EP3870442A1

EP3870442A1 - Multi-layered article with improved adhesion

Info

Publication number: EP3870442A1
Application number: EP19789692.1A
Authority: EP
Inventors: Daniel Van Houcke
Original assignee: Abu Dhabi Polymers Co Ltd Borouge LLC; Borealis AG
Current assignee: Abu Dhabi Polymers Co Ltd Borouge LLC; Borealis AG
Priority date: 2018-10-26
Filing date: 2019-10-22
Publication date: 2021-09-01
Also published as: WO2020083902A1; CN112930260A; MY194659A

Abstract

The present invention relates to a multi-layered article comprising at least two layers (A) and (B) in adherent contact with each other, wherein layer (A) comprises polymer composition (PC-A) comprising an ethylene-vinyl alcohol copolymer, and layer (B) comprises a polymer composition (PC-B) comprising a polyolefin and from 1.0 to 15.0 wt% of a non-polar thermoplastic elastomer modified with polar groups, and the use of said non-polar thermoplastic elastomer modified with polar groups for improving adhesion between said layers (A) and (B) in said multi-layered article.

Description

Multi-layered article with improved adhesion

The present invention relates to a multi-layered article comprising at least two layers (A) and (B) in adherent contact with each other, wherein layer (B) comprises a 5 polymer composition comprising from 1.0 to 15 wt% of a non-polar thermoplastic elastomer modified with polar groups and the use of said non-polar thermoplastic elastomer modified with polar groups for improving adhesion between the at least two layers (A) and (B). 0 Background of the invention

In packaging technology multi-layered articles such as films or sheets have become common which consist of distinct layers that are barriers for oxygen and moisture. Thereby, polyolefins such as polyethylenes or polypropylenes act as excellent moisture barriers with only very limited barrier properties for oxygen, aromatics and5 oils.

On the other hand, ethylene- vinyl alcohol (EVOH) copolymers possess excellent barrier properties to oxygen, aromatics and oils but is highly sensitive to moisture. Consequently, the properties of polyolefins and EVOH copolymers are combined in commercial packaging application such as for food, drugs or cosmetics by

0 coextruding multi-layered articles containing EVOH resins as oxygen barrier layer and polyolefin layers as moisture barrier layers, whereby usually the polyolefin layers sandwich an EVOH core layer.

Because of the chemical dissimilarities between the polyolefins and the EVOH, however, an extrudable adhesive polymer must be incorporated in the multi-layered5 article as a tie-layer that promotes adhesion between the polyolefin layers and the EVOH layer.

However, having additional tie layers in a coextruded multi-layered article makes the fabrication process more complex and expensive.

Three-layer structures have been developed comprising a EVOH core layer

0 sandwiched by two low density polyethylene (LDPE) layers which include as

adhesion promotor low density polyethylene grafted with maleic anhydride (LDPE- g-MAH) (Huang et al. Polymer Journal, Vol. 35, No. 12, p. 978-984). However, high amounts of adhesion promotor are needed to significantly improve the adhesion and the films show insufficient mechanical properties.

Milacron Holdings Corp. developed a three layer transparent can based on EVOH core layer sandwiched by two polypropylene based layers in order to replace aluminium cans. Analysis of said can shows that adhesion between the layers is still poor.

Thus, there is a need in the art for multi-layered articles with good moisture barrier and oxygen barrier properties which show improved adhesion and mechanical properties without need of tie layers.

Summary of the invention

The present invention relates to a multi-layered article comprising at least two layers (A) and (B) in adherent contact with each other, wherein

layer (A) comprises polymer composition (PC-A) comprising an ethylene- vinyl alcohol copolymer, and

layer (B) comprises a polymer composition (PC-B) comprising a polyolefin and from 1.0 to 15.0 wt% of a non-polar thermoplastic elastomer modified with polar groups.

In a further aspect, the present invention relates to the use of a non-polar

thermoplastic elastomer modified with polar groups in at least one layer (B) of a multi-layered article for improving adhesion of the at least two layers (A) and (B) in adherent contact with each other, wherein

The multi-layered article of the present invention surprisingly shows good adhesion between the layers (A) and (B) without need of an additional tie layer. Further, the multi-layered article shows good mechanical properties in tensile properties and impact properties, good transparency and high surface tension.

The multi-layered article according to the invention thus qualifies for new applications such as anti-dripping greenhouse films, but also as a replacement of five layer structures to three layer structures in applications such as biaxially oriented films, blown films, cast films, molding applications or thermoforming applications.

Definitions

In adherent contact means that the layers (A) and (B) and optionally layer (C) are in direct contact with each other without the presence of an additional tie layer between the layers.

A tie layer is a polymer layer introduced for the purpose of improving adhesion between two polymer layers that would otherwise experience poor adhesion. A tie layer has good adhesion to the layers with which it is in adherent contact, whilst said layers would experience poor adhesion, were they in adherent contact with each other, as defined above (i.e. in the absence of a tie layer).

A random copolymer is a copolymer of monomer units and comonomer units in which the comonomer units are distributed randomly over the polymeric chain.

A block copolymer is a copolymer of different monomer units X and Y in which the different monomer units cluster together and from so-called“blocks” of repeating units of -X-X-X-X- and -Y-Y-Y-Y- blocks which blocks alternate in the polymeric chain.

A homopolymer is a polymer which essentially consists of one sort of monomer units. Due to impurities especially during commercial polymerization processes a homopolymer can comprise up to 0.1 mol% comonomer units, preferably up to 0.05 mol% comonomer units and most preferably up to 0.01 mol% comonomer units. An ethylene based polymer is a polymer with a weight majority of ethylene monomer units, i.e. more than 50 wt% of ethylene monomer units.

A propylene based polymer is a polymer with a weight majority of propylene monomer units, i.e. more than 50 wt% of propylene monomer units.

A heterophasic polypropylene is a propylene-based copolymer with a crystalline matrix phase, which can be a propylene homopolymer or a random copolymer of propylene and at least one alpha-olefin comonomer, and an elastomeric phase dispersed therein. The elastomeric phase can be a propylene copolymer with a high amount of comonomer which is not randomly distributed in the polymer chain but are distributed in a comonomer-rich block structure and a propylene-rich block structure.

A heterophasic polypropylene usually differentiates from a one-phasic propylene copolymer in that it shows two distinct glass transition temperatures Tg which are attributed to the matrix phase and the elastomeric phase.

A thermoplastic elastomer is a class of copolymers, which consists of materials with both thermoplastic and elastomeric properties. At lower temperatures, like room temperature, these materials show elastomeric behaviour whereas when heated these materials show thermoplastic behaviour.

Non-polar thermoplastic elastomers are thermoplastic elastomers, which before modification only include non-polar monomers. In the following amounts are given in % by weight (wt%) unless it is stated otherwise.

Figures

Figure 1 shows a cross-sectional microscope image of the three-layer blown film of example IE2 Figure 2 shows a cross-sectional microscope image of the three-layer blown film of example IE1

Figure 3 shows a cross-sectional microscope image of the three-layer blown film of example CE2

Figure 4 shows a cross-sectional microscope image of the three-layer coextrusion molded cup prepared according to the Klear Can concept

Figure 5 shows a microscope image of the inner side of the three-layer coextrusion molded cup prepared according to the Klear Can concept

Figure 6 shows an angular cross-sectional microscope image of the three-layer coextrusion molded cup prepared according to the Klear Can concept

Detailed Description

General

In addition to the polymers the polymer compositions of all layers of the multi- layered article may also comprise, and preferably comprise, additives, such as antioxidants, process stabilisers, antiblock agents, lubricants, acid scavengers, pigments and the like.

