Polymer blend for the production of a MONO-axially oriented film

Abstract

The present disclosure relates to a polymer blend (I) comprising: A) a first polyethylene component in a wt.% A amount from 5 to 80 wt.%, having a density DA from 0.926 to 0.945 g / cm3, a Melt Index MIE from 0.1 to 3 g / 10 min and Mw / Mn of 7 or greater; B) a second polyethylene component in a wt.% B amount from 5 to 80 wt.%, having a density DB from 0.949 to 0.965 g / cm3, a Melt Index MIF from 5 to 28 g / 10 min. and a ratio MIF / MIP from 5 to 10.5; C) a third polyethylene component in a wt.% C amount from 10 to 40 wt.%, having a density DC from 0.949 to 0.965 g / cm3, a Melt Index MIF from 10 to 40 g / 10 min. and a ratio MIF / MIP from 11 to 30; wherein the wt.% A of the first polyethylene component A), the wt.% B of second polyethylene component B) and the wt.% C of third polyethylene component C) are with respect to the overall weight of A) + B) + C).

Description

Basell Polyolefine GmbH FE7701-EP-P1POLYMER BLEND FOR THE PRODUCTION OF A MONO-AXIALLY ORIENTED FILMFIELD OF THE INVENTION

[0001] The present disclosure relates to a polymer blend, a mono-axially oriented polymer film comprising said blend, and a method of production of the mono-axially oriented polymer film.BACKGROUND OF THE INVENTION

[0002] Polymeric films are widely used, both in industrial manufacturing processes and in the nonindustrial sector for the wholesale and retail delivery of goods to the consumer market.

[0003] Currently, films composed of ethylene based thermoplastic polymers dominate certain of these market applications, such as the market for household disposables, trash bags and liners; overwrap films and bags for laundry and dry cleaning goods; and shipping and carryout bags for retail merchandising of non-perishable goods. In other aspects of the consumer goods delivery market, ethylene based polymer films only weakly compete, if at all, with other more expensive polymer films such as plasticized polyvinyl chloride films and / or polypropylene films, such as in the heat-shrink wrap film market for the taut-contour fit wrapping of various items, particularly perishables such as cuts of meat, poultry, and fish. Yet for other applications, such as for packaging of produce, package constructions for cereals, dry foods, and snack foods ethylene based polymer films compete somewhat in certain circumstances of these applications.

[0004] Due to their valuable mechanical and optical properties, oriented polymeric films are increasingly requested for packaging applications.

[0005] Examples of oriented polyethylene films are disclosed in WO9722470, WO9821276 and CN113969007 A.

[0006] However, to achieve an optimal profile of properties, oriented polymeric films, including the mono-axially oriented films, generally have a multiple layer structure, with layers of different polymeric materials, like for instance polypropylene, polyethylene, polyethylene terephthalate, polyamides, ethylene polyvinyl alcohol.

[0007] Such complex structures require complex processing in the film preparation and are hardly compliant with the present sustainability and recyclability requirements.Basell Polyolefine GmbH FE7701-EP-P1

[0008] An attractive candidate for the preparation of mono-axially oriented films with reduced complexity, in terms of composition and structure, is polyethylene, in particular the high density polyethylene (HDPE).

[0009] In fact, HDPE can potentially achieve high mechanical properties, as it can be oriented up to relatively high stretch ratios.

[0010] Moreover, HDPE can achieve valuable optical properties, when properly treated.

[0011] However, the use of HDPE in the preparation of oriented films has been strongly limited by processing difficulties, resulting into often insufficient final properties.

[0012] The object of the present disclosure is to provide a polymer blend, a use thereof, a method of production of a mono-axially oriented polymer film and a mono-axially oriented polymer film that allow the drawbacks of the known art to be at least partially overcome, and which are, at the same time, simple and inexpensive to implement.SUMMARY OF THE INVENTION

