Title of Invention	NOVEL POLYOLEFIN COMPOSITIONS AND DRAWN TAPES, FIBRES AND FILAMENTS PRODUCED THEREFROM
Abstract	The invention relate to a novel polyolefin composition which is suitable for producing drawn tapes, fibres and filaments which have improved mechanical properties. The composition comprises A) 2 30wt% of a propylene copolymer which comprises as a) random propylene copolymer having a content of ethylene and/ or C 4-C 8a-olefin og 0.5 to 12wt% and optionally an (b) ethylene-a-olefin rubber.B0 70 98wt% of high density polyethylene having a density of 930 to 965kg/m3 and a MFR (190"C/2.16kg) of 0.3 to 20g/10min.

Title of Invention

NOVEL POLYOLEFIN COMPOSITIONS AND DRAWN TAPES, FIBRES AND FILAMENTS PRODUCED THEREFROM

Abstract

The invention relate to a novel polyolefin composition which is suitable for producing drawn tapes, fibres and filaments which have improved mechanical properties. The composition comprises A) 2 30wt% of a propylene copolymer which comprises as a) random propylene copolymer having a content of ethylene and/ or C 4-C 8a-olefin og 0.5 to 12wt% and optionally an (b) ethylene-a-olefin rubber.B0 70 98wt% of high density polyethylene having a density of 930 to 965kg/m3 and a MFR (190"C/2.16kg) of 0.3 to 20g/10min.

Full Text	NOVEL POLYOLEFIN COMPOSITIONS AND DRAWN TAPES, FIBRES AND FILAMENTS PRODUCED THEREFROM The present invention relates to a novel poiyolefin composition which is suitable for producing drawn tapes, fibres and filaments which have improved mechanical properties. Polyethylene is one of the materials used for the production of stretch tapes and monofilaments. The applications for tape and monofilaments are ranging from nets and ropes for marine, fishing and agricultural applications, geotextiles, nets for packaging and several other applications. Higher drawability and tenacity will allow to develop new applications and will allow down gauging. Improving the mechanical properties of polypropylene tapes and monofilaments by blending in polyethylene Is well known and often applied. However, improving the properties of polyethylene tapes and monofilaments by blending in polypropylene is rather unknown. Some experience does exist in the form of tapes produced from blends of polyethylene with a minor amount of propylene homopolymer. The problem however Is, that in these blends the film appearance is poor. Object It is the object of this invention to provide novel poiyolefin compositions, where drawn tapes, fibres and filaments made from these poiyolefin compositions have an Improved mechanical performance compared to tapes, fibres and filaments made from the basic ethylene polymer. Particularly, it Is desirable that the tapes, fibres and filaments either have an improved elongation at break or an improved tenacity compared to the respective fibre, tape or filament made from the baste ethylene polymer. It is particularly preferred, that at least the elongation at break is improved compared to the basic ethylene polymer. It is especially preferable that both the elongation at break and the tenacity are improved compared to the respective fibre, tape or filament made from the basic ethylene polymer. The above mentioned problem is solved by blending a small amount of a propylene copolymer with a high density polyethylene. Tapes and monofilaments made from such a composition have a higher drawability and an improved tenacity-elongation balance. More particularly, the aforementioned object is achieved with a polyolefin composition comprising A) 2 - 30 wt% of a propylene copolymer which comprises a a) random propylene copolymer having a content of ethylene and/or C4-C6 a-olefin of 0.5 to 12 wt% and optionally an b) ethylene-cwiefin rubber, B) 70 - 98 wt% of a high density polyethylene having a density of 930 to 965 kg/m3 and a MFR (190 °C/2.16 kg) of 0.3 to 20 g/10 min. Generally, the amount of propylene copolymer in the polyolefin composition of the invention ranges from 2-30 wt%, preferably from 3-25 wt% and more preferably from 5-20 wt%. A necessary component of the propylene copolymer is a random propylene copolymer. A random propylene copolymer according to the present invention is a random propylen-copolymer produced by statistical Insertion of units of ethylene and/or C4-C8 Orolefins. As comonomers the random propylene copolymer according to the present invention may contain ethylene and/or one or more