Patent Description:
Polyethylenes, and especially linear low density polyethylenes (LLDPE), are widely used in daily life. These materials have particular utility in packaging due to their low cost and high performance. The use of single site LLDPEs in film applications is often considered beneficial, as these materials tend to offer improved mechanical properties over LLDPE produced using a Ziegler Natta catalyst. One of the drawbacks of this type of material is its processability however. Single site produced LLDPEs often have narrow molecular weight distribution and hence are more challenging to extrude and film blow.

A known solution to that problem is to blend low density polyethylene (LDPE) with the LLDPE to improve the stability of the bubble during film blowing. This combination also offers improved optical properties. However, the introduction of LDPE reduces the mechanical performance of the film and its sealing properties. The present inventors sought a solution to this problem, which provides an ideal balance of good processability and good optics without a reduction in mechanical performance and sealing properties.

The present inventors have established that a film comprising the combination of a single site produced LLDPE and an ethylene alkyl (meth)acrylate offers a solution to this problem. These two materials have previous been combined in various fields.

<CIT> discloses the combination of LLDPE and ethylene ethyl acrylate in the field of solar cells.

<CIT> discloses a blend of plastomer type polyethylene and EEA in the context of flooring and dent resistance.

<CIT> and <CIT> concern a cling film comprising a plastomer type polyethylene and ethylene alkyl (meth)acrylate.

Films comprising a combination of a single site produced LLDPE copolymer as defined herein with an ethylene alkyl (meth)acrylate offer a preferred solution with an ideal balance of optical, mechanical and sealing properties which combination is readily processable.

Viewed from one aspect the invention provides a film comprising.

Viewed from another aspect the invention provides a multilayer film comprising at least two layers wherein at least one layer comprises.

Viewed from another aspect the invention provides a process for the production of a film comprising (a) combining.

(b) extruding and blowing or casting said mixture to form a film or one layer of a multilayer film.

Viewed from another aspect the invention provides the use of a film as hereinbefore defined in packaging, such as food packaging.

The weight percentages above are based on the total weight of the film or film layer respectively.

The term ethylene alkyl (meth)acrylate is a copolymer of ethylene and an alkyl methacrylate or alkyl acrylate.

This invention relates to a film or a film layer in a film comprising a LLDPE copolymer and an ethylene alkyl (meth)acrylate copolymer. This combination of components has been found to surprisingly lead to an excellent balance of processability, optical properties, mechanical properties and sealing properties.

The LLDPE copolymer used in the invention is one that is manufactured using a single site catalyst. Alternatively viewed the LLDPE copolymer of use in the invention is one that comprises residues of Hf or Zr which derive from the catalyst used to prepare it.

The LLDPE copolymer used in the films of the present invention is a LLDPE copolymer having a density of <NUM> to <NUM>/m<NUM>. Typically, the density is in the range of <NUM> to <NUM>/m<NUM>, especially as <NUM> to <NUM>/m<NUM>. A highly preferred density range is <NUM> to <NUM>/m<NUM>.

The melt flow rate (<NUM>, <NUM>) (MFR<NUM>) of the LLDPE copolymer is in the range of <NUM> to <NUM> /<NUM>, preferably from <NUM> to <NUM>/<NUM>, more preferably from <NUM> to <NUM>/<NUM>. The use of a LLDPE copolymer having a density of <NUM> to <NUM>/m<NUM> and a MFR<NUM> of <NUM> to <NUM>/<NUM> is especially preferred.

The LLDPE copolymer is preferably a copolymer of ethylene with one or more alpha-olefin comonomers having from <NUM> to <NUM> carbon atoms. Ideally, the comonomer(s) present are selected from the group consisting of is <NUM>-butene, <NUM>-hexene or <NUM>-octene.

The LLDPE copolymer may contain from <NUM> to <NUM>% by mole of comonomer(s), e.g. from <NUM> to <NUM>% by mole of comonomer(s). For example, the LLDPE copolymer may contain from <NUM> to <NUM> % by mole, preferably from <NUM> to <NUM> % by mole, of units derived from ethylene and from <NUM> to <NUM> % by mole of units derived from the comonomer(s), the comonomer(s) preferably being one or more alpha-olefins having from <NUM> to <NUM> carbon atoms.