[0013] Thus the present disclosure provides a polymer blend (I) comprising:A) a first polyethylene component in a wt.% A amount from 5 to 80 wt.%, preferably from 10 to 75 wt.%, more preferably from 15 to 65 wt.%, said first polyethylene component having a density DAfrom 0.926 to 0.945 g / cm3, preferably from 0.928 to 0.945 g / cm3, a Melt Index MIE from 0.1 to 3 g / 10 min andMw / Mn of 7 or greater, preferably of 8 or greater;B) a second polyethylene component in a wt.% B amount from 5 to 80 wt.%, preferably from 10 to 75 wt.%, more preferably from 15 to 65 wt.%, said second polyethylene component having a density DBfrom 0.949 to 0.965 g / cm3, preferably from 0.952 to 0.965 g / cm3, more preferably from 0.949 to 0.958 g / cm3or from 0.952 to 0.958 g / cm3, a Melt Index MIF from 5 to 28 g / 10 min., preferably from 5 to 24 g / 10 min. and a ratio MIF / MIP from 5 to 10.5, preferably from 5 to 10, more preferably from 6 to 9.5; andC) a third polyethylene component in a wt.% C amount from 10 to 40 wt.%, preferably from 15 to 35 wt.%, more preferably from 20 to 30 wt.%, said third polyethylene component having a density Dcfrom 0.949 to 0.965 g / cm3, preferably from 0.952 to 0.965 g / cm3, more preferably from 0.949 to 0.958 g / cm3or from 0.952 to 0.958Basell Polyolefine GmbH FE7701-EP-P1 g / cm3, a Melt Index MIF from 10 to 40 g / 10 min., preferably from 15 to 35 g / 10 min. and a ratio MIF / MIP from 11 to 30, preferably from 11.5 to 25, more preferably from 12 to 20; wherein the wt.% A of the first polyethylene component A), the wt.% B of second polyethylene component B) and the wt.% C of third polyethylene component C) are with respect to the overall weight of A) + B) + C).The expression “wt.%” means % by weight.

[0014] The mono-axially oriented polyethylene films obtained from said polymer blend have surprisingly good optical (in particular, haze and gloss) and mechanical (in particular, tensile) properties.DETAILED DESCRIPTION OF THE INVENTION

[0015] Preferably the value of the relation: wt.% A*DA+ wt.% B*DB

[0016] is equal to or lower than 85, preferably equal to or lower than 80, the preferred lower limit being of 55 or 60 in all cases.

[0017] In the present text: MIF indicates the Melt Index measured with 21.6 kg at 190°C; MIP indicates the Melt Index measured with 5 kg at 190°C; and MIE indicates the Melt Index with 2.16 kg at 190°C.

[0018] The first polyethylene component A) and the second polyethylene component B) and the third polyethylene component C) can be selected from ethylene homopolymers and ethylene copolymers containing alpha-olefin monomer units (preferably in amounts up to 10% by weight) and their mixtures. Examples of the said alpha-olefin monomer units are those having from 3 to 8 carbon atoms, in particular propylene, 1 -butene, 1 -pentene, 1 -hexene, 1 -octene and 4- methyl-1 -pentene. 1 -butene and 1 -hexene are preferred.

[0019] Said homopolymers and copolymers can be obtained by way of polymerization processes in the presence of coordination catalysts. Said processes and the homopolymers and copolymers obtained from them are widely described in the art.

[0020] In particular it is possible to carry out the polymerization process in the presence of a Ziegler-Natta catalyst or single site catalyst.Basell Polyolefine GmbH FE7701-EP-P1

[0021] As is well known, a Ziegler-Natta catalyst comprises the product of the reaction of an organometallic compound of group 1, 2 or 13 of the Periodic Table of elements with a transition metal compound of groups 4 to 10 of the Periodic Table of Elements (new notation). In particular, the transition metal compound can be selected among compounds of Ti, V, Zr, Cr and Hf and is preferably supported on MgCh.

[0022] Particularly preferred catalysts comprise the product of the reaction of said organometallic compound of group 1 , 2 or 13 of the Periodic Table of elements, with a solid catalyst component comprising a Ti compound supported on MgCh.

[0023] Preferred organometallic compounds are the organo-Al compounds.

[0024] The single site catalysts are known in the art and are generally selected from metallocene and non-metallocene single site catalysts.

[0025] Examples of metallocene single site catalysts are zirconocenes and hafnocenes, for instance cyclopentadienyl or indenyl complexes of zirconium or hafnium, like bis (cyclopentadienyl) zirconium dichloride; bis (indenyl) zirconium dichloride or bis (indenyl) hafnium dichloride.

[0026] Examples of non-metallocene single site catalysts are iron complex compounds preferably having a tridentate ligand.

[0027] Particularly suited tridentate ligands are 2,6-Bis[l-(phenylimino)ethyl] pyridine and preferably the corresponding compounds wherein both the two phenyl groups are substituted in the ortho-position with a halogen or tert, alkyl substituent.

