0244] Tensile Properties

[0245] The following tensile properties were determined using ASTM D 638: elongation at yield (%), yield strength (MPa), ultimate elongation (%), ultimate strength (MPa) and 1 and 2% secant modulus (MPa).

[0246] Flexural Properties

[0247] Flexural properties, i.e., 2% flexural secant modulus was determined using ASTM D790-10 (published in April 2010).

[0248] Environmental Stress Crack Resistance, ESCR

[0249] Plaques molded from the polyethylene compositions were tested according to the following ASTM methods: Bent Strip Environmental Stress Crack Resistance (ESCR), ASTM D 1693 ; ESCR test under the “B” conditions of ASTM D 1693 (at a temperature of 50°C) were conducted using a 100% solution of IGEPAL CO-630 (nonylphenoxy poly(ethyleneoxy)ethanol, branched; having the formula: 4-(branched-C9Hi9)-phenyl- [OCH2CH2]n-OH, wherein subscript n is 9-10 ) and using a 10% solution of IGEPAL CO- 630. It will be recognized by skilled persons that the test using the 10% solution (“Bio”) is more severe than the test using the 100% solution (“Bioo”); i.e. that Bio values are typically lower than Bioo values.

[0250] Plaques molded from the polyethylene compositions were tested according to the following ASTM methods: Bent Strip Environmental Stress Crack Resistance (ESCR), ASTM D1693; ESCR test under the “A” conditions of ASTM D1693 (at a temperature of 50°C) were conducted using a 100% solution of IGEPAL CO-630 (nonylphenoxy poly(ethyleneoxy)ethanol, branched having the formula: 4-(branched-C9Hi9)-phenyl- [OCH2CH2]n-OH, wherein subscript n is 9-10 ) and using a 10% solution of IGEPAL CO- 630. It will be recognized by skilled persons that the test using the 10% solution (“Aio”) is more severe than the test using the 100% solution (“Aioo”); i.e. that Bio values are typically lower than Aioo values.

[0251] Preparation of the Polyethylene Compositions

[0252] Polyethylene compositions were made using an “in-series” dual reactor solution polymerization process. A single site catalyst was used to polymerize ethylene and optionally an alpha olefin in each of a first and a second polymerization reactor, R1 and R2 respectively. As a result, a polyethylene composition comprised a first polyethylene component which was made with a single site catalyst and a second polyethylene component which was also made with a single site catalyst system.

[0253] A relevant “in series” dual reactor, solution phase polymerization process, including one employing a single site catalyst system in each reactor has been described in U.S. Pat. No 8,908,018. Basically, in an “in-series” dual reactor system the exit stream from a first polymerization reactor (Rl) flows directly into a second polymerization reactor (R2). The R1 pressure was from about 14 MPa to about 18 MPa; while R2 was operated at a lower pressure to facilitate continuous flow from Rl to R2. Both Rl and R2 were continuously stirred reactors (CSTR’s) and were agitated to give conditions in which the reactor contents were well mixed. The process was operated continuously by feeding fresh process solvent, ethylene, 1 -octene and hydrogen to the reactors and in the removal of product (note however, that 1 -octene is only feed to the first reactor). Although no co-monomer is feed directly to the downstream second reactor, R2 an ethylene copolymer is nevertheless formed in second reactor due to the significant presence of un-reacted 1 -octene flowing from the first reactor to the second reactor where it is copolymerized with ethylene. Methylpentane was used as the process solvent (a commercial blend of methylpentane isomers). The volume of the first CSTR reactor (Rl) was 3.2 gallons (12 L), and the volume of the second CSTR reactor (R2) was 5.8 gallons (22 L). Monomer (ethylene) and comonomer (1 -octene) were purified prior to addition to the reactor using conventional feed preparation systems (such as contact with various absorption media to remove impurities such as water, oxygen and polar contaminants). The reactor feeds were pumped to the reactors at the ratios shown in Table 1. Average residence times for the reactors are calculated by dividing average flow rates by reactor volume and is primarily influenced by the amount of solvent flowing through each reactor and the total amount of solvent flowing through the solution process.