Antioxidants and stabilisers are used for stabilising the polymer against oxidation. The group of antioxidants includes sterically hindered phenols (phenolic AO);

phosphites and phosphonites; sulphur containing AO; alkyl radical scavengers;

aromatic amines; hindered amine stabilisers (mainly known as UV-stabilisers), HAS; and combinations of two or more of the above-mentioned substances.

Sterically hindered phenols are added to give long term stability in finished product. This is measured by performing oven ageing test, which is an accelerated test, and from this lifetime is calculated at the use temperature (so called Arrhenius plot). In addition phenols contribute to process-stability. In some occasions only a phenol is added as the stabiliser but this is not common.

Phosphites and phosphonites give protection during processing. They react with hydroperoxides to prevent chain scission or combination from taking place. They are not very efficient alone and normally they are used in blends with phenolic AO. This so called synergistic blend gives a good processing stabilisation.

Antiblocking and slip agents may be used for improving the handling properties of the film.

Slip agents migrate to the surface and act as lubricants polymer to polymer and polymer against metal rollers, giving reduced coefficient of friction (CoF) as a result. Antiblocking agents are added to cause a slight surface roughness that prevents the film sticking to itself.

Both erucamide and oleamide are used as slip agents. Oleamide may be quicker at the surface due to lower Mw, but when equilibrium is reached erucamide normally give slightly better slip-effect at same concentration.

Different minerals, such as talc, natural silica and synthetic silica, are used as antiblocking agents for films.

Acid scavengers are used for deactivating acidic impurities. Most of the polyolefins contain small level of chlorine due to the catalyst residues (in the magnitude 10-20 ppm). Acid scavengers are added to protect the processing equipment against corrosion caused by hydrochloric acid. The main product used is Ca-stearate.

Lubricants may be used for several purposes, e.g. to improve output, to eliminate melt fracture, to give higher gloss, go give“internal lubrication”, etc. In addition acid scavengers may be added in surplus to give lubrication.

Different pigments may be used if a certain colour is required. The pigments are well known in the industry and the pigment is selected based on the desired colour. For instance, titanium oxide may be used for white colour, carbon black for black colour and ultramarine blue for blue colour. The pigments are typically added as

masterbatches.

The amount of additives in the polymer compositions of all layers of the multi layered article is usually not higher than 10 wt%, preferably from 0 to 10 wt%, more preferably from 0.001 to 5.0 wt%, still more preferably from 0.005 to 2.0 wt% and most preferably from 0.01 to 1.0 wt%. Layer (B)

The multi-layered article comprises a layer (B) which comprises a polymer composition (PC-B) which comprises a polyolefin and from 1.0 to 15.0 wt% of a non-polar thermoplastic elastomer modified with polar groups.

Preferably the polymer composition (PC-B) essentially consists of the polyolefin and the non-polar thermoplastic elastomer modified with polar groups.

By“essentially consists of’ is meant that the layer may contain minor amount of additives as discussed above.

Typically the layer (B) then comprises from 80 to 99 wt%, preferably from 83 to 95 wt% and more preferably at least 85 to 90 wt% of the polyolefin.

Preferably, the layer (B) comprises from 2.5 to 13.0 wt%, more preferably from 5.0 to 12.0 wt% and most preferably from 7.5 to 11.0 wt% of the non-polar

thermoplastic elastomer modified with polar groups. The non-polar thermoplastic elastomer modified with polar groups preferably is a styrene block copolymer.

It is preferred that the styrene block copolymer is a block copolymer comprising styrene polymer units and ethylene-based polymer units. More preferably the styrene block copolymer is a block copolymer comprising styrene polymer units and ethylene copolymer units comprising ethylene monomer units and alpha-olefin comonomer units having from 3 to 12 carbon atoms, such as propylene, 1 -butene, 1- hexene and l-octene, more preferably 1 -butene and 1 -hexene and most preferably 1- butene.

Thus, it is especially preferred that the styrene block copolymer is a block copolymer comprising styrene polymer units and ethylene/ 1 -butene copolymer units.

It is preferred that the styrene block copolymer is a linear block copolymer. Mostly preferred the styrene block copolymer is a linear triblock copolymer based on styrene polymer units and ethylene/ 1 -butene copolymer units. Such styrene block copolymers are commercially available e.g. from Kraton Corporation. The amount of styrene polymer units in the styrene block copolymer is preferably in the range of from 10 to 50 wt%, more preferably of from 20 to 40 wt%.

The non-polar thermoplastic elastomer is preferably modified with organic acid derivatives such as organic acid anhydrides and organic acid esters, preferably organic acid anhydrides.

It is especially preferred that the non-polar thermoplastic elastomer is modified with maleic anhydride units. The non-polar thermoplastic elastomer is preferably modified with maleic anhydride units by grafting the maleic anhydride units onto the polymeric backbone of the non-polar thermoplastic elastomer.

Preferably, the non-polar thermoplastic elastomer modified with polar groups comprises from 0.1 to 5.0 wt%, more preferably from 0.2 to 4.0 wt%, still more preferably from 0.5 to 3.0 wt% and most preferably from 1.0 to 2.5 wt% of polar groups.

It is especially preferred that the non-polar thermoplastic elastomer modified with polar groups is a block copolymer of styrene polymer units and ethylene/ 1 -butene random copolymer units grafted with from 0.1 to 5.0 wt%, preferably from 0.2 to 4.0 wt%, more preferably from 0.5 to 3.0 wt% and most preferably from 1.0 to 2.5 wt% maleic anhydride units.

One especially preferred commercially available styrene block copolymer modified with maleic anhydride units is commercially available from Kraton Corporation as Kraton™ FG1901 GT. The polyolefin in polymer composition (PC-B) is suitably selected from ethylene based polymers and propylene based polymers.

The ethylene based polymers are preferably selected from homopolymers or copolymers of ethylene, such as high density polyethylene, medium density polyethylene, linear low density polyethylene, ethylene-based plastomers, ethylene- based elastomers, low density polyethylene, blends thereof and the like.

Especially preferred the ethylene based polymer is a linear low density polyethylene (LLDPE) or a high density polyethylene (HDPE).

The LLDPE may have a density in the range of 910 to 950 kg/m³, preferably 920 to 945 kg/m3, such as 930 to 940 kg/m3.

MFR2 (l90°C, 2.16 kg, ISO 1133) of suitable LLDPE's is in the range of from 0.01 to 20 g/lO min, preferably in the range of 0.05 to 10 g/lO min, more preferably of from 0.1 to 6.0 g/lO min and even more preferably of from 0.1 to 5.0 g/lO min.

The weight average molecular weight Mw of the LLDPE is preferably in the range of 100 000 to 200 000 g/mol.

The Mw/Mn of the LLDPE can be in a quite broad range. Preferred Mw/Mn values are 3 or more, such as 6 or more, even 10 or more. Ranges of 3.5 to 30 are envisaged.