C4-CS Orolefins. Suitable Oroiefins may be linear or branched. Preferred ct-oiefins are 1-butene, 1-hexene, 1-octene and 4-methyl-1-pentene. Ethylene and 1-butene are especially prefenred as comonomers. According to the invention, it is prefend that the random propylene copolymer either is a binary copolymer of propylene with ethylene or a binary copolymer of propylene with 1-butene or a terpolymer of propylene with ethylene and 1-butene. According to the present Invention the used random copolymer preferably has a comonomer content of 0.5 to 12 wt%, preferably 1 to 11 wt%. For a binary copolymer of propylene with ethylene the preferred comonomer content is 0.5 to 8 wt%, more preferably 1 to 7 wt%, even more preferably 2 to 6 wt%. For a binary copolymer of propylene with 1-butene the preferred comonomer content is 0.5 to 10 wt%, more preferably 1 to 9, even more preferably 2 to 8 wt%. For a terpolymer of propylene with ethylene and 1-butene the total comonomer content preferably is 0.5 to 16wt%, more preferably 1 to 13wt%, even more preferably 2 to 10 wt%. For a terpolymer the ethylene content is preferably smaller than the 1-butene content and the prefenred ratio of ethylene content to 1-butene content Is s 0.5, more preferable s 0.3. Further, for a terpolymer of propylene with ethylene and 1-butene the prefen-ed content of ethylene Is from 0.3 - 3 wt% and tiie prefend 1-butene content is from 0.7- 15wt%. According to an optional embodiment the propylene copolymer used in the present Invention comprises an ethyiene-Orolefin rubber. It has surprisingly been found that compositions where the propylene copolymer comprises a random propylene copolymer and an ethylene-CK)lefln rubber also show a level of mechanical properties which - on average - are improved compared to compositions containing no modifier or a propylene homopolymer as modifier. The ethylene-0K)lefin mbber which is used according to the present invention may comprise any Cs-Cs owDlefm, for example propylene, 1-butene, 1-hexene, 1-octene or more than one CrCs a-oiefln. Preferably the ethylene-coiefin rubber is an ethylene-propylene rubber (EPR). Compared to other ethylene-Orolefin rubbers, EPRs have the advantage that they are more cost-effective than ethylene rubbers with higher Oroleflns and they can either be synthesised in the latter step(s) of a multistage process, where in the first 8tep(s) the random copolymer is synthesised or, alternatively, EPR's can be polymerised separately and mixed with the random copolymer and/or the HDPE component in a separate melt blending step. A further parameter to characterise the propylene copolymers used for the present invention is their content soluble In xylene at room temperature (XS content). For a random propylene copolymer it is preferred that the XS content is S12wt%, more preferably s 10 wt% and still more preferably S 8 wt%. Prefen-ed lower amounts for the XS contents are i 2 wt% and more preferably fc 3 wt% and still more preferably a 4wt%. The aforementioned XS contents are particularly preferred when the random propylene copolymer Is a binary propylene-ethylene random copolymer. For those embodiments of the present invention where the propyiene copoiymer comprises both a random propylene copolymer as well as an ethylene-a-olefin rubber It is preferred that the XS content of the propylene copolymer is from 15-50 wt%, more preferably from 15-40wt% and still more preferably from 15-35wt%. The aforementioned XS contents are particularly preferred when the random propylene copolymer is a binary propylene-ethylene random copolymer and the ethylene- Further, for those embodiments of the present invention where the propylene copolymer comprises both a random propylene copolymer as well as an ethylene-Or olefin rubber, it is preferred that amount of ethylene-cfrolefln rubber is from 8-35 wt% based on the total weight of the propylene copolymer, more preferably 10-30 wt%, still more preferably 12-25wt%. The aforementioned amounts of ethylene-a-olefin rubber are particularly prefenBd when the random propylene copolymer Is a binary propylene-ethylene random copolymer and the ethylene-otpolefln rubber is an ethylene-propylene rubber. For those embodiments of the present invention where the propylene copolymer comprises both a random propylene copolymer as well as an ethylene-ocrolefin rubber, it is prefen-ed that the propylene copolymer