The LLDPE copolymer of use in the invention is preferably multimodal, such as bimodal. By multimodal LLDPE copolymer is meant a copolymer which contains at least two distinct components having different average molecular weights, different contents of comonomer or both. Ideally, the GPC curve of such a material will show two distinct peaks. Multimodal LLDPE copolymers are well known and are widely described in the literature.

It is preferred that the LLDPE copolymer used has a molecular weight distribution (Mw/Mn) in the range of <NUM> to <NUM>, more preferably in the range of from <NUM> to <NUM>, most preferably in the range of from <NUM> to <NUM>.

The LLDPE copolymer preferably has a melting point of <NUM> to <NUM>, more preferably of <NUM> to <NUM> and even more preferably of <NUM> to <NUM>.

The amount of component (i) in any film, film layer or blend of the invention is at least <NUM> wt%, such as at least <NUM> wt%, especially at least <NUM> wt%, such as <NUM> to <NUM> wt%. These percentages are based on the total weight of the film, film layer or blend of the invention.

In one embodiment, the LLDPE copolymer is a multimodal LLDPE terpolymer of ethylene and at least two alpha-olefin comonomers having from <NUM> to <NUM> carbon atoms. The term terpolymer is used herein to define a LLDPE polymer with at least two comonomers.

Ideally, the multimodal LLDPE terpolymer comprises a first copolymer component of ethylene and an alpha-olefin comonomer having from <NUM> to <NUM> carbon atoms and a second copolymer component of ethylene and an alpha-olefin comonomer having from <NUM> to <NUM> carbon atoms. These components are obviously different. Preferably, the multimodal LLDPE terpolymer is a copolymer of ethylene and at least two comonomers selected from <NUM>-butene, <NUM>-hexene, and <NUM>-octene. Ideally, the comonomers used in the two components are different.

It is further preferred that the multimodal LLDPE terpolymer is a terpolymer of ethylene and exactly two comonomers preferably selected from <NUM>-butene, <NUM>-hexene, or <NUM>-octene. Especially preferred is a multimodal LLDPE terpolymer comprising.

Even more preferred is a multimodal LLDPE terpolymer comprising.

The multimodal LLDPE terpolymer of the present invention is preferably produced by copolymerizing ethylene and at least two comonomers in two or more polymerization stages where the polymerization conditions are sufficiently different to allow production of different polymers in different stages. Such polymers are described in, inter alia, <CIT>. Full details of how to prepare suitable multimodal LLDPE terpolymers can be found in this reference.

A preferred multimodal LLDPE terpolymer comprises a first copolymer component and a second copolymer component.

The first copolymer component preferably comprises ethylene and a first alpha-olefin comonomer having <NUM> to <NUM> carbon atoms, such as <NUM>-butene, <NUM>-hexene or <NUM>-octene, more preferably <NUM>-butene. In a preferred embodiment, the first copolymer component consists of ethylene and <NUM>-butene.

The first copolymer component may have a MFR<NUM> of <NUM> to <NUM>/<NUM>. Furthermore, the first copolymer component may have a density of from <NUM> to <NUM>/m<NUM>, preferably <NUM> to <NUM>/m<NUM>, especially <NUM> to <NUM>/m<NUM>, most especially from <NUM> to <NUM>/m<NUM>.

The first copolymer component is ideally produced in a first polymerization stage, which is preferably a slurry polymerization. Hydrogen can be introduced into the first polymerization stage for controlling the MFR<NUM> of the first copolymer component.

The first alpha-olefin comonomer is introduced into the first polymerization stage for controlling the density of the first copolymer component. As discussed above, the comonomer is an alpha-olefin having from <NUM> to <NUM> carbon atoms, preferably <NUM>-butene, <NUM>-hexene or <NUM>-octene, more preferably <NUM>-butene.

In a most preferred embodiment, the multimodal LLDPE terpolymer comprises a first and a second copolymer component, wherein the first copolymer component comprises at least a first and a second fraction.

These two or more fractions of the first copolymer component may be unimodal in view of their molecular weight or they can be bimodal in respect of their molecular weight.