[0254] In the first reactor, Rl, the following single site catalyst components were used to prepare the first polyethylene component: cyclopentadienyltri(tertiarybutyl)phosphinimine titanium dichloride, Cp((t-Bu)3PN)TiCh; methylaluminoxane (MMAO-07); trityl tetrakis(pentafluoro-phenyl)borate, “ trityl borate”; and 2,6-di-tert-butyl-4-ethylphenol (BHEB). Methylaluminoxane (MMAO-07) and 2,6-di-tert-butyl-4-ethylphenol (BHEB) are premixed in-line and then combined with Cp((t-Bu)3PN)TiC12 and trityl borate just before entering the polymerization reactor (Rl). The efficiency of the single site catalyst system was optimized by adjusting the mole ratios of the catalyst components and the Rl catalyst inlet temperature.

[0255] In the second reactor, R2, the following single site catalyst components were used to prepare the second polyethylene component: cyclopentadienyltri(tertiarybutyl)phosphinimine titanium dichloride, Cp((t-Bu)3PN)TiCh; methylaluminoxane (MMAO-07); trityl tetrakis(pentafluoro-phenyl)borate, “ trityl borate”; and 2, 6-di -tert-butyl -4-ethylphenol (BHEB). Methylaluminoxane (MMAO-07) and 2,6-di- tert-butyl-4-ethylphenol (BHEB) are premixed in-line and then combined with Cp((t- Bu)3PN)TiCh and trityl borate just before entering the polymerization reactor (Rl). The efficiency of the single site catalyst system was optimized by adjusting the mole ratios of the catalyst components and the Rl catalyst inlet temperature.

[0256] Polymerization in the continuous solution polymerization process was terminated by adding a catalyst deactivator to the second reactor exit stream. The catalyst deactivator used was octanoic acid (caprylic acid), commercially available from P&G Chemicals, Cincinnati, OH, U.S.A. The catalyst deactivator was added such that the moles of fatty acid added were 50% of the total molar amount of hafnium, titanium and aluminum added to the polymerization process; to be clear, the moles of octanoic acid added = 0.5 x (moles hafnium + moles titanium + moles aluminum).

[0257] A two-stage devolatilization process was employed to recover the ethylene interpolymer product from the process solvent, i.e. two vapor / liquid separators were used and the second bottom stream (from the second V / L separator) was passed through a gear pump / pelletizer combination. DHT®-4V (hydrotalcite), supplied by Kyowa Chemical Industry Co. LTD, Tokyo, Japan was used as a passivator, or acid scavenger, in the continuous solution process. A slurry of DHT-4V in process solvent was added prior to the first V / L separator.

[0258] Prior to pelletization the polyethylene composition was stabilized by adding one or more antioxidant compound(s). Antioxidants were dissolved in process solvent and added between the first and second V / L separators.

[0259] Tables 1 provides properties of the polyethylene composition used in the present disclosure. Tables 1 also provides properties of plaques made from the polyethylene composition used in the present disclosure. Table 2 provides data for a deconvolution analysis of the polyethylene composition in which the properties of its first and second polyethylene components are estimated.

[0260] Mathematical deconvolutions were performed to determine the relative amounts of each of the first and second ethylene copolymers present in a polyethylene composition, as well as the molecular weights (Mw, Mn, Mz), and comonomer content (the SCB frequency per 1000 polymer backbone carbon atoms) of each of the first and second ethylene copolymers made in the first and second reactors (Rl, and R2).

[0261] For the deconvolution calculations it was assumed that the single-site catalyzed ethylene copolymer components follow a Flory molecular weight distribution function and they have a homogeneous comonomer distribution across the whole molecular weight range.

[0262] Estimates were first obtained from predictions obtained using fundamental kinetic models with kinetic constants specific for each catalyst formulation as well as feed and reactor conditions. The simulation was based on the configuration of a solution pilot plant as described above and which was used to produce the polyethylene compositions disclosed herein. The kinetic model predictions were used to establish estimates of the short chain branching distribution within the first and second ethylene copolymer components. The estimated values for short branches content were also validated against experimental results obtained from GPC-FTIR for the comonomer distribution. The fit between the simulated molecular weight distribution profile and the actual data obtained from GPC chromatography was improved by modeling the molecular weight distribution as a sum of components which have molecular weight distributions described using multiple-site idealized Flory distributions.

[0263] During the deconvolution, the overall Mn, Mw and Mz are calculated using the following relationships: Mn = l / (wi / (Mn)i), Mw = (wi x (Mw)i), Mz = (wi x (Mz)i2 / (wi x (Mzi) where i represents the i-th component and wi represents the relative weight fraction of the i-th component in the composition.