The LLDPE contains at least one or two comonomer(s). Suitable comonomers are C3-C10 alpha-olefin comonomers. Thus the LLDPE can be a copolymer of ethylene and one C3-C10 alpha-olefin comonomer or a terpolymer of ethylene and two different C3-C10 alpha-olefin comonomers.

Preferably the comonomers are selected from the group of 1 -butene, 1 -hexene and 1- octene. It is preferred if the comonomer employed is 1 -butene and/or 1 -hexene. Preferred terpolymers comprise 1 -butene and 1 -hexene comonomers.

The overall comonomer content in the total polymer is 0.3 to 7.0 % by mol, preferably 0.6 to 4.5 % by mol, more preferably 1.0 to 3.5 % by mol and most preferably 1.2 to 2.3 % by mol. If the LLDPE is a terpolymer of ethylene and two different C3-C10 alpha-olefin comonomers, preferably 1 -butene and 1 -hexene, 1 -butene is present in an amount of 0.1 to 3.0 % by mol, preferably 0.2 to 2.0 % by mol, more preferably 0.3 to 1.5 % by mol and most preferably 0.4 to 0.8 % by mol and hexene is present in an amount of 0.2 to 4.0 % by mol, preferably 0.4 to 2.5 % by mol, more preferably 0.7 to 2.0 % by mol and most preferably 0.8 to 1.5 % by mol.

The LLDPE can be unimodal or multimodal, preferably multimodal. A unimodal LLDPE possesses a single peak in its GPC spectrum as it is made in a single stage process. It is most preferred if the LLDPE is a multimodal LLDPE formed from a homopolymer component and a copolymer component. These polymers are well known in the art and are available from Borouge or Borealis and others, such as grades under trade names Borshape™ and Borstar™.

Preferably such multimodal, like bimodal LLDPEs are produced in a multi-stage polymerization using the same catalyst. Thus, two slurry reactors or two gas phase reactors could be employed. Preferably however, such multimodal, like bimodal

LLDPEs are made using a slurry polymerization in a loop reactor followed by a gas phase polymerization in a gas phase reactor.

The LLDPE suitable for the invention can be produced using Ziegler Natta catalysis or single site catalysis (mLLDPE), but is preferably produced using a Ziegler Natta catalyst. Such catalysts are well known in the art.

Suitable LLDPE resins and their production are disclosed, among others in WO-A- 2004/000933, EP-A-1378528, WO-A-2004/011517, EP-A-2067799 and WO-A- 2007/003322. Suitable HDPE has a density within the range of 940 up to 980 kg/m³, preferably of about 945 kg/m³ to about 965 kg/m³. More preferably, the density is within the range of about 950 kg/m³ to about 965 kg/m³.

Preferably the HDPE is a unimodal HDPE.

HDPEs can be homopolymers or copolymers with at least one alpha-olefin having from 3 to 10 carbon atoms. The melt flow rate (MFR) of the HDPE is not critical and can be varied depending on the mechanical properties desired for an end application.

In one preferable embodiment MFR₂ value in the range of from 0.05 to 10 g/lO min, preferably from 0.1 to 7.0 g/lO min, more preferably from 0.2 to 5.0 g/lO min, yet more preferably from 0.3 to 3.0 g/lO min, even more preferably from 0.4 to 2.0 g/lO min and most preferably from 0.5 to 1.3 g/lO min are desired.

The molecular weight distribution (MWD) expressed as Mw/Mn of the HDPE can be in a broad range. MWD is preferably in the range from 2 to 20, preferably 2.5 to 15, more preferably 3 to 10 and most preferably 3.5 to 7.

The HDPE may be a known and e.g. commercially available, polyethylene polymer or said HDPE polymer may be prepared using any coordination catalyst, typically ZN catalysts, Cr-catalyst as well as single site catalysts (SSC) in well-documented polymerization processes.

Suitable films, HDPE resins and their production are disclosed, among others in WO-A- 1999/058584, WO-A- 1999/051649, WO-A-2007/104513 and WO-A-

2007/065644.

The propylene based polymer are preferably selected from homopolymers or copolymers of propylene, such as propylene homopolymers, propylene random copolymers or heterophasic propylene copolymers. Especially preferred are propylene homopolymers or propylene random copolymers

The melt flow rate (MFR₂) of the propylene based polymer is preferably 0.5-20 g/lO min, more preferably 1-20 g/lO min.

In case the propylene based polymer is a propylene random copolymer, one or more, e.g. two, three, or more comonomers may be present. Therefore, the term copolymer used herein includes terpolymers and also copolymers based on more than three different polymerizable monomers. The comonomer of propylene random copolymer is preferably selected from ethylene, C_4-C₈-a-olefms and mixtures thereof, suitably from ethylene, butene, hexene and/or octene.

The comonomer content in propylene random copolymer is preferably less than 7.5 mol.-% based on the propylene random copolymer. The comonomer content will be usually at least 0.5 mol.-% based on the propylene random copolymer.

In the case that the propylene based polymer is a propylene homopolymer the propylene homopolymer preferably has a pentad isotacticity (mmmm) of equal or more than 95.0 mol%, more preferably of equal to or more than 98.mol%. The pentad isotacticity (mmmm) will be necessarily equal or below 100.0 mol.-% and will be usually equal or below 99.8 mol.-%.

It is further preferred that the propylene homopolymer has a melting temperature (T_m) of at least 150.0 °C more preferably of at least l53°C. The upper limit of the melting temperature is usually equal or below 175 °C.

The propylene homopolymer preferably has a xylene cold soluble (XCS) content of equal or below 1.5 wt.-%.

The propylene homo- or copolymer can be commercially available product or can be produced e.g. by conventional polymerization processes and process conditions using e.g. the conventional catalyst system, like Ziegler-Natta catalyst or single site catalyst, including metallocene catalyst, preferably Ziegler-Natta catalyst, which have a well-known meaning and which are well described in the literature. The propylene homo- or copolymer, of the invention may for instance be produced in a continuous multistage process in a conventional manner. Such process preferably comprises at least two polymerization stages. A preferred multistage process is a “loop-gas phase”-process, such as developed by Borealis (known as BORSTAR® technology) described e.g. in patent literature, such as in EP 0 887 379, WO 92/12182 WO 2004/000899, WO 2004/111095, WO 99/24478, WO 99/24479 or in WO 00/68315.

The polymer composition (PC-B) may contain small amount of additives and other polymers. However, the amount of polymers different from the polyolefin and the non-polar thermoplastic elastomer modified with polar groups is typically not more than 10 wt%, preferably not more than 5 wt% and especially preferably not more than 2 wt%, such as not more than 1 wt%.

Layer (A)

The multi-layered article comprises a layer (A) which comprises a polymer composition (PC- A) which comprises a copolymer of ethylene and vinyl alcohol. Preferably the polymer composition (PC-A) essentially consists of the copolymer of ethylene and vinyl alcohol. By“essentially consists of’ is meant that the layer may contain minor amount of additives known in the art, such as antioxidants, and other polymers as long as such other polymers do not adversely influence the oxygen barrier properties of the copolymer of ethylene and vinyl alcohol. Typically the layer then comprises at least 95 % by weight, preferably at least 98 % by weight and more preferably at least 99 % by weight of the copolymer of ethylene and vinyl alcohol. In another embodiment, the polymer composition (PC-A) further comprises a non polar thermoplastic elastomer is modified with maleic anhydride units.