It is preferred that the two or more fractions of the first copolymer component are unimodal in view of their molecular weight.

It is within the scope of the invention, that the first and the second fraction of the first copolymer component are present in a weight ratio of <NUM>:<NUM> up to <NUM>:<NUM>, such as <NUM>:<NUM> to <NUM>:<NUM>, or <NUM>:<NUM> to <NUM>:<NUM>, or <NUM>:<NUM>.

Each fraction of the first copolymer component is a polyethylene copolymer with one or more alpha-olefins having from <NUM> to <NUM> carbon atoms, preferably <NUM>-butene, <NUM>-hexene or <NUM>-octene, more preferably <NUM>-butene. Ideally, each fraction contains a single comonomer. Ideally, each fraction is an ethylene <NUM>-butene copolymer.

It is further preferred, that the two or more fractions of the first copolymer component are produced in two or more consecutive reactors. Ideally, the fractions are produced in two consecutive slurry reactors such as loop reactors.

For a person skilled in the art it will be clear that when producing the first and the second fraction of the first copolymer component in two consecutive reactors, there has to be a certain difference in the MFR<NUM>-values and/or density-values of each fraction to ensure that these can be distinguished. These must be different.

It is hence understood within the meaning of the invention, that MFR<NUM> after loop1 is preferably higher than the MFR<NUM> after loop2 of the first copolymer component. Further, the MFR<NUM> after loop2 can be at least <NUM>% lower than the MFR<NUM> after loop1. Ideally, the density after loop2 is lower than that after loop1, e.g. at least <NUM>/m<NUM> lower. Alternatively viewed therefore the MFR<NUM> of the first and second fractions differs by at least <NUM>/<NUM>. Alternatively viewed therefore the density of the first and second fractions differs by at least <NUM>/m<NUM>.

The second copolymer component comprises ethylene and a second alpha-olefin comonomer having <NUM> to <NUM> carbon atoms, such as <NUM>-hexene or <NUM>-octene, more preferably <NUM>-hexene. It is further preferred that the second alpha-olefin comonomer has more carbon atoms than the first alpha-olefin monomer, i.e. the comonomer in the second copolymer component is higher than the comonomer in the first copolymer component, e.g. <NUM>-hexene vs <NUM>-butene.

It is further preferred that the second alpha-olefin comonomer has <NUM> more carbon atoms than the first alpha-olefin monomer. In a preferred embodiment the second copolymer consists of ethylene and <NUM>-hexene.

The second copolymer component is produced in the presence of any previously produced polymer component. Ideally, it is produced in a gas phase reactor, e.g. as discussed in <CIT>.

The ratio (i.e. the split) between the first and the second copolymer within the multimodal LLDPE terpolymer of ethylene and at least two alpha-olefin-comonomers has significant effect on the mechanical properties of the final composition.

It is hence envisaged within the scope of the invention that the second copolymer component forms a significant part of the polymer components present in the multimodal LLDPE terpolymer, i.e. at least <NUM> wt% of the multimodal LLDPE terpolymer, preferably <NUM> wt% or more, such as <NUM> wt% or more.

More preferably the second copolymer component may form up to <NUM> wt% of the multimodal LLDPE terpolymer.

Consecutively the first copolymer component forms at most <NUM> wt% or less of the multimodal LLDPE terpolymer, preferably <NUM> wt% or less, such as <NUM> wt% or less. More preferably the first copolymer component may form <NUM> wt% or more of the multimodal LLDPE terpolymer.

The second copolymer ideally represents a higher molecular weight component whereas the first copolymer ideally represents a lower molecular weight component. The MFR of the second copolymer is preferably lower therefore than that of the first copolymer.

The multimodal LLDPE terpolymer is preferably produced in a loop loop gas cascade. Such polymerization steps may be preceded by a prepolymerization step. The purpose of the prepolymerization is to polymerize a small amount of polymer onto the catalyst at a low temperature and/or a low monomer concentration. By prepolymerization it is possible to improve the performance of the catalyst in slurry and/or modify the properties of the final polymer. The prepolymerization step is preferably conducted in slurry.