[0264] The following equations were used to calculate the densities and melt index, h of each ethylene copolymer component: Equation (1) l = 0.978863 - 5.94808 X > 3.83133 X 025

[0265] 10-4[log10(Mn)]3- 5.77986 5.57395 ' Equation (2) 2 = ( - w1p1) / w2

[0266] Equation (3) log10(Melt Index I2) = 7.900 - 3.909 [log10(^)] - 0.2799 where Mn, Mw, Mz, and SCB / 1000C are the deconvoluted values of the individual ethylene polymer components, as obtained from the results of the deconvolution described above, while p is the density of the overall polyethylene composition and is determined experimentally. Equations (1) and (2) were used to estimate pl and p2, the density of the first and second ethylene copolymers, respectively. Equation (3) was used to estimate the melt index, L of the first and second ethylene copolymers, respectively. See for example, Alfred Rudin, in The Elements of Polymer Science and Engineering, 2nd edition, Academic Press, 1999 and U.S. Pat. No. 8,022,143. The deconvolution results are provided in Table 2.

[0267] TABLE 1

[0268] Polyethylene Composition Properties

[0269] TABLE 2

[0270] Polyethylene Composition Deconvolution

[0271] Polyethylene Composition Compounding (The Thermoplastic Composition)

[0272] The polyethylene composition described above was used to prepare thermoplastic compositions containing an additive package. Such a polyethylene composition is commercially available from NOVA Chemicals as RMs-341-U and has a density of 0.941 g / cm3, a melt index, h of 3.5, and is comprised a first polyethylene component which was an ethylene copolymer of polymerized ethylene and 1 -octene, and a second polyethylene component which was an ethylene copolymer of polymerized ethylene and 1 -octene.

[0273] Melt extrusion methods were used to incorporate various additives into the polyethylene composition to give a thermoplastic composition which could be assessed for rotomolding performance.

[0274] Thermoplastic compositions were prepared by melt compounding the polyethylene composition with the additive(s) REVONOX 501, which is a benzo-furanone antioxidant compound commercially available from the Chitec Technology Company, and optionally IRGANOX 1010 which is a hindered phenolic antioxidant commercially available from BASF Corporation, using an Egan Gala 3.5 inch single screw extruder. The final compounded formulations (i.e. the thermoplastic compositions), as well as a control polyethylene composition (note: the same polyethylene composition was used in the control but was not compounded with either of REVONOX 501 or IRGANOX 1010) are shown in Table 3.

[0275] TABLE 31

[0276] Thermoplastic Compositions

[0277] Note 1 : The number refers to the parts per million, ppm of the additive based on the weight of the polyethylene composition. The compounded polyethylene compositions (i.e. the thermoplastic compositions) shown in Table 3 were ground into fine powder (35 -mesh) prior to use in the formation of a rotomolded part (that is, prior to rotomolding, the compounded polyethylene compositions were passed through a grinder such that a powder of the thermoplastic composition was produced having 35 US mesh size (mesh opening of 0.0197 inch (500 pm)). Rotomolded Part Preparation

[0278] The powdered thermoplastic compositions were converted into rotomolded parts employing a rotational molding machine; specifically, a Rotospeed RS 160 available from Ferry Industries Inc. (Stow, Ohio, USA). The Rotospeed has two arms which rotate about a central axis within an enclosed oven. The arms are fitted with plates which rotate on an axis that is roughly perpendicular to the axis of rotation of the arm. Each arm is fitted with six cast aluminum molds that produce a hollow rotomolded part of cubical shape, i.e.: 12.5 inches (31.8 cm)x l2.5 inches / 12.5 inches. The arm rotation was set to about 8 revolutions per minute (rpm) and the plate rotation was set to about 2 rpm. Rotomolded parts having a nominal thickness of about 0.250 inches (0.64 cm) were produced employing a standard charge of about 3.7 kg of a polyethylene composition in powder form, where the powder has a 35 US mesh size (mesh opening of 0.0197 inch (500 pm)). The temperature within the enclosed oven was maintained at a temperature of 560°F (293°C). The molds and their contents were heated in the oven for 22, 24, 26, 28, 30, and 32 minutes to evaluate the rotomolding process window for each thermoplastic composition. The molds were subsequently cooled using air fans for about 30 minutes prior to removing the part from the mold. Following the removal of the plastic part from the mold, the parts were kept as is at room temperature for at least 24 hours prior to being cut in order to collect specimens for subsequent testing. Specimens were collected from the molded parts for to perform ARM Impact testing.