has an ethylene content of from 6 -30wt%, more preferably from 8-25wt%, still more preferabie from 9-20wt%. Again, the mentioned ranges are particulariy preferred when the random propylene copolymer is a binary propylene-ethylene random copolymer and the ethyiene-Oroiefin rubber is an ethylene-propylene rubber. For the propylene copolymer which is used in the present invention it is advantageous when its fluidity (expressed as MFR) is within a certain range. It is thus prefenred that the MFR of the propylene copolymer has an MFR (230 "C, 2.16 kg) of 0.5 to iOg/IOmin. Prefen-ed MFR values for the propylene copolymer are from 0.5-8 g/10 min, particularly prefenwl are 0.5 - 5 g/10 min. The main component of the polyolefin composition of the invention is a high density polyethylene (HOPE). Generally, the amount of HOPE in the polyolefin ownposition according to the invention ranges from 70 - 98 wt%, preferaWy 75 - 97 wt%, more iwferably 80 - 95 wt%. The HOPE which is used according to the present Invention may either be a homopolymer or an ethyiene-a-oiefin copoiymer. When an ethylene-a-oiefin copolymer Is used, the a-olefln preferably Is an Oroiefin having from 3 to 20 carbon atoms, more preferably from 4 to 10 carbon atoms, still more preferably from 4 to 6 carbon atoms. Examples of suitable a-olefins are propylene, 1-butene, 1-hexene and 1-octene. Preferred are 1-butene and 1-hexene, especially preferred Is 1-hexene. Generally, the amount of oroiefin contained in the ethylene-Orolefin copolymer in accordance with the present invention amounts to about 0.2 to 8 wt%, preferably 0.4 to 4 vrt%, and more preferably 0.6 to 3.0 wt%. An especially preferred a-olefin content Is in the range of from 0.6 to 2 wt%. The aforementioned concentration ranges are especially prefen-ed when the comonomer is 1-hexene. For 1-hexene an even more prefen-ed content is 0.7 -1.5 wt%, particularly 0.7 -1.0 wt%. Generally, the density of the HDPE of the polyolefin composition according to the present invention is Ijetween 930 to 965 kg/m3, preferably from 935 - 955 kg/m3 and more preferably firom 940 - 950 kg/m3. The aforementioned densities are especially prefen-ed when the comonomer Is 1-hexene. For 1-hexene as comonomer an even more prefen-ed density Is 942 - 950 kg/m3, particularly 945 - 950 kg/m3. The HDPE generally has an IVIFR (190°C/2.16kg) of from 0.2-15g/10mln, preferably of from 0.4-12 g/10 min and more preferably of from 0.5 -10 g/10 min, such as about 0.6 g/10 min. The HDPE preferably Is a mono-modal polymer with respect to the molecular weight distribution showing a rather nan-ow molecular weight distribution (MWD) IVUM„ of a 2 preferably from 2 to 8, more preferably 2 to 5, even more preferably 3.5 to 4.5, such as about 4. Generally, HDPE with a rather nanw MWD as outlined above and as used In the present Invention Is preferred for stretching, because narrow-MWD HDPE has a better stretchabiiity than HDPE with broad MWD (MJM„ of > 8, especially > 10). A direct result of this better stretchabiiity are better mechanical properties, i.e. the achievable maximum tenacity Is lower for fibres from broad-MWD HDPE. The (HOPE) to be employed in accordance with the present invention may be prepared using conventional polymerization techniques, In particular employing Ziegler-Natta catalysts. Suitable polymerization conditions and catalysts are known to the skilled person. Production of polymers Production of random propylene copolymers The polymerisation process for the production of the random propylene copolymers according to the invention may be a continuous process or a batch process utilising known methods and operating In liquid phase, optionally In the presence of an Inert diluent, or in gas phase or by mixed liquid-gas techniques. Accordingly, the random propylene copolymer may be produced by single- or multistage process polymerisation of propylene and o-olefin and/or ethylene such as bulk polymerisation, gas phase polymerisation, slurry polymerisation, solution polymerisation or combinations thereof using conventional catalysts. Preferably, the copolymer is made either in one or two loop reactor(s) or In a combination of loop and gas phase reactor. Those processes are well known to one skilled In the art. The process is preferably carried out in the presence of a stereospecific catalyst system. A suitable catalyst for the polymerisation of the propylene