The non-polar thermoplastic elastomer modified with polar groups preferably is a styrene block copolymer. It is preferred that the styrene block copolymer is a block copolymer comprising styrene polymer units and ethylene-based polymer units. More preferably the styrene block copolymer is a block copolymer comprising styrene polymer units and ethylene copolymer units comprising ethylene monomer units and alpha-olefin comonomer units having from 3 to 12 carbon atoms, such as propylene, 1 -butene, 1- hexene and l-octene, more preferably 1 -butene and 1 -hexene and most preferably 1- butene.

It is preferred that the styrene block copolymer is a linear block copolymer.

Mostly preferred the styrene block copolymer is a linear triblock copolymer based on styrene polymer units and ethylene/ 1 -butene copolymer units. Such styrene block copolymers are commercially available e.g. from Kraton Corporation.

The amount of styrene polymer units in the styrene block copolymer is preferably in the range of from 10 to 50 wt%, more preferably of from 20 to 40 wt%.

One especially preferred commercially available styrene block copolymer modified with maleic anhydride units is commercially available from Kraton Corporation as Kraton™ FG1901 GT.

The amount of non-polar thermoplastic elastomer modified with polar groups in the polymer composition (PC-A) is preferably selected as to improve the adhesion of layer (A) to layer (B) and/or optional layer (D) but at the same time not to impair the oxygen barrier properties of layer (A). Preferably, the amount of non-polar thermoplastic elastomer modified with polar groups in the polymer composition (PC- A) is preferably selected in the range of from 0.5 to 10.0 wt%, more preferably of from 1.5 to 9.0 wt% and most preferably of from 2.0 to 8.0 wt%. In addition to an optional small amount of additives as described above the rest of the weight amount of the polymer composition (PC-A) of said embodiment is preferably made from the copolymer of ethylene and vinyl alcohol.

Suitably the copolymer of ethylene and vinyl alcohol has a content of ethylene units of from 20 to 45 % by mole, preferably from 25 to 40 % by mole and more preferably from 27 to 37 % by mole.

Furthermore, the copolymer of ethylene and vinyl alcohol suitably has a density of from 1000 to 1250 kg/m³, preferably from 1050 to 1230 kg/m³ and more preferably from 1100 to 1220 kg/m³.

It furthermore suitably has a melt flow rate MFR₂ (measured under a load of 2.16 kg at a temperature of 190 °C) of from 1 to 10 g/lO min, preferably from 2 to 8 g/lO min and more preferably from 2.5 to 7.5 g/lO min.

The layer (A) suitably has a basis weight of from 1 to 10 g/m², preferably from 1 to 8 g/m² and more preferably from 2 to 6 g/m². A too low basis weight may lead to insufficient barrier properties. A too high basis weight leads to an unnecessary high cost of the structure and may also make the coating thicker than desired.

Furthermore, the recyclability may suffer if the multi-layered article contains too much of the copolymer of ethylene and vinyl alcohol.

Optional layer (C)

The multi-layered article can optionally comprise a layer (C) which is in adherent contact with layer (B).

Layer (C) preferably comprises a polymer composition (PC-C) which comprises a copolymer of ethylene and vinyl alcohol.

Preferably the polymer composition (PC-C) essentially consists of the copolymer of ethylene and vinyl alcohol. By“essentially consists of’ is meant that the layer may contain minor amount of additives known in the art, such as antioxidants, and other polymers as long as such other polymers do not adversely influence the oxygen barrier properties of the copolymer of ethylene and vinyl alcohol. Typically the layer then comprises at least 95 % by weight, preferably at least 98 % by weight and more preferably at least 99 % by weight of the copolymer of ethylene and vinyl alcohol.

In another embodiment, the polymer composition (PC-C) further comprises a non- polar thermoplastic elastomer modified with polar groups.

The non-polar thermoplastic elastomer modified with polar groups preferably is a styrene block copolymer.

It is preferred that the styrene block copolymer is a block copolymer comprising styrene polymer units and ethylene-based polymer units. More preferably the styrene block copolymer is a block copolymer comprising styrene polymer units and ethylene copolymer units comprising ethylene monomer units and alpha-olefin comonomer units having from 3 to 12 carbon atoms, such as propylene, 1 -butene, 1- hexene and l-octene, more preferably 1 -butene and 1 -hexene and most preferably 1- butene. Thus, it is especially preferred that the styrene block copolymer is a block copolymer comprising styrene polymer units and ethylene/ 1 -butene copolymer units.

It is preferred that the styrene block copolymer is a linear block copolymer. The amount of styrene polymer units in the styrene block copolymer is preferably in the range of from 10 to 50 wt%, more preferably of from 20 to 40 wt%.

It is especially preferred that the non-polar thermoplastic elastomer is modified with maleic anhydride units. The non-polar thermoplastic elastomer is preferably modified with maleic anhydride units by grafting the maleic anhydride units onto the polymeric backbone of the non-polar thermoplastic elastomer. Preferably, the non-polar thermoplastic elastomer modified with polar groups comprises from 0.1 to 5.0 wt%, more preferably from 0.2 to 4.0 wt%, still more preferably from 0.5 to 3.0 wt% and most preferably from 1.0 to 2.5 wt% of polar groups. It is especially preferred that the non-polar thermoplastic elastomer modified with polar groups is a block copolymer of styrene polymer units and ethylene/ 1 -butene random copolymer units grafted with from 0.1 to 5.0 wt%, preferably from 0.2 to 4.0 wt%, more preferably from 0.5 to 3.0 wt% and most preferably from 1.0 to 2.5 wt% maleic anhydride units. One especially preferred commercially available styrene block copolymer modified with maleic anhydride units is commercially available from Kraton Corporation as Kraton™ FG1901 GT. The amount of non-polar thermoplastic elastomer modified with polar groups in the polymer composition (PC-C) is preferably selected as to improve the adhesion of layer (C) to layer (B) but at the same time not to impair the oxygen barrier properties of layer (C). Preferably, the amount of non-polar thermoplastic elastomer modified with polar groups in the polymer composition (PC-C) is preferably selected in the range of from 0.5 to 10.0 wt%, more preferably of from 1.5 to 9.0 wt% and most preferably of from 2.0 to 8.0 wt%. In addition to an optional small amount of additives as described above the rest of the weight amount of the polymer composition (PC-C) of said embodiment is preferably made from the copolymer of ethylene and vinyl alcohol.

The layer (C) suitably has a basis weight of from 1 to 10 g/m², preferably from 1 to 8 g/m² and more preferably from 2 to 6 g/m². A too low basis weight may lead to insufficient barrier properties. A too high basis weight leads to an unnecessary high cost of the structure and may also make the coating thicker than desired.

Furthermore, the recyclability may suffer if the multi-layered article contains too much of the copolymer of ethylene and vinyl alcohol. In a preferred embodiment optional layer (C) comprises the same polymer composition including the same components as the polymer composition (PC-A) of layer (A). In said embodiment, layer (C) preferably is the same as layer (A).

Optional layer (D)

The multi-layered article can optionally comprise a layer (D) which is in adherent contact with layer (A).