[0279] ARM Impact Testing

[0280] The ARM impact test was performed in accordance with ASTM D5628, at a test temperature of -40°C. This test was adapted from the Association of Rotational Molders International, Eow Temperature Impact Test, Version 4.0 dated July 2003. The purpose of this test was to determine the impact properties of a rotomolded part. ARM Impact test specimens, 5 inchx5 inch (12.7 cmx 12.7 cm) were cut from a side wall of the cubical rotomolded part. Test specimens were thermally equilibrated in a refrigerated testing laboratory maintained at -40°F.±3.5°F (-40°C ±2°C) for at least 24 hours prior to impact testing. The testing technique employed is commonly called the Bruceton Staircase Method or the Up-and-Down Method. Samples were impact tested using a drop weight impact tester; impact darts available consisted of 10 lb (4.54 kg), 15 lb (6.80 kg), 20 lb (9.07 kg) or 30 lb (13.6 kg) darts. All impact darts had a rounded dart tip having a diameter of 1.0±0.005 inch (2.54 cm), the dart tip transitioned into a lower cylindrical shaft (1.0 inch diameter), the length of the lower cylindrical shaft (to dart tip) was 4.5 inch (11.4 cm). The impact dart included an upper cylindrical shaft having a diameter of 2.0 inch (5.08 cm), the length of the upper cylinder shaft varied depending on the desired weight of the dart, e.g. 10.5 inch (26.7 cm) or 16.5 inch (41.9 cm) for the 10 lb or 20 lb dart, respectively.

[0281] Preferably a dart weight is selected such that the drop height is between 2.5 ft and 7.5 ft (0.8 m to 2.3 m). Test specimens were oriented in the impact tester such that the falling dart impacted the surface of the part that was in contact with the mold (when molded). If the sample did not fail at a given height and weight, either the height or weight was increased incrementally until part failure occurred. Once failure occurred, the height or weight is decreased by the same increment and the process is repeated. The procedure establishes the height of a specific dart that will cause 50% of the specimens to fail, i.e. testing (dart falling on specimens) was carried out until there was a minimum of 10 passes and 10 fails. Each failure was characterized as a ductile or a brittle failure.

[0282] Ductile failure was characterized by penetration of the dart though the specimen and the impact area was elongated and thinned leaving a hole with stringy fibers at the point of failure. Brittle failure was evident when the test specimen cracked, where the cracks radiated outwardly from point of failure and the sample showed very little to no elongation at the point of failure. The “ARM Ductility %” was calculated as follows: 100% x [(number of ductile failure s) / (total number of all failures: ductile + brittle)]. For rotomolded articles a ductile failure is considered the desired failure mode: hence, the “ARM Impact Percent Ductility” corresponds to the percentage of the failures that are ductile, rather than brittle; if there are no brittle failures the ARM % ductility will be 100% (favorable) and if the failures are all brittle the ARM % ductility will be 0% (unfavorable).

[0283] The “ARM Mean Failure Energy (ft- lbs)” was calculated by multiplying the drop height (ft) by the nominal dart weight (lbs). After impact, both the upper and lower surface of the specimen were inspected for failure.

[0284] The results of the ARM Impact testing are shown in Table 4 and in Figures 1 and 2.

[0285] A “color index” defines a measurement of color, e.g. a number that correlates with an observer's perception of a color, where the observer has normal color vision. Nonlimiting examples of color indexes, include “a Whiteness Index (WI)” and “a Yellowness Index (YI)”; and in this disclosure WI and YI may be measured according to ASTM E313- 10. The results of a rotomolded part colour determination after various oven times, and using the yellowness index, YI, are provided in Figure 3. The yellowness index, YI was determined for a rotomolded specimen, or an “as-is” part, and was carried out using a Hunter LabScan XE spectrophotometer.