[0028] Specific examples are 2,6-Bis[l-(2-tert.butylphenylimino)ethyl]pyridine iron(II) dichloride; 2,6-Bis[l-(2-tert.butyl-6-chlorophenylimino)ethyl]pyridine iron(II) dichloride or 2,6- Bis[l -(2,4-dichlorophenylimino)ethyl]pyridine iron(II) dichloride.

[0029] Said metallocene and non-metallocene single site catalysts can also be used in combination.

[0030] Preferably, the single site catalysts are reacted with activating compounds (cocatalysts), preferred examples of which are aluminoxanes, such as mono-methylaluminoxane (MAO), for instance.

[0031] The polymerization, which can be continuous or batch, is carried out, in the presence of said catalysts, following known techniques and operating in liquid phase, in the presence or not of inert diluent, or in gas phase, or by mixed liquid-gas techniques.Basell Polyolefine GmbH FE7701-EP-P1

[0032] Reaction time, pressure and temperature relative to the polymerization steps are not critical, however it is best if the temperature is from 50 to 100°C. The pressure can be atmospheric or higher.

[0033] The regulation of the molecular weight is carried out by using known regulators, hydrogen in particular.

[0034] In addition to the said components A), B) and C), the present polymer blend (I) can also comprise a further (fourth) polyethylene component D) comprising one or more ethylene polymers having a density of lower than 0.926 g / cm3, in particular equal to or lower than 0.925 g / cm3, more preferably equal to or lower than 0.924 g / cm3, the preferred lower limit being of 0.910 g / cm3in all cases.

[0035] Preferred amounts of component D) are from 2 to 30 wt.%, more preferably from 5 to 25 wt.%, referred to the total weight of A) + B) + C) + D).

[0036] Said ethylene polymers present in polyethylene component D) are preferably selected from LLDPE (linear low density polyethylene), LDPE (low density polyethylene) and their mixtures.

[0037] Preferably both the said LLDPE and LDPE have a Melt Index MIE from 0.1 to 3 g / 10 min.

[0038] Both LLDPE and LDPE are selected from ethylene homopolymers and copolymers.

[0039] Examples of LLDPE copolymers include copolymers containing the same alpha-olefin monomer units, in particular containing from 3 to 8 carbon atoms, as previously described.

[0040] Both LLDPE homopolymers and copolymers can be obtained by way of the same coordination catalysts and polymerization processes as previously described for the preparation of polyethylene components A), B) and C).

[0041] Examples of LDPE copolymers include ethylene-vinyl acetate copolymers, ethylenevinyl alcohol copolymers, ethylene-acrylate copolymers, ethylene-methacrylate copolymers, ethylene copolymers containing alpha-olefin monomer units and mixtures thereof.

[0042] Suitable examples of alpha-olefin monomer units in the LDPE copolymers are the same as previously described.

[0043] There are two basic high pressure polymerization processes for the manufacture ofLDPE: autoclave and tubular.Basell Polyolefine GmbH FE7701-EP-P1

[0044] The LDPE made by the autoclave reactor process has a high concentration of long chain branches, resulting into high values of elongational hardening, and a relatively broad molecular weight distribution that make it easy to process.

[0045] The autoclave polymerization is generally carried out in the presence of radical initiating agents selected from organic peroxides.

[0046] The tubular reactor process does not necessarily require the use of organic peroxides. It can be carried out by using oxygen alone as the radical initiating agent, thus allowing to prepare a LDPE which is free from the products of chemical degradation of organic peroxides.

[0047] The said LDPE can also be prepared with a mixed process combining both autoclave and tubular reactors.

[0048] Process operating conditions can include, but are not limited to, a pressure in the range of from 70 MPa to 700 MPa and a temperature in the range of from 150°C to 500°C.

[0049] The polymerization can be carried out in the presence of one or more chain transfer agents known in the art, such as propylene, propane and propionic aldehyde.

[0050] Such chain transfer agents are used to regulate the molecular weights.

[0051] The said processes and the resulting LDPE product are well known in the art. For instance, US patent. No. 3,691,145 and US patent application No. 2010 / 0076160 teach producing LDPE in a tubular reactor process.

[0052] In general, the term “copolymer” is meant to include also polymers containing more than one kind of comonomers, such as terpolymers.

[0053] All the said ethylene homopolymers and copolymers are available on the market. Specific commercial polymers suited for producing the present polymer blend (I) are described in the examples.