polymer is any stereospecific catalyst for propylene polymerisation which Is capable of polymerising and copolymerlsing propylene and a-olefin-comonomers at a temperature of 40 to HO'C and at a pressure from 10 to 100 bar. Ziegler Natta catalysts as well as metallocene catalysts are suitable catalysts. One skilled In the art is aware of the various possibiiities to produce random propylene copolymers and will simply find out a suitable procedure to produce suitable polymers which are used in the present Invention. As Ziegler-Natta catalyst any ordinary stereospecific Ziegler-Natta catalysts can be used. An essential component in those catalysts are solid catalyst components comprising a titanium compound having at least one titanium-halogen bond, an Intemal electron donor compound and a magnesium hallde in active form as a carrier for both the titanium component and the donor compound. The catalysts can contain - as internal electron donor - compounds selected from ethers, ketones, lactones, compounds containing N, P and/or S atoms and esters of mono and dlcarboxylic acids. Prefen-ed are aromatic esters lile benzoates or phthalates, e.g. ethyl benzoate or, diisobutylphtalat, or diethers lii A further essential component of the catalyst is a cocatalyst, an organoaluminium compound, such as an alkylaluminium compound, preferably triethyl-aluminium (TEAI) or tri-isobutyl-aluminium. Additionally, an external eiectnsn donor is generally used. Preferred are extemal donors according to the formula RxR'ySi(MeO)4.x.y, wherein R and R' are identical or different and are branched or cyclic aliphatic or aromatic hydrocarbon residues, and y and x independentty from each other are 0 or 1, provided that x + y are 1 or 2. Particularly preferred external donors are dicyclopentyldimethoxysilane and cyclohexyldimethoxymethylsiiane. To obtain the random propylene copolymer, it is preferred to use a polymerisation process based on a first polymerisation step in at least one siunv reactor and an optional second polymerisation step preferably comprising at least one gas phase reactor. Preferred siuny reactors are loop reactors. Prefen-ed reactor an-angements for producing the random propylene copolymer are a single loop reactor or two consecutive loop reactors or a loop reactor followed by a gas phase reactor. Before the catalyst system is used in the actual polymerisation process it is optionally pre-poiymerised with small amounts of a-olefins, preferably propylene, in order to enhance catalyst perfomnance and to improve the morphology of the end product. In the first polymerisation step of the process the optionally prepoiymerised catalyst system and a monomer feed comprised of propylene, and one or more of ethylene and/or CA-CS Orolefins is fed into a reactor. Preferably, the C4-C8 (M}leftn can be any one or mixtures of 1-butene, 4-methyl-1-pentene, 1-hexene or 1-octene. Particularly preferred are ethylene and 1-butene. The amount of comonomer in the feed can tie up to 40 wt%. Polymerisation can be canled out in the presence of the previously mentioned organoaluminium compound and an extemal donor compound at temperatures lower than 110 °C and pressures in the range of 10 to 100 bar, preferably 30 to 70 bar. The polymerisation is carried out in such conditions that 50 to 100 wt%, preferably 75 to 99 wt% of the end product is polymerised in the first reactor. Any metailocene catalyst capable of catalysing the fomnation of a propylene polymer can also be used. A suitable metailocene catalyst comprises a metallocene/activator reaction product, which is typically impregnated in a porous support at maximum internal pore volume. The catalyst complex comprises a ligand which is typically bridged, and a transition metal of group IVa ... Via , and an organoaluminium compound. The catalytic metal compound is typically a metal halide, e.g. ZrCi2. In the first polymerisation step a polymer is produced, in which the content of comonomer is in the range of up to 18.0 wt%, preferably up to 10 wt%. Hydrogen is added, when desired, into the first reactor for adjusting the molecular weight of polymer, as conventional. After the polymerisation is complete in the first reactor, the reaction medium is optionally transfemed into a second reactor, which can be a gas phase reactor. If the second reactor Is also a loop reactor, the same range of polymerisation conditions is available as