[0286] TABLE 4

[0287] Thermoplastic Compositions

[0288] The data in Table 4, also plotted in Figures 1 and 2, show that a thermoplastic composition comprising the benzo-furanone compound, REVONOX 501, optionally together with IRGANOX 1010, had a significantly reduced impact knee and hence a broadened rotomolding process window. The data in Table 4 and Figures 1 and 2 shows that the mean failure energy impact knee was entirely mitigated while for brittle failure the impact knee was significantly reduced (the ductile failure, which is the preferred method of failure, was never less than about 35 percent and not less than about 60 percent for most oven times). The process times at which brittle failure begins to occur was also delayed by up to about 4 minutes relative to the control. Hence, the mean failure energy and the brittle failure percentage were both significantly improved over all oven times, relative to the control example, which is highly advantageous for rotomolded article manufacturing.

[0289] As shown in Figure 3, the use of the benzo-furanone antioxidant compound REVONOX 501, optionally in combination with a hindered phenolic antioxidant compound such as IRGANOX 1010 in a polyethylene composition led to rotomolded parts having poorer yellowness index than those prepared from a control polyethylene composition. Further work to optimize loading levels of the benzo-furanone compound, or its combination with other additives may help to improve these color issues. For example, using lower levels of REVONOX 501 may prove to be an effective way to improve the yellowness index, the “YI” of the rotomolded article while maintaining sufficient impact performance.

[0290] Non-limiting embodiments of the present disclosure include the following: We claim: Embodiment 1. A thermoplastic composition for use in a rotomolding process, the thermoplastic composition comprising: a) a polyethylene composition having a melt index, h of from 0.5 to 10 g / lOmin and a density of from 0.930 to 0.965 g / cm3, the polyethylene composition comprising: a first polyethylene component which is an ethylene copolymer; and a second polyethylene component which is an ethylene homopolymer or an ethylene copolymer; wherein the first polyethylene component has a weight average molecular weight, Mw1which is higher than a weight average molecular weight, Mw2of the second polyethylene component; and b) an additive package comprising a benzo-furanone antioxidant compound having the formula I: wherein n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; and R3 is independently a Ci-Cs alkyl group or a OH group.

[0291] Embodiment 2. The thermoplastic composition of Embodiment 1, wherein the additive package comprises from 50 to 4,000 ppm (based on the weight of the polyethylene composition) of the benzo-furanone antioxidant compound.

[0292] Embodiment 3. The thermoplastic composition of Embodiment 1 or 2, wherein benzo-furanone antioxidant compound has the formula III:

[0293] Embodiment 4. The thermoplastic composition of Embodiment 1, 2 or 3 wherein the polyethylene composition has a density of from 0.932 to 0.960 g / cm3.

[0294] Embodiment 5. The thermoplastic composition of Embodiment 1, 2, 3, or 4 wherein the polyethylene composition has a melt index, h of from 1.0 to 10 g / lOmin.

[0295] Embodiment 6. The thermoplastic composition of Embodiment 1, 2, 3, 4, or 5 wherein the first polyethylene component is present in from 5 to 75 weight percent, the second polyethylene component is present in from 95 to 25 weight percent, wherein the weight percent of the first or second polyethylene component is defined as the weight of the first or second polyethylene component divided by the weight of the sum of the first polyethylene component and the second polyethylene component, multiplied by 100%.

[0296] Embodiment 7. The thermoplastic composition of Embodiment 1, 2, 3, 4, or 5 wherein the first polyethylene component is present in from 20 to 50 weight percent, the second polyethylene component is present in from 80 to 50 weight percent, wherein the weight percent of the first or second polyethylene component is defined as the weight of the first or second polyethylene component divided by the weight of the sum of the first polyethylene component and the second polyethylene component, multiplied by 100%.

[0297] Embodiment 8. The thermoplastic composition of Embodiment 1, 2, 3, 4, 5, 6, or 7 wherein the first polyethylene component has a weight average molecular weight, Mw1of at least 100,000 g / mol.

[0298] Embodiment 9. The thermoplastic composition of Embodiment 1, 2, 3, 4, 5, 6, 7, or 8 wherein the first polyethylene component is an ethylene copolymer comprising polymerized ethylene and 1 -octene.

[0299] Embodiment 10. The thermoplastic composition of Embodiment 1, 2, 3, 4, 5, 6, 7, 8, or 9 wherein the second polyethylene component has a weight average molecular weight, Mw2of less than 90,000 g / mol. Embodiment 11. The thermoplastic composition of Embodiment 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 wherein the second polyethylene component is an ethylene copolymer comprising polymerized ethylene and 1 -octene.

[0300] Embodiment 12. The thermoplastic composition of Embodiment 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11 wherein the second polyethylene component is an ethylene homopolymer.