The catalyst components are preferably all introduced to the prepolymerization step when a prepolymerization step is present. However, where the solid catalyst component and the cocatalyst can be fed separately it is possible that only a part of the cocatalyst is introduced into the prepolymerization stage and the remaining part into subsequent polymerization stages. Also in such cases it is necessary to introduce so much cocatalyst into the prepolymerization stage that a sufficient polymerization reaction is obtained therein.

It is understood within the scope of the invention, that the amount of polymer produced in the prepolymerization lies within <NUM> to <NUM> wt% in respect to the final multimodal LLDPE terpolymer. This can counted as part of the first copolymer component.

The LLDPE copolymer is one made using a single site catalyst, such as a metallocene catalyst. A metallocene catalyst comprises a metallocene complex and a cocatalyst. It is preferred if the metallocene complex comprises an element of a group (IV) metal coordinated to at least one, preferably at least two cyclopentadienyl type ligands.

The cyclopentadienyl type group ligand has been widely described in the scientific and patent literature for about twenty years. Essentially any ligand containing the general structure:
<CHM>
can be employed herein.

The cyclopentadienyl type ligand can be an unsubstituted or substituted and/or fused cyclopentadienyl ligand, e.g. substituted or unsubstituted cyclopentadienyl, substituted or unsubstituted indenyl, substituted or unsubstituted tetrahydroindenyl or substituted or unsubstituted fluorenyl ligand.

Suitable ligands therefore include:
<CHM>
<CHM>
<CHM>
which can obviously be substituted. The metallocene complex preferably does not comprise a single cyclopentadienyl type ligand. Preferably, two such cyclopentadienyl type ligands are present, ideally joined by a bridging group. The substitution pattern on the two ligands may be the same or different. Metallocene complexes of use in this invention can therefore be symmetrical or asymmetrical.

The two cyclopentadienyl ligands of the present invention can be bridged or unbridged as is well known in the art. It is generally envisaged that the principles of this invention can be applied to any bis cyclopentadienyl type ligand system.

The metallocene complex will comprise at least one metal ion of group (IV) as is well known. This will be η-bonded to the cyclopentadienyl type rings. Such η-bonded metals are typically Zr, Hf or Ti, especially Zr or Hf.

In a preferred embodiment the metallocene complex is a compound of formula (I).

n is <NUM> or <NUM>;
M is a transition metal of Group <NUM>, e.g. Ti, Zr or Hf, especially Zr or Hf. In a preferred embodiment the metallocene complex is a compound of formula (II).

Suitably, in each X as -CH<NUM>-Y, each Y is independently selected from C6-C20-aryl, NR"<NUM>, -SiR"<NUM> or -OSiR"<NUM>. Most preferably, X as -CH<NUM>-Y is benzyl. Each X other than -CH<NUM>-Y is independently halogen, C1-C20-alkyl, C1-C20-alkoxy, C6-C20-aryl, C7-C20-arylalkenyl or -NR"<NUM> as defined above, e.g. -N(C1-C20-alkyl)<NUM>.

Preferably, each X is halogen, methyl, phenyl or -CH<NUM>-Y, and each Y is independently as defined above.

Cp is preferably cyclopentadienyl, indenyl, tetrahydroindenyl or fluorenyl, optionally substituted as defined above.

Ideally Cp is a cyclopentadienyl or indenyl. In a suitable subgroup of the compounds of formula (I), each Cp independently bears <NUM>, <NUM>, <NUM> or <NUM> substituents as defined above, preferably <NUM>, <NUM> or <NUM>, such as <NUM> or <NUM> substituents, which are preferably selected from C1-C20-alkyl, C6-C20-aryl, C7-C20-arylalkyl (wherein the aryl ring alone or as a part of a further moiety may further be substituted as indicated above), -OSiR"<NUM>, wherein R" is as indicated above, preferably C1-C20-alkyl.

R, if present, is preferably a methylene, ethylene or a silyl bridge, whereby the silyl can be substituted as defined above, e.g. a (dimethyl)Si=, (methylphenyl)Si=, (methyylcyclohexyl)silyl= or (trimethylsilylmethyl)Si=; n is <NUM> or <NUM>. Preferably, R" is other than hydrogen.