[0054] Advantageously but not necessarily, the first polyethylene component has tensile modulus up to 1000 MPa (in particular, up to 800 MPa).

[0055] According to some non-limiting embodiments, the first polyethylene component has tensile modulus of at least 100 MPa (in particular, at least 200 MPa; more in particular, at least 250 MPa).

[0056] Advantageously but not necessarily, the first polyethylene component has a weight average molecular weight Mw equal to or lower than 250000 g / mol (in particular, lower than 200000 g / mol).Basell Polyolefine GmbH FE7701-EP-P1

[0057] In some non-limiting cases, the first polyethylene component has a Mw equal to or higher than 90000 g / mol (in particular, equal to or higher than 100000 g / mol).

[0058] Advantageously but not necessarily, the first polyethylene component has a Mw / Mn equal to or lower than 25.0 (in particular, equal to or lower than 20.0).

[0059] According to some non-limiting embodiments, the first polyethylene component has a number average molecular weight Mn equal to or higher than 9000 g / mol; in particular, equal to or lower than 20000 g / mol (more in particular, equal to or lower than 17000 g / mol).

[0060] According to some non-limiting embodiments, the first polyethylene component has z-average molecular weight Mz equal to or lower than 800000 g / mol (in particular, equal to or lower than 750000 g / mol); in particular, equal to or higher than 200000 g / mol (more in particular, equal to or higher than 250000 g / mol).

[0061] Alternatively or additionally, the said first polyethylene component has MIF from 10 to 40 g / min.

[0062] Advantageously but not necessarily, the second polyethylene component has tensile modulus on compression molded plaque up to 2000 MPa (more particularly, up to 1800 MPa).

[0063] According to some non-limiting embodiments, the second polyethylene component has tensile modulus on compression molded plaque of at least 500 MPa (in particular, at least 600 MPa; more in particular, at least 800 MPa).

[0064] Advantageously but not necessarily, the second polyethylene component has a Mw equal to or lower than 250000 g / mol (in particular, lower than 200000 g / mol).

[0065] In some non-limiting cases, the second polyethylene component has a Mw equal to or higher than 90000 g / mol (in particular, equal to or higher than 100000 g / mol).

[0066] According to particularly preferred but not limiting embodiments, the second polyethylene component has a Mw / Mn equal to or lower than 20 (in particular, equal to or lower than 18).

[0067] In some non-limiting cases, the second polyethylene component has a Mw / Mn of 6.0 or greater, in particular of 7.0 or greater.

[0068] According to some non-limiting embodiments, the second polyethylene component has a Mn equal to or higher than 9000 g / mol; in particular, equal to or lower than 20000 g / mol (more in particular, equal to or lower than 17000 g / mol).Basell Polyolefine GmbH FE7701-EP-P1

[0069] According to some non-limiting embodiments, the second polyethylene component has Mz equal to or lower than 800000 g / mol (in particular, equal to or lower than 750000 g / mol); in particular, equal to or higher than 200000 g / mol (more in particular, equal to or higher than 250000 g / mol, or equal to or higher than 330000 g / mol).

[0070] Alternatively or additionally, the said second polyethylene component has MIE from 0.1 to 3 g / min., preferably from 0.1 to 2 g / 10min., in particular from 0.1 to 1.8 g / 10min., or from 0.1 to 1.3 g / 10min., or from 0.5 to 3 g / 10min., or from 0.5 to 2 g / 10min., or from 0.5 to 1.8 g / 10min., or from 0.5 to 1.3 g / lOmin.

[0071] Advantageously but not necessarily, the third polyethylene component has tensile modulus on compression molded plaque up to 2000 MPa (more particularly, up to 1800 MPa).

[0072] According to some non-limiting embodiments, the third polyethylene component has tensile modulus on compression molded plaque of at least 500 MPa (in particular, at least 600 MPa; more in particular, at least 800 MPa).

[0073] Advantageously but not necessarily, the third polyethylene component has a Mw equal to or lower than 350000 g / mol (in particular, lower than 300000 g / mol).

[0074] In some non-limiting cases, the third polyethylene component has a Mw equal to or higher than 90000 g / mol (in particular, equal to or higher than 100000 g / mol).

[0075] According to particularly preferred but not limiting embodiments, the third polyethylene component has a Mw / Mn equal to or lower than 30 (in particular, equal to or lower than 25).

[0076] In some non-limiting cases, the third polyethylene component has a Mw / Mn equal of 8.0 or greater, in particular of 10.0 or greater.