Optional layer (D) preferably comprises a polymer composition (PC-D) which comprises a polyolefin and from 1.0 to 15.0 wt% of a non-polar thermoplastic elastomer modified with polar groups.

Preferably the polymer composition (PC-D) essentially consists of the polyolefin and the non-polar thermoplastic elastomer modified with polar groups.

Typically the layer (D) then comprises from 80 to 99 wt%, preferably from 83 to 95 wt% and more preferably at least 85 to 90 wt% of the polyolefin.

Preferably, the layer (D) comprises from 2.5 to 13.0 wt%, more preferably from 5.0 to 12.0 wt% and most preferably from 7.5 to 11.0 wt% of the non-polar

thermoplastic elastomer modified with polar groups.

It is preferred that the styrene block copolymer is a linear block copolymer.

The polyolefin in polymer composition (PC-D) is suitably selected from ethylene based polymers and propylene based polymers.

The overall comonomer content in the total polymer is 0.3 to 7.0 % by mol, preferably 0.6 to 4.5 % by mol, more preferably 1.0 to 3.5 % by mol and most preferably 1.2 to 2.3 % by mol.

If the LLDPE is a terpolymer of ethylene and two different C3-C10 alpha-olefin comonomers, preferably 1 -butene and 1 -hexene, 1 -butene is present in an amount of

0.1 to 3.0 % by mol, preferably 0.2 to 2.0 % by mol, more preferably 0.3 to 1.5 % by mol and most preferably 0.4 to 0.8 % by mol and hexene is present in an amount of 0.2 to 4.0 % by mol, preferably 0.4 to 2.5 % by mol, more preferably 0.7 to 2.0 % by mol and most preferably 0.8 to 1.5 % by mol.

Preferably such multimodal, like bimodal LLDPEs are produced in a multi-stage polymerization using the same catalyst. Thus, two slurry reactors or two gas phase reactors could be employed. Preferably however, such multimodal, like bimodal LLDPEs are made using a slurry polymerization in a loop reactor followed by a gas phase polymerization in a gas phase reactor.

The LLDPE suitable for the invention can be produced using Ziegler Natta catalysis or single site catalysis (mLLDPE), but is preferably produced using a Ziegler Natta catalyst. Such catalysts are well known in the art. Suitable LLDPE resins and their production are disclosed, among others in WO-A- 2004/000933, EP-A-1378528, WO-A-2004/011517, EP-A-2067799 and WO-A- 2007/003322. Suitable HDPE has a density within the range of 940 up to 980 kg/m³, preferably of about 945 kg/m³ to about 965 kg/m³. More preferably, the density is within the range of about 950 kg/m³ to about 965 kg/m³.

Preferably the HDPE is a unimodal HDPE.

HDPEs can be homopolymers or copolymers with at least one alpha-olefin having from 3 to 10 carbon atoms.

The melt flow rate (MFR) of the HDPE is not critical and can be varied depending on the mechanical properties desired for an end application.

2007/065644.

In case the propylene based polymer is a propylene random copolymer, one or more, e.g. two, three, or more comonomers may be present. Therefore, the term copolymer used herein includes terpolymers and also copolymers based on more than three different polymerizable monomers.

The comonomer of propylene random copolymer is preferably selected from ethylene, C_4-C₈-a-olefins and mixtures thereof, suitably from ethylene, butene, hexene and/or octene.

The propylene homo- or copolymer can be commercially available product or can be produced e.g. by conventional polymerization processes and process conditions using e.g. the conventional catalyst system, like Ziegler-Natta catalyst or single site catalyst, including metallocene catalyst, preferably Ziegler-Natta catalyst, which have a well-known meaning and which are well described in the literature.

The propylene homo- or copolymer, of the invention may for instance be produced in a continuous multistage process in a conventional manner. Such process preferably comprises at least two polymerization stages. A preferred multistage process is a “loop-gas phase”-process, such as developed by Borealis (known as BORSTAR® technology) described e.g. in patent literature, such as in EP 0 887 379, WO

92/12182 WO 2004/000899, WO 2004/111095, WO 99/24478, WO 99/24479 or in WO 00/68315.

The polymer composition (PC-D) may contain small amount of additives and other polymers. However, the amount of polymers different from the polyolefin and the non-polar thermoplastic elastomer modified with polar groups is typically not more than 10 wt%, preferably not more than 5 wt% and especially preferably not more than 2 wt%, such as not more than 1 wt%.

In a preferred embodiment optional layer (D) comprises the same polymer composition including the same components as the polymer composition (PC-B) of layer (B). In said embodiment, layer (D) preferably is the same as layer (B).

Multi-layered article

The multi-layered article according to the present invention comprises layers (A) and (B) as defined above or below in adherent contact with each other. In one preferred embodiment the multi-layered article comprises at least two layers (A) and (B) in adherent contact with each other, wherein

layer (B) comprises a polymer composition (PC-B) comprising a polyolefin selected from the group of homo- or copolymer of propylene, LLDPE or HDPE, and from 2.5 to 13.0 wt% of a non-polar thermoplastic elastomer modified with organic acid derivatives.

The multi-layered article may comprise further layers which are different from layers (A) and (B) with the proviso that none of the further layers is a tie layer.

The multi-layered article is preferably free from tie layers.

The multi-layered article according to present invention preferably is a three layer article with a core layer which is sandwiched by two outer layers.

In one embodiment, the multi-layered article further comprises layer (C) as defined above or below. In said embodiment layer (C) is in adherent contact with layer (B). Preferably the multi-layered article of said embodiment is a three-layered film with the layer structure (A)-(B)-(C). In said embodiment layer (B) is the core layer and layers (A) and (C) are the outer layers.

It is especially preferred in said embodiment that layer (C) has the same polymer composition as polymer composition (PC-A). Thus, it is especially preferred that the multi-layered article of said embodiment is a three-layered film with the layer structure (A)-(B)-(C=A).

In another embodiment, the multi-layered article further comprises layer (D) as defined above or below. In said embodiment layer (D) is in adherent contact with layer (A).

Preferably the multi-layered article of said embodiment is a three-layered film with the layer structure (B)-(A)-(D). In said embodiment layer (A) is the core layer and layers (B) and (D) are the outer layers.

It is especially preferred in said embodiment that layer (D) has the same polymer composition as polymer composition (PC-B). Thus, it is especially preferred that the multi-layered article of said embodiment is a three-layered film with the layer structure (B)-(A)-(D=B).

The multi-layered article also can comprise further layers in addition to layers (A) and (B) and optional layers (C) and/or (D).

These layers are typically selected from layers comprising polyolefin based compositions such as polyethylene based compositions or polypropylene based compositions and/or compositions based on copolymers of ethylene and vinyl alcohol.

The multi-layered article according to the present invention preferably is a multi layered blown film, a multi-layered cast film, a multi-layered biaxially oriented film, a multi-layered molded article or a multi-layered thermoformed article such as molded or thermoformed cups, cans, bottles or other three-dimensional structures suitable for packaging.

Further the multi-layered article according to the present invention, especially of the structure (B)-(A)-(D), can be used as anti-dripping greenhouse film.

The total cross-sectional thickness over all layers of the multi-layered article is preferably in the range of from 20 pm to 500 pm, more preferably of from 30 pm to 200 pm.

Thereby, in case of a three layer article the core layer preferably has a thickness of from 10 pm to 400 pm, more preferably of from 20 pm to 150 pm.