[0301] Embodiment 13. The thermoplastic composition of Embodiment 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 wherein the first polyethylene component has a short chain branching content, SCB1 per 1000 carbon backbone atoms, which is greater than a short chain branching content, SCB2 per 1000 carbon backbone atoms, in the second polyethylene component.

[0302] Embodiment 14. The thermoplastic composition of Embodiment 1, 2, 3, 4, 5, 6, 7,

[0303] 8, 9, 10, 11, 12, or 13 wherein the second polyethylene component has a density, d2, which is greater than a density, dl, of the first polyethylene component.

[0304] Embodiment 15. The thermoplastic composition of Embodiment 1, 2, 3, 4, 5, 6, 7, 8,

[0305] 9, 10, 11, 12, 13, or 14 wherein the additive package further comprises at least one compound selected from the group consisting of: a hindered phenolic antioxidant compound; a phosphite antioxidant compound; a phosphonite antioxidant compound; a metal oxide compound; a hindered amine light stabilizer; a hydroxylamine compound; and mixtures thereof.

[0306] Embodiment 16. A rotomolded article prepared from the thermoplastic composition of any one of Embodiments 1 to 15.

[0307] Embodiment 17. A rotomolding process for making a rotomolded article, the process comprising: preparing a thermoplastic composition by combining a polyethylene composition with an additive package; adding the thermoplastic composition to a mold; heating the mold; rotating the mold about at least 2 axes of rotation; cooling the mold; and removing the rotomolded article from the mold; wherein the polyethylene composition has a melt index, h of from 0.5 to 10 g / lOmin and a density of from 0.930 to 0.965 g / cm3, and comprises: a first polyethylene component which is an ethylene copolymer; and a second polyethylene component which is an ethylene homopolymer or an ethylene copolymer; wherein the first polyethylene component has a weight average molecular weight, Mw1which is higher than a weight average molecular weight, Mw2of the second polyethylene component; and wherein the additive package comprises a benzo-furanone antioxidant compound having the formula I: wherein n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; and R3 is independently a Ci-Cs alkyl group or a OH group.

[0308] Embodiment 18. The rotomolding process of Embodiment 17, wherein the additive package comprises from 50 to 4,000 ppm (based on the weight of the polyethylene composition) of the benzo-furanone antioxidant compound. Embodiment 19. The rotomolding process of Embodiment 17 or 18, wherein benzo- furanone antioxidant compound has the formula (III): Embodiment 20. The rotomolding process of Embodiment 17, 18 or 19 wherein the polyethylene composition has a density of from 0.932 to 0.960 g / cm3, the polyethylene.

[0309] Embodiment 21. The rotomolding process of Embodiment 17, 18, 19, or 20 wherein the polyethylene composition has a melt index, h of from 1.0 to 10 g / lOmin.

[0310] Embodiment 22. The rotomolding process of Embodiment 17, 18, 19, 20, or 21 wherein the first polyethylene component is present in from 5 to 75 weight percent, the second polyethylene component is present in from 95 to 25 weight percent, wherein the weight percent of the first or second polyethylene component is defined as the weight of the first or second polyethylene component divided by the weight of the sum of the first polyethylene component and the second polyethylene component, multiplied by 100%.

[0311] Embodiment 23. The rotomolding process of Embodiment 17, 18, 19, 20, or 21 wherein the first polyethylene component is present in from 20 to 50 weight percent, the second polyethylene component is present in from 80 to 50 weight percent, wherein the weight percent of the first or second polyethylene component is defined as the weight of the first or second polyethylene component divided by the weight of the sum of the first polyethylene component and the second polyethylene component, multiplied by 100%.

[0312] Embodiment 24. The rotomolding process of Embodiment 17, 18, 19, 20, 21, 22, or 23 wherein the first polyethylene component has a weight average molecular weight, Mw1of at least 100,000 g / mol.

[0313] Embodiment 25. The rotomolding process of Embodiment 17, 18, 19, 20, 21, 22, 23, or 24 wherein the first polyethylene component is an ethylene copolymer comprising polymerized ethylene and 1 -octene.

[0314] Embodiment 26. The rotomolding process of Embodiment 17, 18, 19, 20, 21, 22,

[0315] 23, 24, or 25 wherein the second polyethylene component has a weight average molecular weight, Mw2of less than 90,000 g / mol.