[0077] According to some non-limiting embodiments, the third polyethylene component has a Mn equal to or higher than 8000 g / mol; in particular, equal to or lower than 20000 g / mol (more in particular, equal to or lower than 18000 g / mol).

[0078] According to some non-limiting embodiments, the third polyethylene component has a Mz equal to or higher than 900000 g / mol (more in particular, equal to or higher than 1000000 g / mol, or equal to or higher than 1100000 g / mol) preferably equal to or lower than 2500000 g / mol (in particular, equal to or lower than 2000000 g / mol).

[0079] In all cases, Mw, Mn and Mz are measured with gel permeation chromatography (GPC).Basell Polyolefine GmbH FE7701-EP-P1

[0080] The present polymer blend (I) can also contain conventional additives.

[0081] Examples of these additives are heat stabilizers, antioxidants, UV absorbers, light stabilizers, metal deactivators, compounds which destroy peroxide, and basic costabilizers, typically in amounts of from 0.01 to 10 % by weight, preferably from 0.1 to 5 % by weight, with respect to the total weight of the polymer blend (I).

[0082] The present polymer blend (I) can be prepared by a process comprising a combination step, during which the said polyethylene components are combined by melting and mixing, and the mixing is effected in a mixing apparatus at temperatures generally of from 160 to 250°C.

[0083] Any known apparatus and technology can be used for this purpose.

[0084] Useful melt-mixing apparatus in this context are in particular extruders or kneaders, and particular preference is given to twin-screw extruders. It is also possible to premix the components at room temperature in a mixing apparatus.

[0085] The present mono-axially oriented polyethylene film can be monolayer or multilayer, wherein at least one layer comprises the present polymer blend (I).

[0086] The polymer blend (I) may be present in the mono-axially oriented polyethylene film in a weight amount of at least 40%, preferably of at least 60% in particular from 40 to 100% or from 60 to 100%.

[0087] The said amounts are with respect to the total weight of the film when it is a monolayer film, or with respect to the total weight of the layer or layers containing the polymer blend (I) for multilayer films.

[0088] As it is mono-axially oriented, the present film is stretched in one direction (only).

[0089] Preferably it is a machine direction oriented (MDO) film, hence it is stretched in the machine direction.

[0090] For “machine direction” it is meant the direction into which the film is extruded.

[0091] In particular, the present mono-axially oriented polyethylene film is stretched with a preferred stretch ratio from 3:1 to 10:1.

[0092] Preferably, the mono-axially oriented polyethylene film has a thickness equal to or smaller than 250 pm (in particular, equal to or smaller than 210 pm).

[0093] A preferred, but not limiting, lower limit is of 10 pm in all cases.Basell Polyolefine GmbH FE7701-EP-P1

[0094] In another embodiment, it is herein provided a method of production of the present mono-axially oriented polyethylene film.

[0095] More precisely but not necessarily, the mono or multilayer mono-axially oriented polyethylene film can be prepared with known processes.

[0096] Said processes comprise a stretching step carried out on a primary film comprising the present polymer blend (I).

[0097] In some non-limiting cases, the primary film before stretching has a thickness of at least 0.3 mm (in particular, at least 0.5 mm).

[0098] In general the primary film is conveyed through a series of rollers having different rotation speeds.

[0099] In particular the mono-axially oriented polyethylene film can be prepared using the flat die extrusion and cooling on chill rolls, or via annular die extrusion and air cooling of the blown film obtained. The so obtained primary film is then passed through a stretching unit by rollers moving faster than the rate at which the polymer is extruded. This orients the film in the machine direction (MD).

[0100] The film extrusion is carried out with known techniques, preferably operating at temperatures from 180 to 300°C.

[0101] In the orientation stage, carried out in the stretching unit, the main operative conditions are, preferably:- Pre-heating temperature: 120 - 130°C;- Pre-heating time: 60 - 100 sec. ;- Stretching speed: 15 - 40 mm / sec.;- Stretching rate: 30 - 50% / sec.;- Stretch ratio: 3:1 - 10:1.

[0102] After stretching, the film is heat-set to hold the orientation and then reeled up.

[0103] In all the said processes, heating can be carried out by using, for instance, IR lamps or hot air or other heating elements, like electrical resistance heaters.