The outer layers thereby preferably have a thickness of from 5 pm to 50 pm, more preferably of from 5 pm to 25 pm.

The multi-layered article preferably has a tensile modulus both in machine direction (TM-MD) and in traverse direction (TM-TD) of at least 750 MPa, more preferably of at least 850 MPa. Suitably, the upper limit of the tensile modulus both in machine direction (TM-MD) and in traverse direction (TM-TD) does not exceed 2000 MPa. It is preferred that the tensile modulus in machine direction (TM-MD) and in traverse direction (TM-TD) do not differ more than 30%, more preferably no more than 20%.

The multi-layered article preferably has a dart drop impact strength (DDI) of at least 200 g, more preferably of at least 220 g, measured on a film having a cross-sectional thickness of 50 pm. Suitably, the upper limit of the dart drop impact strength does not exceed 500 g.

The multi-layered article, especially of the structure (A)-(B)-(C), preferably has a surface tension on both surfaces of at least 30 rhN/m, more preferably of at least 40 mN/m. Suitably, the upper limit of the surface tension does not exceed 100 rhN/m.

Preparation of the multi-layered article

The multi-layered article according to the present invention is preferably prepared by co-extruding the different layers of the article and then further preparing a cast film, blown film, molding or thermoforming.

Description of film production by blown film technology

The above described multi-layered articles can be blown films such as water or air quench blown films, preferably air quenched blown films.

In principle the process comprising the steps of

(i) blowing up a tube of the coextruded molten material with air perpendicularly to the upwards direction from a side-fed blown film die;

(ii) cooling it down with water contact cooling ring or air quench;

(iii) folding it and guiding it over deflector rolls onto the winder.

In the blown film process the polymer melts are coextruded through two or more, such as three, annular die(s) and blown into a tubular multi-layered film by forming a bubble which is collapsed between nip rollers after solidification. The blown extrusion can be preferably effected at a temperature in the range l60°C to 240°C, and cooled by water or preferably by blowing gas (generally air) at a temperature of lO°C to 50°C to provide a frost line height of 0.5 to 8 times the diameter of the die. The blow up ratio should generally be in the range of from 1.5 to 4, such as from 2 to 4, preferably 2.5 to 3.5. Description of film production by cast film technology

In this most simple technology for producing polymer films, the polymer melts are coextruded through two or more, such as three, slot die(s) fed by a (normally single- screw) extruder onto a first cooled roll, the so-called chill-roll. From this roll, the already solidified film is taken up by a second roll (nip roll or take-up roll) and transported to a winding device after trimming the edges. Only a very limited amount of orientation is created in the film, which is determined by the ratio between die thickness and film thickness or the extrusion speed and the take-up speed, respectively.

Due to its technical simplicity, cast film technology is a very economical and easy- to-handle process. The films resulting from this technology are characterised by good transparency and rather isotropic mechanical properties (limited stiffness, high toughness).

In case a film is produced by cast film technology the molten polymer compositions are coextruded through two or more, such as three, slot extrusion dies onto a chill roll to cool the compositions to a solid multi-layered film. Typically the polymer compositions are firstly compressed and liquefied in an extruder, it being possible for any additives to be already added to the polymer compositions or introduced at this stage via a masterbatch. The melt is then forced through the flat-film dies(slot dies), and the extruded film is taken off on one or more take-off rolls, during which it cools and solidifies. It has proven particularly favorable to keep the take-off roll or rolls, by means of which the extruded film is cooled and solidified, at a temperature from l0°C to 50°C, preferably from l5°C to 40°C. Description ofbiaxially oriented film production For the preparation of biaxially oriented multilayered films, two main technologies are used for this process, which are described in detail in A. Ajji & M. M. Dumoulin, Biaxially oriented polypropylene (BOPP) process, in: J. Karger-Kocsis (Ed.) Polypropylene: An A-Z Reference, Kluwer, Dordrecht 1999, 60-67. Orientation and properties are determined by the draw ratio and details of the process; the films have generally the highest crystallinity and stiffness achievable.

The layers of the multi-layered article of the present invention can further be coextruded and then subjected to injection molding or injection stretch blow molding or thermo forming as known in the art to produce a molded or thermo formed articles.

Extruding devices suitable for the present process are discontinuous and continuous kneaders, twin screw extruders and single screw extruders with special mixing sections and co -kneaders.

Use

The present invention further relates to the use of a non-polar thermoplastic elastomer modified with polar groups in at least one layer (B) of a multi-layered article for improving adhesion of the at least two layers (A) and (B) in adherent contact with each other, wherein

Thereby it is preferred that the multi-layered article, layers (A) and (B), the polymer compositions (PC-A) and (PC-B), the ethylene-vinyl alcohol copolymer, the polyolefin and the non-polar thermoplastic elastomer modified with polar groups are as defined above or below. Benefits of the invention

The multi-layered article according to the invention preferably has a high

transparency, and good optical properties and good surface properties.

Further, the layers of the multi-layered article show good adhesion to each other so that little to no delamination can be observed.

The multi-layered article further shows good mechanical properties in regard of a stiffness to impact properties balance.

Still further, the multi-layered article, especially of the structure (A)-(B)-(C), shows a high surface tension.

Thereby, the presence of tie layers can be omitted in the multi-layered article according to the invention.

Examples:

1. Measurement methods

a) Melt Flow Rate (MFR₂)

The melt flow rate is the quantity of polymer in grams which the test apparatus standardized to ISO 1133 extrudes within 10 minutes at a certain temperature under a certain load.

The melt flow rate MFR₂ of a propylene-based polymer and a styrene block copolymer is usually measured at 230°C with a load of 2.16 kg (MFR230/2.16) according to ISO 1133.

The melt flow rate MFR₂ of ethylene-based polymer and an ethylene-vinyl alcohol copolymer is usually measured at l90°C with a load of 2.16 kg (MFR190/2.16) according to ISO 1133.

The melt flow rate MFRs of a propylene-based polymer and a styrene block copolymer is usually measured at 230°C with a load of 5 kg (MFR230/5) according to ISO 1133. The melt flow rate MFR₅ of ethylene-based polymer and an ethylene-vinyl alcohol copolymer is usually measured at l90°C with a load of 5 kg (MFR190/5) according to ISO 1133. b) Density

The density is measured according to ISO 1183D. The samples preparation is carried out by compression moulding according to ISO 1872-2:2007. c) Comonomer content

Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used to quantify the comonomer content of the polymers.

Comonomer content quantification of poly(propylene-co-ethylene) copolymers

Quantitative '¾{¾} NMR spectra were recorded in the solution- state using a Bruker Advance III 400 NMR spectrometer operating at 400.15 and 100.62 MHz for ¹ H and ¹³C respectively. All spectra were recorded using a ¹³C optimised 10 mm extended temperature probe head at l25°C using nitrogen gas for all pneumatics. Approximately 200 mg of material was dissolved in 3 ml of /,2-tctrachlorocthanc-i/ (TCE-i/ ) along with chromium-(III)-acetylacetonate (Cr(acac)₃) resulting in a 65 mM solution of relaxation agent in solvent {8} . To ensure a homogenous solution, after initial sample preparation in a heat block, the NMR tube was further heated in a rotatory oven for at least 1 hour. Upon insertion into the magnet the tube was spun at 10 Hz. This setup was chosen primarily for the high resolution and quantitatively needed for accurate ethylene content quantification. Standard single-pulse excitation was employed without NOE, using an optimised tip angle, 1 s recycle delay and a bi level WALTZ16 decoupling scheme {3, 4}. A total of 6144 (6k) transients were acquired per spectra.