[0316] Embodiment 27. The rotomolding process of Embodiment 17, 18, 19, 20, 21, 22, 23,

[0317] 24, 25, or 26 wherein the second polyethylene component is an ethylene copolymer comprising polymerized ethylene and 1 -octene.

[0318] Embodiment 28. The rotomolding process of Embodiment 17, 18, 19, 20, 21, 22, 23, 24, 25, 26 or 27 wherein the second polyethylene component is an ethylene homopolymer.

[0319] Embodiment 29. The rotomolding process of Embodiment 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, or 28 wherein the first polyethylene component has a short chain branching content, SCB1 per 1000 carbon atoms, which is greater than a short chain branching content, SCB2 per 1000 carbon atoms, in the second polyethylene component.

[0320] Embodiment 30. The rotomolding process of Embodiment 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, or 29 wherein the second polyethylene component has a density, d2, which is greater than a density, dl, of the first polyethylene component.

[0321] Embodiment 31. The rotomolding process of Embodiment 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 wherein the additive package further comprises at least one compound selected from the group consisting of: a hindered phenolic antioxidant compound; a phosphite antioxidant compound; a phosphonite antioxidant compound; a metal oxide compound; a hindered amine light stabilizer; a hydroxylamine compound; and mixtures thereof.

[0322] Embodiment 32. A rotomolded article prepared according to the rotomolding process of any one of Embodiments 1-31.

[0323] INDUSTRIAL APPLICABILITY A thermoplastic polyethylene composition contains an additive package which expands process conditions over which a rotomolded article can be made.

Claims

CLAIMS1. A thermoplastic composition for use in a rotomolding process, the thermoplastic composition comprising: a) a polyethylene composition having a melt index, L of from 0.5 to 10 g / lOmin and a density of from 0.930 to 0.965 g / cm3, the polyethylene composition comprising: a first polyethylene component which is an ethylene copolymer; and a second polyethylene component which is an ethylene homopolymer or an ethylene copolymer; wherein the first polyethylene component has a weight average molecular weight, Mw1which is higher than a weight average molecular weight, Mw2of the second polyethylene component; and b) an additive package comprising a benzo-furanone antioxidant compound having the formula I:wherein n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; and R3 is independently a Ci-Cs alkyl group or a OH group.

2. The thermoplastic composition of claim 1, wherein the additive package comprises from 50 to 4,000 ppm (based on the weight of the polyethylene composition) of the benzo- furanone antioxidant compound.

3. The thermoplastic composition of claim 1, wherein benzo-furanone antioxidant compound has the formula III:

4. The thermoplastic composition of claim 1 wherein the polyethylene composition has a density of from 0.932 to 0.960 g / cm3.

5. The thermoplastic composition of claim 1 wherein the polyethylene composition has a melt index, h of from 1.0 to 10 g / lOmin.

6. The thermoplastic composition of claim 1 wherein the first polyethylene component is present in from 5 to 75 weight percent, the second polyethylene component is present in from 95 to 25 weight percent, wherein the weight percent of the first or second polyethylene component is defined as the weight of the first or second polyethylene component divided by the weight of the sum of the first polyethylene component and the second polyethylene component, multiplied by 100%.

7. The thermoplastic composition of claim 1 wherein the first polyethylene component is present in from 20 to 50 weight percent, the second polyethylene component is present in from 80 to 50 weight percent, wherein the weight percent of the first or second polyethylene component is defined as the weight of the first or second polyethylene component divided by the weight of the sum of the first polyethylene component and the second polyethylene component, multiplied by 100%.

8. The thermoplastic composition of claim 1 wherein the first polyethylene component has a weight average molecular weight, Mw1of at least 100,000 g / mol.

9. The thermoplastic composition of claim 1 wherein the first polyethylene component is an ethylene copolymer comprising polymerized ethylene and 1 -octene.

10. The thermoplastic composition of claim 1 wherein the second polyethylene component has a weight average molecular weight, Mw2of less than 90,000 g / mol.

11. The thermoplastic composition of claim 1 wherein the second polyethylene component is an ethylene copolymer comprising polymerized ethylene and 1 -octene.

12. The thermoplastic composition of claim 1 wherein the second polyethylene component is an ethylene homopolymer.

13. The thermoplastic composition of claim 1 wherein the first polyethylene component has a short chain branching content, SCB1 per 1000 carbon backbone atoms, which is greater than a short chain branching content, SCB2 per 1000 carbon backbone atoms, in the second polyethylene component.