[0104] The orientation provides balanced mechanical characteristics. Film orientation greatly improves film's tensile strength, flexibility, and toughness. Orientation also enables the films to be used for heat- shrinking applications.Basell Polyolefine GmbH FE7701-EP-P1

[0105] Preferably, the present mono-axially oriented polyethylene film has one or more of the following properties:Haze from 1.5 to 10%, more preferably from 1.5 to 8%;Gloss on film (at 45°C): from 50 to 100 GU, preferably from 60 to 95 GU;Tensile Modulus MD: from 500 to 2500 MPa.EXAMPLES

[0106] The practice and advantages of the various embodiments, compositions and methods as provided herein are disclosed below in the following examples. These examples are illustrative only, and are not intended to limit the scope of the appended claims in any manner whatsoever.

[0107] The following analytical methods are used to characterize the polymer compositions.

[0108] Melt flow index

[0109] Determined according to to ISO 1133-1 2012-03 at 190°C with the specified load.

[0110] Density

[0111] Determined according to ISO 1183-1 :2012 at 23°C, immersion method.

[0112] Tensile modulus

[0113] Determined according to ISO 527-2:2012 on compression molded plaques and ASTM D882- 18 on films.

[0114] Gloss

[0115] Determined according to ASTM D-2457-13.

[0116] Haze

[0117] Determined according to ASTM D-1003-13.

[0118] Molecular Weight Distribution Determination

[0119] The determination of the means Mw, Mn and Mz and of the molecular weight distribution Mw / Mn derived therefrom was carried out by high-temperature gel permeation chromatography using a method described in ISO 16014-1, -2, -4, issue of 2003. The specifics according to the mentioned ISO standards are as follows: Solvent 1,2,4-trichlorobenzene (TCB), temperature of apparatus and solutions 145 °C and as concentration detector a PolymerChar (Valencia, Paterna 46980, Spain) IR-4 infrared detector, capable for use with TCB. A WATERSBasell Polyolefine GmbH FE7701-EP-P1Alliance 2000 equipped with the following pre-column SHODEX UT-G and separation columns SHODEX UT 806 M (3x) and SHODEX UT 807 (Showa Denko Europe GmbH, Konrad-Zuse- Platz 4, 81829 Muenchen, Germany) connected in series was used.

[0120] The solvent was vacuum distilled under Nitrogen and was stabilized with 0.025% by weight of 2,6-di-tert-butyl-4-methylphenol. The flowrate used was 1 ml / min, the injection was 500pl and polymer concentration was in the range of 0.01% < cone. < 0.05% w / w. The molecular weight calibration was established by using monodisperse polystyrene (PS) standards from Polymer Laboratories (now Agilent Technologies, Herrenberger Str. 130, 71034 Boeblingen, Germany) in the range from 580g / mol up to 11600000g / mol and additionally with Hexadecane.

[0121] The calibration curve was then adapted to Polyethylene (PE) by means of the Universal Calibration method (Benoit H., Rempp P. and Grubisic Z., & in J. Polymer Sci., Phys. Ed., 5, 753(1967)). The Mark-Houwing parameters used herefore were for PS: kps= 0.000121 dl / g, aps=0.706 and for PE kpE= 0.000406 dl / g, apE=0.725, valid in TCB at 135°C. Data recording, calibration and calculation was carried out using NTGPC_Control_V6.02.03 and NTGPC V6.4.24 (hs GmbH, Hauptstrabe 36, D-55437 Ober-Hilbersheim, Germany) respectively.

[0122] Comonomer content

[0123] The comonomer content was determined by means of IR in accordance with ASTM D 6248 98, using an FT-IR spectrometer Tensor 27 from Bruker, calibrated with a chemometric model, for instance for determining ethyl- side-chains in PE for butene- 1 as comonomer and butyl- side-chains in PE for hexene- 1 as comonomer.

[0124] Examples 1-2 and Comparative Examples 1-2

[0125] These examples disclose the production of samples of MDO polyethylene films and the characteristics of the obtained films.