Quantitative '¾{¾} NMR spectra were processed, integrated and relevant quantitative properties determined from the integrals using proprietary computer programs. All chemical shifts were indirectly referenced to the central methylene group of the ethylene block (EEE) at 30.00 ppm using the chemical shift of the solvent. This approach allowed comparable referencing even when this structural unit was not present. Characteristic signals corresponding to the incorporation of ethylene were observed {7}.

The comonomer fraction was quantified using the method of Wang et. al. {6} through integration of multiple signals across the whole spectral region in the

spectra. This method was chosen for its robust nature and ability to account for the presence of regiodefects when needed. Integral regions were slightly adjusted to increase applicability across the whole range of encountered comonomer contents. For systems where only isolated ethylene in PPEPP sequences was observed the method of Wang et al. was modified to reduce the influence of non-zero integrals of sites that are known to not be present. This approach reduced the overestimation of ethylene content for such systems and was achieved by reduction of the number of sites used to determine the absolute ethylene content to:

E = 0.5 (SPP + S bg + Xbd + 0.5( Xab + Say))

Through the use of this set of sites the corresponding integral equation becomes:

E = 0.5 (IH +IG + 0.5(Ic+ ID))

using the same notation used in the article of Wang et al. {6} . Equations used for absolute propylene content were not modified.

The mole percent comonomer incorporation was calculated from the mole fraction:

E [mol%] = 100 * fE

The weight percent comonomer incorporation was calculated from the mole fraction: E [wt%] = 100 * (fE * 28.06 ) / ( (fE * 28.06) + ((l-fE) * 42.08) )

Bibliographic references:

1) Busico, V., Cipullo, R., Prog. Polym. Sci. 26 (2001) 443.

2) Busico, V., Cipullo, R., Monaco, G., Vacatello, M., Segre, A.L.,

Macromolecules 30 (1997) 6251.

3) Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187 (2007) 225. 4) Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 1128.

5) Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100,

1253.

6) Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157.

7) Cheng, H. N., Macromolecules 17 (1984), 1950.

8) Singh, G., Kothari, A., Gupta, V., Polymer Testing 28 5 (2009), 475.

9) Kakugo, M., Naito, Y., Mizunuma, K., Miyatake, T. Macromolecules 15

(1982) 1150.

10) Randall, J. Macromol. Sci., Rev. Macromol. Chem. Phys. 1989, C29, 201.

11) Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100,

1253. d) Transparency, Haze and Clarity

All optical parameters were measured on 50pm thick cast films or blown films. Transparency, haze and clarity were determined according to ASTM D 1003. e) Tensile modulus

Tensile modulus in machine direction (TM-MD) and transverse direction (TM-TD) were measured according to ASTM D 882. f) Dart drop impact strength

Dart drop impact strength (DDI) was measured according to ISO 7765-1 : 2004. g) Adhesion and layer defects

The adhesion between the film layers and layer defects was evaluated by visual inspection.

Sample Preparation: Sections of 10 pm thickness were prepared on a Leica UC7/FC7 cryo -ultra-microtome at -80 °C Layer structure analysis: Cross-section samples were imaged on a Carl Zeiss

Axioscope.Al light microscope in Dark-field, polarized mode at magnification in the range 50x - 500x. h) Surface tension

The surface tension of the inner surface and the outer surface of the multi-layered films were measured according to ASTM D 2578

2. Materials

The following commercially available materials were used in the examples: a) Polyolefin resins:

FB2230 linear low density polyethylene with a MFR (l90°C, 2.16 kg) of 0.25 g/lO min and a density of 923 kg/m³, commercially available from Borouge Pte Ftd

RD368CF propylene-ethylene random copolymer with a MFR (230°C, 2.16 kg) of 8 g/lO min, commercially available from Borouge Pte Ftd

HD915CF propylene homopolymer with a MFR (230°C, 2.16 kg) of 8 g/lO min, commercially available from Borouge Pte Ftd b) EVOH resins:

F171B Eval F171B is a 32 mol% ethylene-vinyl alcohol copolymer with a

MFR (l90°C, 2.16 kg) of 1.6 g/lO min and a density of 1.19 · 10³ kg/m³, commercially available from Kuraray c) Tried as Coupling agents:

FG 1901 GT linear triblock copolymer based on styrene polymer and ethylene/ 1 - butene random copolymer grafted with maleic anhydride with a styrene polymer content of 30 mol%, a maleic anhydride content of 2 wt% and a MFR (230°C, 5 kg) of 22 g/lO min, commercially available from Kraton

G 1645 linear triblock copolymer based on styrene polymer and ethylene/ 1 - butene random copolymer with a styrene polymer content of 12 mol%, and a MFR (230°C, 2.16 kg) of 2.0-4.5 g/lO min, commercially available from Kraton

G1657 linear triblock copolymer based on styrene polymer and ethylene/ 1- butene random copolymer with a styrene polymer content of 13 mol%, and a MFR (230°C, 5 kg) of 22 g/lO min, commercially available from Kraton

PRIEX 20097 propylene homopolymer grafted with maleic anhydride with a maleic anhydride content of 0.45 % and a MFR (l90°C, 2.16 kg) of 25-30 g/lO min, commercially available from BYK-Chemie GmbH

QE800E Admer QE800E is a propylene homopolymer grafted with maleic anhydride and a MFR (230°C, 2.16 kg) of 9.1 g/lO min, commercially available from Mitsui Chemicals

AT 1179E Admer AT 1179E is a polypropylene grafted with maleic anhydride and a MFR (230°C, 2.16 kg) of 4.8 g/lO min, commercially available from Mitsui Chemicals

MA00930PP Constab MA930 PP is a masterbatch for polymer modification

containing 60% of a fully hydrogenated hydrocarbon resin.

3. Preparation of blown films with a polyethylene based core layer

Three-layer blown films were produced with

a core layer of 30 pm thickness of FB2230 and different coupling agents in different amounts,

an outer layer of 10 pm thickness of EVAL F171B and

an inner layer of 10 pm thickness of EVAL F171B and different coupling agents in different amounts. The three layers were co-extruded using a lab scale blown film line manufactured by COLLIN and blown to three-layer films as shown below in Table 1.

Inner layer:

The melt temperature was adapted to be around l95°C. The melt pressure was around 105 bar. The screw speed was around 35 rpm. The throughput was around 2000 g/hr.

Core layer:

The melt temperature was adapted to be around l950°C. The melt pressure was around 330 bar. The screw speed was around 60 rpm. The throughput was around 6000 g/hr.

Outer layer:

The melt temperature was adapted to be around 200°C. The melt pressure was around 75 bar. The screw speed was 25 rpm. The throughput was around 66000 g/hr.

The total throughput was around 74 kg/hr, the die gap was 1.8, and the blow up ratio was around 2.5.

Table 1 : Blown three-layer films

The blown films of examples IE1, IE2 and CE2 were additionally inspected in regard of their adhesion properties and appearance using a microscope.