14. The thermoplastic composition of claim 1 wherein the second polyethylene component has a density, d2, which is greater than a density, dl, of the first polyethylene component.

15. The thermoplastic composition of claim 1 wherein the additive package further comprises at least one compound selected from the group consisting of: a hindered phenolic antioxidant compound; a phosphite antioxidant compound; a phosphonite antioxidant compound; a metal oxide compound; a hindered amine light stabilizer; a hydroxylamine compound; and mixtures thereof.

16. A rotomolded article prepared from the thermoplastic composition of any one of claims 1 to 15.

17. A rotomolding process for making a rotomolded article, the process comprising: preparing a thermoplastic composition by combining a polyethylene composition with an additive package; adding the thermoplastic composition to a mold; heating the mold; rotating the mold about at least 2 axes of rotation; cooling the mold; and removing the rotomolded article from the mold; wherein the polyethylene composition has a melt index, h of from 0.5 to 10 g / lOmin and a density of from 0.930 to 0.965 g / cm3, and comprises: a first polyethylene component which is an ethylene copolymer; and a second polyethylene component which is an ethylene homopolymer or an ethylene copolymer; wherein the first polyethylene component has a weight average molecular weight, Mw1which is higher than a weight average molecular weight, Mw2of the second polyethylene component; andwherein the additive package comprises a benzo-furanone antioxidant compound having the formula I:wherein n = 0, 1, 2, or 3; Ri and R2 are independently a Ci-Cs alkyl group; and R3 is independently a Ci-Cs alkyl group or a OH group.

18. The rotomolding process of claim 17, wherein the additive package comprises from 50 to 4,000 ppm (based on the weight of the polyethylene composition) of the benzo- furanone antioxidant compound.

19. The rotomolding process of claim 17, wherein benzo-furanone antioxidant compound has the formula (III):

20. The rotomolding process of claim 17, wherein the polyethylene composition has a density of from 0.932 to 0.960 g / cm3, the polyethylene.

21. The rotomolding process of claim 17, wherein the polyethylene composition has a melt index, I2 of from 1.0 to 10 g / lOmin.

22. The rotomolding process of claim 17, wherein the first polyethylene component is present in from 5 to 75 weight percent, the second polyethylene component is present in from 95 to 25 weight percent, wherein the weight percent of the first or second polyethylenecomponent is defined as the weight of the first or second polyethylene component divided by the weight of the sum of the first polyethylene component and the second polyethylene component, multiplied by 100%.

23. The rotomolding process of claim 17, wherein the first polyethylene component is present in from 20 to 50 weight percent, the second polyethylene component is present in from 80 to 50 weight percent, wherein the weight percent of the first or second polyethylene component is defined as the weight of the first or second polyethylene component divided by the weight of the sum of the first polyethylene component and the second polyethylene component, multiplied by 100%.

24. The rotomolding process of claim 17, wherein the first polyethylene component has a weight average molecular weight, Mw1of at least 100,000 g / mol.

25. The rotomolding process of claim 17, wherein the first polyethylene component is an ethylene copolymer comprising polymerized ethylene and 1 -octene.

26. The rotomolding process of claim 17, wherein the second polyethylene component has a weight average molecular weight, Mw2of less than 90,000 g / mol.

27. The rotomolding process of claim 17, wherein the second polyethylene component is an ethylene copolymer comprising polymerized ethylene and 1 -octene.

28. The rotomolding process of claim 17, wherein the second polyethylene component is an ethylene homopolymer.

29. The rotomolding process of claim 17, wherein the first polyethylene component has a short chain branching content, SCB1 per 1000 carbon atoms, which is greater than a short chain branching content, SCB2 per 1000 carbon atoms, in the second polyethylene component.

30. The rotomolding process of claim 17, wherein the second polyethylene component has a density, d2, which is greater than a density, dl, of the first polyethylene component.

31. The rotomolding process of claim 17, wherein the additive package further comprises at least one compound selected from the group consisting of: a hindered phenolic antioxidant compound; a phosphite antioxidant compound; a phosphonite antioxidant compound; a metal oxide compound; a hindered amine light stabilizer; a hydroxylamine compound; and mixtures thereof.

32. A rotomolded article prepared according to the rotomolding process of any one of claims 17 to 31.

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