[0126] The following commercially available starting materials, sold by LyondellBasell Industries, have been used.Component A): Luflexen hyPE 35P FA (hyPE35), having the following features:MIE: 0.72 g / 10 min;- MIP: 2.17 g / 10 mm;- MIF: 31.34 g / 10 mm;Density: 0.936 g / cm3;Tensile modulus: 600 MPa;Basell Polyolefine GmbH FE7701-EP-P1Tensile Stress at Yield: 16 MPa.Component B): Luflexen hyPE 56P FA (hyPE56), having the following features:MIE: 0.77 g / 10 min;MIF: 18.8 g / 10min.;MIP: 2.18 g / 10 min.;- MIF / MIP: 8.6;Density: 0.955 g / cm3;Tensile modulus: 1220 MPa on compression molded plaque.Component C): Hostalen GF 9055 F (GF9055F), having the following features:MIE: 0.5 g / 10 min;MIF: 24 g / 10min.;MIP: 1.8 g / 10 min.;- MIF / MIP: 13.3;Density: 0.954 g / cm3;Tensile modulus: 1300 MPa on compression molded plaque.Component D): mixture of 17 wt.% of Petrothene GAI 810 and 3 wt.% Lupolen 2420F, referred to the total weight of A) + B) + C) + D), wherein:Petrothene GA1810 (GA1810) is a LLDPE having the following features:MIE: 1.0 g / 10 min;Density: 0.918 g / cm3.Lupolen 2420F (2420 F) is a LDPE having the following features:MIE: 0.75 g / 10 min;Density: 0.923 g / cm3.

[0127] The molecular weights of A) B) and C) are reported in Table 1 below.Table 1Basell Polyolefine GmbH FE7701-EP-P1

[0128] Samples of MDO polyethylene films with the following polymer blends (I) have been produced (the percentages are by weight with respect overall weight of the polymer blend).- Example 1: 30% hyPE35 + 30% hyPE56 + 20% GF9055F + 17% GA1810 + 3% 2420 F;- Example 2: 40% hyPE35 + 20% hyPE56 + 20% GF9055F + 17% GA1810 + 3% 2420 F;- Comparative Example 1 : 20% hyPE35 + 60% hyPE56 + 17% GAI 810 + 3% 2420 F;- Comparative Example 2: 40% hyPE35 + 40% hyPE56 + 17% GAI 810 + 3% 2420 F.

[0129] In order to obtain the MDO films the following procedure has been used.

[0130] A primary film having a thickness of 1 mm was prepared using a Leonard line with the following features and under the following conditions:Extruder diameter: 40 mm, L / D 27;Dosing gear pump;Flat die, with lip width 200 mm, die lip gap of 1 mm;Melt temperature: 240°C;3 chill rolls having a diameter of 160 mm, with roll temperature of 45°C;Film cutting unit.

[0131] From the primary film, 93 x 93 mm specimens were cut. The specimens were then oriented in the machine direction (MD) using a Brueckner KARO IV stretching unit, under the following conditions:Pre-heating temperature: 122°C;Heating time: 80 sec;Stretching speed: 28 mm / sec;Stretching rate: 40% / sec.;Stretching area: 70 x 70 mm (out of clamps);Stretch ratio: see Table 2.

[0132] The Brueckner KARO IV stretching unit was used to reproduce the mono-axial stretching step, which on industrial scale is generally carried out by conveying the film through rollers.

[0133] The MDO polyethylene films produced had the characteristics indicated in Table 2 below.Basell Polyolefine GmbH FE7701-EP-P1Table 2Table 2 cont.* with respect to the total weight of A) + B) + C) in Table 2, with respect to the total weight of A) + B) in Table 2 cont.; ** ± 9 pm; *** ±12 pm

[0134] As previously explained, MD means in the “machine direction”. In other words, it means that the measurement is carried out in the direction of the extrusion.

Claims

Basell Polyolefine GmbH FE7701-EP-P1CLAIMSWhat is claimed is:

1. A polymer blend (I) comprising:A) a first polyethylene component in a wt.% A amount from 5 to 80 wt.%, preferably from 10 to 75 wt.%, more preferably from 15 to 65 wt.%, said first polyethylene component having a density DAfrom 0.926 to 0.945 g / cm3, preferably from 0.928 to 0.945 g / cm3, a Melt Index MIE from 0.1 to 3 g / 10 min and Mw / Mn of 7 or greater, preferably of 8 or greater;B) a second polyethylene component in a wt.% B amount from 5 to 80 wt.%, preferably from 10 to 75 wt.%, more preferably from 15 to 65 wt.%, said second polyethylene component having a density DBfrom 0.949 to 0.965 g / cm3, preferably from 0.952 to 0.965 g / cm3, more preferably from 0.949 to 0.958 g / cm3or from 0.952 to 0.958 g / cm3, a Melt Index MIF from 5 to 28 g / 10 min., preferably from 5 to 24 g / 10 min. and a ratio MIF / MIP from 5 to 10.5, preferably from 5 to 10, more preferably from 6 to 9.5; andC) a third polyethylene component in a wt.% C amount from 10 to 40 wt.%, preferably from 15 to 35 wt.%, more preferably from 20 to 30 wt.%, said third polyethylene component having a density Dcfrom 0.949 to 0.965 g / cm3, preferably from 0.952 to 0.965 g / cm3, more preferably from 0.949 to 0.958 g / cm3or from 0.952 to 0.958 g / cm3a Melt Index MIF from 10 to 40 g / 10 min., preferably from 15 to 35 g / 10 min. and a ratio MIF / MIP from 11 to 30, preferably from 11.5 to 25, more preferably from 12 to 20; wherein the wt.% A of the first polyethylene component A), the wt.% B of second polyethylene component B) and the wt.% C of third polyethylene component C) are with respect to the overall weight of A) + B) + C); the density is determined according to ISO 1183-1 : 2012 at 23 °C, immersion method; the Melt Index MIE is determined at 190°C with a load of 2.16 kg, the Melt Index MIF is determined at 190°C with a load of 21.6 kg, MIPBasell Polyolefine GmbH FE7701-EP-P1 is the Melt Index determined at 190°C with a load of 5 kg, all according to ISO 1133-1 2012-03; Mw and Mn are respectively the weight average molecular weight and the number average molecular weight, both measured with gel permeation chromatography.

2. The polymer blend (I) of claim 1 , further comprising a polyethylene component D) comprising one or more ethylene polymers having a density of lower than 0.926 g / cm3, in particular equal to or lower than 0.925 g / cm3, more preferably equal to or lower than 0.924 g / cm3, the preferred lower limit being of 0.910 g / cm3in all cases.

3. The polymer blend (I) of claim 2, wherein the amount of component D) is from 2 to 30 wt.%, preferably from 5 to 25 wt.%, referred to the total weight of A) + B) + C).

4. The polymer blend (I) according to Claim 1 or 2, wherein said second polyethylene component B) has a Mw / Mn of 6.0 or greater, in particular of 7.0 or greater.

5. The polymer blend (I) according to Claim 1 or 2, wherein said first and / or second polyethylene components A) and B) have a z-average molecular weight Mz equal to or lower than 800000 g / mol, measured with gel permeation chromatography (GPC).

6. The polymer blend (I) according to Claim 1 or 2, wherein said third polyethylene component C) has a z-average molecular weight Mz equal to or higher than 900000 g / mol preferably equal to or higher than 1000000 g / mol, measured with gel permeation chromatography (GPC).

7. The polymer blend (I) according to Claim 1 or 2, wherein said second and / or third polyethylene components B) and C) have tensile modulus, determined on compression molded plaque according to ISO 527-2:2012, of at least 500 MPa, in particular at least 600 MPa, more in particular, at least 800 MPa.

8. The polymer blend (I) according to Claim 1 or 2, wherein said third polyethylene component C) has a Mw / Mn of 8.0 or greater, in particular of 10.0 or greater.

9. The polymer blend (I) according to Claim 1 or 2, wherein said second polyethylene component B) has MIE from 0.1 to 3 g / min., preferably from 0.1 to 2 g / 10min., inBasell Polyolefine GmbH FE7701-EP-P1 particular from 0.1 to 1.8 g / 10min., or from 0.1 to 1.3 g / 10min., or from 0.5 to 3 g / 10min., or from 0.5 to 2 g / 10min., or from 0.5 to 1.8 g / 10min., or from 0.5 to 1.3 g / lOmin.

10. A mono-axially oriented polymer film consisting of or comprising a polymer blend (I) according to any one of Claims 1 to 9.

11. The mono-axially oriented polymer film according to Claim 10, having a thickness equal to or smaller than 250 pm.

12. The mono-axially oriented polymer film according to Claim 10 or 11, which is a machine direction oriented (MDO) film.

13. The mono-axially oriented polymer film according to any of Claims 10 to 12, stretched with a stretch ratio from 3: 1 to 10: 1, preferably in machine direction (MD).

14. Method of production of the mono-axially oriented polymer film according to any of Claims 10 to 13, comprising a stretching step, during which a primary film comprising the polymer blend (I) according to any one of Claims 1 to 9 is stretched in one direction, preferably in machine direction (MD).

15. The method according to Claim 14, wherein the primary film has a thickness of at least 0.3 mm.

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