for the first reactor. In the optional second reactor, 0 to 50 wt%, preferably 1 to 25 wt% of the final polymer is fomied. In the second reactor. If It is a gas phase reactor, the polymerisation can be carried out at a temperature of 60 to 90 °C and at a pressure higher than 5 bar, preferably higher than 10 bar. Optionally, propylene and oflier monomers can be added into the second reactor. Hydrogen can also be added Into the gas phase reactor, if desired. The precise control of the polymerisation conditions and reaction parameters Is within the state of the art. After the polymerisation in the first and the optional second reactor is finished, the polymer product Is recovered by conventional procedures. The resulting polymer particles may be pelietised In a conventional compounding extruder with various additives, which are generally used in thermoplastic polymer compositions, such as stabilisers, antioxidants, acid neutralising agents, ultraviolet absorbers, antistatic agents, etc. Production of ethylene-propylene rubber (EPR) An ethylene propylene rubber may be produced by lnown polymerisation processes such as solution, suspension and gas-phase polymerisation using conventional catalysts. Ziegier Natta catalysts as well as metallocene catalysts are suitable catalysts. A widely used process is the solution polymerisation. Ethylene, propylene and catalyst systems are polymerised In an excess of hydrocarbon solvent. Stabilisers and oils, If used, are added directly after polymerisation. The sdvent and unreacted monomers are then flashed off with hot water or steam, or with mechanical devolatilisation. The polymer, which Is in crumb form, is dried with dewatering in screens, mechanical presses or drying ovens. The crumb is fonned into wrapped bsAes or extruded into pellets. The suspension polymerisation process Is a modification of bulk polymerisatton. The monomers and catalyst system are injected Into the reactor filled with propylene. The polymerisation taices place immediately, fomiing crumbs of polymer that are not soluble in the propylene. Flashing off the propylene and comonomer completes the polymerisation process. The gas-phase polymerisation technology consists of one or more vertical fluidised beds. Monomers and nltnagen In gas form along with catalyst are fed to the reactor and solid product is removed periodically. Heat of reaction Is removed through the use of the circulating gas that also serves to fluidise the polymer bed. Solvents are not used, thereby eliminating the need for solvent stripping, washing and drying. The production of ethylene propylene rubber is also described in detail in e.g. US 3,300,459, US 5,919,877, EP 0 060 090 A1 and in a company publication by EniChem "DUTRAL, Ethylene-Propylene Elastomers", pages 1-4 (1991). Altematively, ethylene-propylene rubbers, which are commercially available and which fulfil the indicated requirements, can be used. The propylene copolymers according to the present invention can be conveniently produced by a) combining the random propylene copolymer in the form of powder or granules with ethylene-propylene mbber and optionally additional additives In a melt mixing device and melting, homogenising and pelletising the blend. Melt mixing devices suited for this process are discontinuous and continuous kneaders, twin screw extruders and single screw extruders with special mixing sections and co-kneaders. The residence time must be chosen such that a sufnciently high degree of homogenlsatlon Is achieved. b) subsequent polymerisation of the EPR after the polymerisation of the random propylene copolymer In a multistage process. Such a material is called random heterophasic copolymer (RAHECO). The latter is described In the following section: Production of RAHECO The production of a RAHECO begins with the production of a random propylene copolymer, which is already described above. Accordingly, for the production of a RAHECO it is prefen-ed to use a multistage polymerisation process which utilises, firstly, a reactor setup as outlined above, I.e. a polymerisation process based on a first polymerisation step in at least one slurry reactor and an optional second polymerisation step preferably comprising at least one gas phase reactor, for producing the random propylene copolymer, and, secondly, at least one additional polymerisation 8tep(s) in one or more gas phase reactors. I A prefen'ed