A specific subgroup includes the well-known metallocenes of Zr, Hf and Ti with two eta5-ligands which may be bridged or unbridged cyclopentadienyl ligands optionally substituted with e.g. siloxy, or alkyl (e.g. C1-<NUM>-alkyl) as defined above, or with two unbridged or bridged indenyl ligands optionally substituted in any of the ring moieties with e.g. siloxy or alkyl as defined above, e.g. at <NUM>-, <NUM>-, <NUM>- and/or <NUM>-positions. Preferred bridges are ethylene or -SiMe<NUM>.

The preparation of the metallocenes can be carried out according or analogously to the methods known from the literature and is within skills of a person skilled in the field. Thus for the preparation see e.g. <CIT>, examples of compounds wherein the metal atom bears a -NR"<NUM> ligand see i. in <CIT> and <CIT>. For the preparation see also e.g. in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

To form a catalyst, a cocatalyst is used as is well known in the art. Cocatalysts comprising Al or B are well known and can be used here. The use of aluminoxanes (e.g. MAO) or boron based cocatalysts (such as borates) is preferred.

LLDPE copolymers made using single site catalysis, as opposed to Ziegler Natta catalysis, have characteristic features that allow them to be distinguished from Ziegler Natta materials. In particular, the comonomer distribution is more homogeneous. This can be shown using TREF or Crystaf techniques. Catalyst residues may also indicate the catalyst used. Ziegler Natta catalysts would not contain a Zr or Hf group (IV) metal for example.

The ethylene alkyl (meth)acrylate copolymer of the invention is preferably an ethylene C<NUM>- to C<NUM>-alkyl acrylate copolymer, or ethylene C<NUM>- to C<NUM>-alkyl methacrylate copolymer. Still more preferably, said ethylene alkyl (meth)acrylate copolymer is a copolymer of ethylene with C<NUM>- to C<NUM>-alkyl acrylate, such as methyl, ethyl, propyl or butyl acrylate. The use of ethylene methyl acrylate (EMA), ethylene ethyl acrylate (EEA), or ethylene butyl acrylate (EBA) is preferred.

In one embodiment, the ethylene alkyl (meth)acrylate copolymer is an ethylene ethyl (meth)acrylate copolymer, ethylene methyl (meth)acrylate copolymer or ethylene butyl (meth)acrylate copolymer.

The alkyl (meth)acrylate content of the ethylene alkyl (meth)acrylate copolymer may range from <NUM> to <NUM> wt%, such as <NUM> to <NUM> wt%, more preferably <NUM> to <NUM> wt%, especially <NUM> to <NUM> wt%. These percentages are based on the content of the alkyl (meth)acrylate comonomer in the polymer as a whole.

Preferably, the ethylene alkyl (meth)acrylate copolymer has a melt flow rate MFR<NUM> (<NUM>/<NUM>) of <NUM> to <NUM>/<NUM>, more preferably <NUM> to <NUM>/<NUM>, even more preferably <NUM> to <NUM>/<NUM>, and most preferably <NUM> to <NUM>/<NUM>.

Preferably, the ethylene alkyl (meth)acrylate copolymer may have a density of <NUM> to <NUM>/m<NUM>, such as <NUM> to <NUM>/m<NUM>.

The amount of component (ii) in any film, film layer or blend of the invention is <NUM> to <NUM> wt%, such as <NUM> to 25wt%, especially <NUM> to <NUM> wt% such as <NUM> to <NUM> wt%. These percentages are based on the total weight of the film, film layer or blend of the invention.

The blend of components (i) and (ii) as defined herein form a still yet further aspect of the invention. Thus, viewed from another aspect the invention provides a blend comprising.

Any preferred option for component (i) or (ii) described above also applies to this embodiment.

The film of the invention may be a monolayer film or a multilayer film. In a multilayer film, one or more layers of that film may comprise a blend of components (i) and (ii) as herein defined. In a monolayer film, the film itself comprises the defined amounts of components (i) and (ii).

The film of the invention or a layer of a multilayer film may comprise <NUM> to <NUM> wt% of component (i) and <NUM> to <NUM> wt% of the component (ii).