Fig 1 shows the image of the cross-section of the three-layer film of IE2. The total film thickness is 40 pm (7/26/7). No delamination is observed between the layers. The interface between the core layer and the outer layer on the outer side (left side of the image) is seen to be diffuse, whereas a more distinct and sharper interface between the core layer and the inner layer can be seen on the inner side (right side of the image). Visually it appears that the interface between the core layer and the inner layer is not as strong as the interface between the core layer and the outer layer.

On top of good adhesion the film also shows good optical properties and no defects. Fig 2 shows the image of the cross-section of the three-layer film of IE1. The total film thickness is 50 pm (5/40/5). No delamination is observed between the layers. The interfaces between the core layer and the outer layer on the outer side (left side of the image) and the core layer and the inner layer on the inner side (right side of the image) are seen to be diffuse and cannot be resolved further with polarized light microscopy.

Fig. 3 shows the image of the cross-section of the three-layer film of CE2 when sectioning is attempted on the microtome. Both the inner and outer layer of the film are seen to delaminate very easily, and it appears that there is practically no adhesion between the layers.

The blown films of examples IE2, RE1 and CE2 were additionally subjected to mechanical tests which are shown below in Table 2. Table 2: Mechanical properties of examples IE2 and CE2

4. Analysis of a cup made of three layers according to the Klear Can

concept

A cup with the following structure was found to be:

a core layer of a EVOH polymer,

an outer layer of a random copolymer PP and an inner layer of a random copolymer PP

The three layers were coextruded and molded into a cup. The cup was inspected in regard of its adhesion properties and appearance using a microscope.

Fig 4 shows the image of the cross-section of the cup. Thereby, the top shows the inner layer and the bottom shows the outer layer of the cup.

Delamination is observed between the outer layer and the core layer, indicating poor or no adhesion between these layers. The interface between the inner layer and the core layer is found to be intact without any delamination observed.

Fig 5 shows the image of the inner side of the cup. Cracks can be seen in the inner layer of the cup.

Fig 6 shows the image of a cross-section of the cup at an angle which also shows the crack propagation on the inner side of the cup. Thereby, the top shows the outer layer and the bottom shows the inner layer of the cup.

The cross-section analysis shows that the cracks on the inner side of the cup are located within the inner layer only and are not propagated through the entire wall of the cup.

5. Preparation of cast films with a EVOH core layer and polypropylene based sandwich layers

Three-layer cast films were produced with

a core layer of 18 pm thickness of EVAL F171B,

chill roll side layer of 6 pm thickness of RD368CF and different coupling agents in different amounts and an air knife side layer of 6 mih thickness of RD368CF and different coupling agents in different amounts.

The three layers were co-extruded using a lab scale cast film line manufactured by COLLIN and cast to three-layer films as shown below in Table 3.

Chill roll side layer:

The melt temperature was adapted to be around 220°C. The melt pressure was around 50 bar. The screw speed was 30 rpm. The throughput was around 1265 g/hr. Core layer:

The melt temperature was adapted to be around 2lO°C. The melt pressure was around 60 bar. The screw speed was 24 rpm. The throughput was around 3700 g/hr.

Air knife side layer:

The melt temperature was adapted to be around 222°C. The melt pressure was around 50 bar. The screw speed was 22 rpm. The throughput was around 1250 g/hr.

The total throughput was around 6.2 kg/hr. the chill roll temperature was 50°C, and the chill roll speed was around 12 m/min.

The films were visually inspected regarding adhesion properties and appearance.

Table 3: Three-layer cast films

Summary

A coupling agent based on a styrene block copolymer modified with maleic anhydride units improves adhesion and mechanical properties of three layer films both with polyolefin core layer and with EVOH core layer.

A higher amount of the styrene block copolymer modified with maleic anhydride units of 10 wt% shows better adhesion compared to 5 wt%.

The styrene block copolymer modified with maleic anhydride units does not affect the optical properties of the three-layered films.

Addition of styrene block copolymer modified with maleic anhydride units to the EVOH layer can be considered as soon as oxygen barrier properties of EVOH including the styrene block copolymer modified with maleic anhydride units are guaranteed.

Claims

1. A multi-layered article comprising at least two layers (A) and (B) in adherent contact with each other, wherein

2. The multi-layered article according to claim 1, wherein the polymer composition (PC-B) of layer (B) comprises from 2.5 to 13.0 wt% of a non-polar

thermoplastic elastomer modified with polar groups.

3. The multi-layered article according to claim 1 or 2, wherein the non-polar

thermoplastic elastomer is a styrene block copolymer, preferably a block copolymer of styrene polymer units and ethylene/ 1 -butene random copolymer units.

4. The multi-layered article according to any one of the preceding claims, wherein the polar groups are selected from organic acid derivatives such as organic acid anhydrides or organic acid esters.

5. The multi-layered article according to any one of the preceding claims, wherein the non-polar thermoplastic elastomer modified with polar groups is a block copolymer of styrene polymer units and ethylene/ 1 -butene random copolymer units grafted with from 0.1 to 5.0 wt% maleic anhydride units.

6. The multi-layered article according to any one of the preceding claims, wherein the polyolefin in the polymer composition (PC-B) is selected from ethylene homo- or copolymers such as high density polyethylene and linear low density polyethylene and propylene homo- or copolymers such as propylene

homopolymers and propylene random copolymers.

7. The multi-layered article according to any one of the preceding claims, wherein the multi-layered article is free from tie layers.

8. The multi-layered article according to any one of the preceding claims, wherein the multi-layered article further comprises a layer (C) in adherent contact with layer (B).

9. The multi-layered article according to claim 8, wherein the layer (C) comprises the same polymer composition (PC- A) as layer (A).

10. The multi-layered article according to any one of the preceding claims being a three-layered film with the layer structure (A)-(B)-(C).

11. The multi-layered article according to any one of the preceding claims, wherein the multi-layered article further comprises a layer (D) in adherent contact with layer (A).

12. The multi-layered article according to claim 10, wherein the layer (D) comprises the same polymer composition (PC-B) as layer (B).

13. The multi-layered article according to any one of the preceding claims being a three-layered film with the layer structure (B)-(A)-(D).

14. The multi-layered article according to any one of the preceding claims being a multi-layered blown film, a multi-layered cast film, a multi-layered biaxially oriented film, a multi-layered molded article or a multi-layered thermoformed article.

15. The multi-layered article according to any one of the preceding claims having a total cross-sectional thickness of from 20 pm to 500 pm.

16. The multi-layered article according to any one of the preceding claims having a tensile modulus both in machine direction (TM-MD) and in transverse direction (TM-TD) of at least 750 MPa, measured according to ASTM D 882.

17. The multi-layered article according to any one of the preceding claims having a dart drop impact of at least 200 g, measured according to ISO 7765-1 : 2004 on a film having a cross-sectional thickness of 50 pm.

18. The multi-layered article according to any one of the preceding claims having a surface tension on both surfaces of at least 30 mN/m, measured according to ASTM D 2578.

19. The use of a non-polar thermoplastic elastomer modified with polar groups in at least one layer (B) of a multi-layered article for improving adhesion of the at least two layers (A) and (B) in adherent contact with each other, wherein layer (A) comprises polymer composition (PC-A) comprising an ethylene- vinyl alcohol copolymer, and