reactor setup is a combination of bulk slunry loop Feactor(8} and gas phase reactor(s), particularty one loop reactor and one gas phase reactor (random copolymer In loop and EPR in gas phase) or two loop reactors and one or two gas phase reactors (random copolymer in loops and EPR in gas phases) or one loop and two gas phases (random copolymer in loop and EPR In gas phases or random copolymer In loop and 1 first gas phase and EPR in second gas phase) or one loop and three gas phases (random copolymer in loop and first gas phase and EPR in second and third gas phases). The produced random copolymer is transferred into a gas phase reactor, where EPR is produced, afterwards the product is optionally transfend Into a further gas phase reactor, where an optional further (or final) part of the EPR Is produced. The monomer feed (especially ethylene) to the gas phase reactor(s) where the EPR is produced is adjusted such that the final ethylene content of the RAHECO is between 6-30wt%. Further, the monomer feed (especially ethylene) to the gas phase reactor(s) where the EPR is produced is adjusted such that the final ethylene content of the EPR is from 20 - 80 wt%, preferably 30 - 70 wt%, more preferably 40 - 60 wt%. After the polymerisation is finished, the polymer product (RAHECO) is recovered by conventional procedures. The resulting polymer particles may be pelletised in a conventional compounding extruder with various additives, which are generally used in thermoplastic polymer compositions, such as stabilisers, antioxidants, acid neutralising agents, ultraviolet absorbers, antistatic agents. Production of IHDPE The ethylene homo- or copolymers which are used in accordance with the present invention are produced by a single- or multistage process by polymerisation of ethylene, optionally with CrCx Oroiefins, preferably 1-butene, 1-hexene or 1-octene, as comonomers for density regulation. The different stages can be carried out in liquid phase using suitable diluents and/or in gas phase at temperatures of 40-110 °C and pressures of 10 to 100 bar. The various possibilities for the production of HOPE and suitable catalysts therefor are described in detail In "Ethylene polymers, HOPE" in Encyclopedia of Polymer Science and Technology (© 2002 by John Wiley & Sons, Inc.), pages 385-391 and 401-404, the disclosure of which is incorporated herein by reference. Fibre preparation The polyolefin composition as defined above or below, typically In the form of pellets, is converted to fibres of the invention in a manner well i The term "fibre" as used herein Is meant to encompass fibres, stretch tapes, filaments and monofilaments alike. Particularly, when the term "fibre" is used alone, it is not to be understood so as to exclude any of the emb)odiments mentioned before. The fibres can preferably be produced via a film extnjsion process, such as cast film or blown film process, followed by film slitting to produce i.a. tapes, or via a direct extrusion process to produce filaments, preferably monofilaments. Before producing the fibres of the invention, the different polymer components are typically intimately mixed prior to extrusion as is well known in the art. According to one commonly used alternative, the polyolefin composition according to the invention can be extruded Into fibres, tapes or filaments, preferably monofilaments, using know filament extrusion process. One suitable process for producing the fibres of the invention Is described in "Fiber Technology" Hans A.Kra8Slg, JOrgen Lenz, Hennan F. Mark: ISBN: 0-8247-7097-8. In a second commonly used alternative, the polyolefin composition according to the invention are extruded Into a film which is subsequently cut Into fibres and tapes In a known manner. Both preparation methods are conventional and generally known in the production of fibres, tapes and filaments. As to the fibre preparation process wherein a film is first formed and then cut into fibres or tapes: The film may be prepared by any conventional film formation process including extrusion procedures, such as cast film or blown film extrusion, lamination processes or any combination thereof. The film may be a mono or multilayer film, e.g. a coextruded multilayer film. In case of a multilayer film, the film layers may comprise the same or different polymer composition, whereby at least one layer comprises the polyolefin composition