Films of the invention may also comprise standard polymer additives such as antistatic agent, an antioxidant, an acid scavenger, a nucleating agent and so on. In particular phenolic stabilizers, antioxidants, slip and antistatic agents, antiblock agents processing aids, colorants and the like might be present. These typically form less than <NUM> wt% of the film or layer of the film, such as less than <NUM> wt%.

A film of the invention such as a monolayer or multilayer film, may have a Dart drop index of at least <NUM>, such as <NUM> to <NUM>.

A film of the invention may have a machine direction (MD) tear resistance of at least <NUM> N/mm and/or a transverse direction (TD) tear resistance of at least <NUM> N/mm.

A film of the invention may have a thickness of <NUM> to <NUM>, such as <NUM> to <NUM>.

Films of the invention are preferably non oriented films.

Films of the invention have utility in the field of packaging. The films can be used to package food products or non-perishable products.

Multilayer films may comprise two, three or five layers, even up to seven layers. At least one layer of such films comprises components (i) and (ii) as defined herein, especially an outer sealing layer of such a film. Other layers in multilayer films can comprise other polyethylenes, e.g. HDPE, plastomers etc. It is preferred that films of the invention contain only polyethylene polymers.

Films of the invention may perform as shrink films, collation shrink films, wrap films, lamination films, etc..

The invention further relates to a process for the preparation of a film comprising (a) combining.

This film manufacturing process may additionally comprise a process for the preparation of a single site produced linear low density polyethylene (LLDPE) copolymer. In one embodiment therefore, before the process defined above there is a process for the preparation of a single site linear low density polyethylene (LLDPE) copolymer comprising polymerizing ethylene and at least one C3-<NUM> alpha-olefin comonomer in the presence of a single site catalyst.

In particular that process is a process for the preparation of a multimodal LLDPE terpolymer comprising at least two C4-<NUM> comonomers, said process comprising:.

Preferably, the multimodal LLDPE terpolymer is a copolymer of ethylene and at least two comonomers selected from <NUM>-butene, <NUM>-hexene, and <NUM>-octene.

The first step of this process is ideally effected in the slurry phase, e.g. in a loop reactor.

The second step of this process is ideally effected in the slurry phase, e.g. in a loop reactor.

The first step of this process may be preceding by a prepolymerization step.

The third step of this process is ideally effected in the gas phase.

In a most preferred embodiment, the process of the invention may also comprise a process for the preparation of a multimodal LLDPE terpolymer comprising:.

The invention will now be described with reference to the following non limiting examples.

Density of the polyethylene was measured according to ISO <NUM>-<NUM>:<NUM> (method A) on compression moulded specimen prepared according to EN ISO <NUM>-<NUM> (Feb <NUM>) and is given in kg/m<NUM>.

The melt flow rate (MFR) is determined according to ISO <NUM> and is indicated in g/<NUM>. The MFR is an indication of the flowability, and hence the processability, of the polymer / polyethylene for specific conditions. The higher the melt flow rate, the lower the viscosity of the polymer / polyethylene. The MFR is determined at <NUM> for polyethylene and at a loading of <NUM> (MFR<NUM>), <NUM> (MFR<NUM>) or <NUM> (MFR<NUM>).

Was measured according to ASTM D1003 on <NUM> micron films.

The method determines the sealing temperature range (sealing range) of polyethylene films, in particular blown films or cast films. The sealing temperature range is the temperature range, in which the films can be sealed according to conditions given below.

The lower limit (heat sealing initiation temperature (SIT)) is the sealing temperature at which a sealing strength of > <NUM> N is achieved. The upper limit (sealing end temperature (SET)) is reached, when the films stick to the sealing device.

The sealing range is determined on a J&B Universal Sealing Machine Type <NUM> with a film of <NUM> thickness with the following further parameters:.

The hot-tack force was determined according to ASTM F <NUM>-<NUM> - Method B on a J&B Hot-Tack Tester on a <NUM> thickness film. All film test specimens were prepared in standard atmospheres for conditioning and testing at <NUM> (± <NUM>) and <NUM> % (± <NUM> %) relative humidity. The minimum conditioning time of test specimen in standard atmosphere before start testing is at least <NUM>. The minimum storage time between extrusion of film sample and start testing is at least <NUM>. The hot tack measurement determines the strength of heat seals formed in the films, immediately after the seal has been made and before it cools to ambient temperature. The hot-tack measurement was performed under the following conditions.