according to the invention. Preferably, all layers of a multilayer film comprise, more preferably consist of, the same pdyplefin composition according to the invention. Particularly preferably the film is formed by blown film extrusion and in case of multilayered film structure by blown film coextrusion processes. Typically the polyolefin composition may be blown (co)extruded at a temperature, In the range IBCC to 240'C, and cooled by blowing gas (generally air) at a temperature of 10 to 50"C to provide a frost line height of 1 or 2 to 8 times the diameter of the die. The blow up ratio should generally be less than 6, less than 4, more preferably between 1.0 to 1.5, and even more preferably 1.0 to 1.2. The film may also be (co)extnjded to fomi first a bubble which is then collapsed and cooled, if necessary, and the obtained tubular film Is cut into fibres. Alternatively, the (co)extruded bubble may be collapsed and spilt into two film laminates. The fonned film Is then cut to fibres. Alternatively, fibres can be cut from a cast film that is produced by pnscedures well known in the field. In a very preferable embodiment of the invention fibres are in a stretched, i.e. oriented, form. In that case the fibres are preferably stretched uniaxlally, more preferably in machine direction (MD). Accordingly, in the first direct filament fomiation alternative, said fibres can be stretched to a desired draw ratio after extrusion to filaments. In the second fibre preparation alternative, wherein a film is first formed and cut to fibres, said film can be stretched before cutting to stretched fibres, e.g. tapes, or the film is first cut e.g. to tapes and then the fonned tapes are stretched to form the final fibres. Preferably the film is first cut e.g. into tapes which are then stretched to a desired draw ratio to form the final fibres. As to preparation of fibres by first forming a film and cutting it into fibres and tapes, reference can be made to the known Lenzing process (for stretching a film prior to cutting Into tapes) and Iso process (for cutting a film into tapes and stretching the formed tapes). As a prefen-ed embodiment thus stretched fibres are provided which are preferably in stretched. I.e. oriented, form, preferably in uniaxlally oriented form. Heat may typically be applied during the stretching, e.g. during in line stretching. The stretching ratio can be detemriined e.g. by the speed ratio of the godet rolls before and after the heating means in a manner known in the art. As also well known, the stretch and heat setting ratio's can be optimised and adapted depending on the dwnands of the end application. As heating means e.g. oven or hot plate can be used. Accordingly, the fibre preparation process preferably comprises a step of stretching extruded filaments, of stretching fibres/tapes cut from a film, or of stretching film prior to cutting into fibres/tapes, whereby the stretching is preferably effected in the machine direction (fD) in a draw ratio of at least 1:3. A preferable fibre preparation process thus comprises a step of extruding the polyolefin composition into - a fibre which is optionally stretched, preferably in MD, at least 3 times its original length, or - a film which is optionally stretched, preferably in MD, at least 3 times its original length and subsequently cut Into fibres, or which film is first cut into fibres which are optionally stretched, preferably in MD, at least 3 times their original length. More preferably, extruded fibres, fibres/tapes cut from a film or a film prior to cutting into fibres/tapes is/are stretched 3 to 10 times, its/their original length in the MD. The expressions "stretching 3 times its/their original length" and "drawn down to 3 times its/their original length" mean the same and can also be expressed as a "stretch ratio of at least 1:3" and, respectively, "draw ratio of at least 1:3", wherein "1" represents the original length of the film and "3" denotes that it has been stretched/drawn down to 3 times that original length. Prefen-ed films of the invention are stretched in a draw ratio of at least 1:4, more preferably in the range of 1:5 to 1:8, e.g. in a draw ratio of between 1:5 and 1:7. An effect of stretching, I.e. drawing, is that the thicitness of the film is simiiariy reduced. Thus a draw ratio of at least 1:3 means preferably that also the thickness of the film is at least three times less