The hot tack force was measured as a function of temperature within the temperature range and with temperature increments as indicated above. The number of test specimens were at least <NUM> specimens per temperature. The Hot Tack force is evaluated as the highest force (maximum peak value) with failure mode "peel".

Dart-drop is measured using ASTM D1709, method A (Alternative Testing Technique) from the film samples. A dart with a <NUM> diameter hemispherical head is dropped from a height of <NUM> onto a film clamped over a hole. Successive sets of twenty specimens are tested. One weight is used for each set and the weight is increased (or decreased) from set to set by uniform increments. The weight resulting in failure of <NUM> % of the specimens is calculated and reported.

DDI<NUM> denominates the Dart Drop Impact determined on a <NUM> blown film.

Tensile moduli in machine/transverse direction were determined acc. to ISO <NUM>-<NUM> on films with a thickness of <NUM> at a cross head speed of <NUM>/min.

Applies both for the measurement in machine direction (MD) and transverse direction (TD) on <NUM> film. The tear strength is measured using the ISO <NUM>/<NUM> method. The force required to propagate tearing across a film sample is measured using a pendulum device. The pendulum swings under gravity through an arc, tearing the specimen from pre-cut slit. The film sample is fixed on one side by the pendulum and on the other side by a stationary clamp. The tear resistance is the force required to tear the specimen. The relative tear resistance (N/mm) is then calculated by dividing the tear resistance by the thickness of the film.

<NUM> grams of a metallocene complex bis(<NUM>-methyl-<NUM>-n-butylcyclopentadienyl) zirconium (IV) dichloride (<NPL>) and <NUM> of a <NUM>% solution of commercial methylalumoxane (MAO) in toluene were combined and <NUM> dry purified toluene was added. Thus, obtained complex solution was added onto <NUM> silica carrier Sylopol <NUM> SJ (supplied by Grace) by very slow uniform spraying over <NUM> hours. The temperature was kept below <NUM>. The mixture was allowed to react for <NUM> hours after complex addition at <NUM>.

The LLDPE used was obtained via the following process, i.e. in a Borstar pilot plant comprising a prepolymerization step - loop - loop - gas phase reactor cascade, e.g. as described in <CIT>. It is a multimodal LLDPE terpolymer comprising first and second copolymer components wherein the first copolymer component comprises two fractions.

FT5230 is an unmodified low density polyethylene based on the tubular technology for film extrusion. It is produced by Borealis. It has MFR<NUM> of <NUM>,<NUM>/<NUM> and density of <NUM>/m<NUM>.

Ethylene ethyl acrylate copolymer (EEA) OE3216, has an ethyl acrylate content of <NUM> wt% and MFR<NUM> of <NUM>/<NUM>. It is commercially produced by Borealis.

The monolayer film was produced on Collin <NUM> blow film lab line, with <NUM> thickness and <NUM>:<NUM> BUR.

As can be seen, the IE1 has similar stiffness (TM) but much higher DDI and tear in both directions. The films have comparable haze. The optomechanical ability (OMA) is determined according the formula given below: <MAT>.

The OMA is a reflection of the balance between the stiffness, impact and optical properties of an article. The IE has much higher OMA value than CE, indicating the IE has more balanced properties.

Claim 1:
A film, such as a monolayer film, comprising
(i) at least <NUM> wt% based on the total weight of the film of a single site produced linear low density polyethylene (LLDPE) copolymer having an MFR<NUM> (ISO <NUM> at <NUM>, <NUM>) of <NUM> to <NUM>/<NUM> and a density (ISO <NUM>) of <NUM> to <NUM>/m<NUM>; and
(ii) <NUM> to <NUM> wt% based on the total weight of the film of an ethylene alkyl (meth)acrylate copolymer having an alkyl (meth)acrylate content of <NUM> to <NUM> wt% based on the total weight of the ethylene alkyl (meth)acrylate copolymer.