than the original thickness. The fibres can then be further processed to articles such as ropes, twines, nets, bags or textiles for technical and agricultural use. Measurement and determination methods MFR MFR's were determined according to ISO 1133 at 230'C witii a load of 2.16 kg for polypropylene and at 190 "C with a load of 2.16 kg for polyethylene. Comonomers Comonomer contents were measured with Fourier transfonn Infrared specfroscopy (FTIR) calibrated with "C-NIVIR. Density Detemnined according to ISO 1183 on compression moulded specimens, which were prepared at 220 "C in a cavity having the dimensions 240 x 240 x 4 mm according to the following procedure: - amount of resin is calculated using the cavity voiunve + additional 10% of the cavity volume. - melt time from room temperature to 220'C: 10 min - pressure was used in three steps (25/50/75 bar); 1 minute to reach 75 bar - press time at 220"C/75 bar: 5 min - cool down velocity IS'C / min Samples having the dimensions 80 x 10 x 4 mm were cut from the compression molded specimen. The samples were tested after 96 h. Xyiene solubies (XS) content: For the determination of the XS fraction, 2.0 g of polymer is dissolved in 250 ml of p-xylene at 135'C under stirring. After 30 ± 2 min the solution is allowed to cool for 5 min at ambient temperature and then allowed to settie for 30 min at 23 ± 0.5°C. The solution is filtered with a paper filter into two 100 ml flasks. The solution In the first 100 ml flask is evaporated in nitrogen flow and the residue is dried under vacuum at 90X until constant weight is reached. The xylene soluble (XS) fractton is then calculated using the following equation: XS[%] = (100miVo)/(moVi) wherein mo is tlie initial polymer amount [g], mi is tlie weiglit of the residue [g], vo is the initial volume [ml] and vi the volume of the analysed sample [ml]. Linear density Linear density of the stretched fibres was detemiined according to iSO 2060:1994, Option 1 at 23 "C and 50 % rel. humidity. Tensile properties Tensile properties (maximum force at break and eiongation at break) of the stretched fibres were detemiined according to EN 13895:2003 at 23 X and 50 % rel. humidity. Tenacity Tenacity at break was calculated by dividing the maximum force at break (in cN) by the linear density (in dtex). examples The following polymers were used in the examples VL4470 is a high density ethylene polymer, which Is commercially available from Borealis Polyoleflne GmbH, Austria. It has a density of 947 kg/m3, an MFR (190 X, 2.16 kg) of 0.60 g/10 min. VL4470 is a copolymer of ethylene with 1-hexene, produced with a Zlegler/Natta catalyst. Mw/Mn = 4. HB315BF Is a propylene homopolymer copolymer, which is commercially available from Borealis Polyoleflne GmbH, Austria. MFR (230 "C, 2.16 kg) is 2.3 g/10 mIn. RB307MO Is a propylene random copolymer, which is commercially availatrfe from Borealis Polyoleflne GmbH, Austria. MFR (230 'C, 2.16 kg) Is 1.5 g/10 mIn. Ethylene content is 4.8 wt%. SA233CF is a random heterophasic propylene-ethylene copolymer (RAHECO commercially available from Borealis Polyoleflne GmbH, Austria. The polymer has an MFR (230 "0/2.16 kg) of 0.8 g/10 min, a density of 905 kg/m» and an XS content of 28 wt%. It has an ethylene content of 15.5 wt%. Sample Preparation The stretch tape samples were prepared by using a state of the art pilot cast film stretch tape line. The extruder was equipped with a metering pump to ensure a constant output. Before film extrusion, the polymers were dry blended In the desired ratios. The water quenching tank, godets and oven used were ReifenhSuser components. The temperature profile of the extruder used was 225 "C, 230 °C and 235 °G. The die was kept at 235 "C. The film die had a 0.1 mm gap width. A 75 pm primary flim was extruded Into a water quench (30 °C) water bath. The take-off speed of the first godet roll was kept at 10 m/min. Tapes were slit and stretched in a hot air stretching oven with the below indicated stretch ratios, I.e. draw ratios. Annealing was done on the third godet stand. The three rolls of this godet were kept on a temperature of90, lOOandlOO-C. Selected film samples (silt tapes, unstretched) were examined under the light microscope and pictures taken therefrom are Included as Fig. 2-4. The pictures were taken with a Nikon D70 with a 60 mm AF Micro Nikkor. Fig. 2: VL4470 + 10% HB315BF Fig. 3: VL4470 + 10% RB307IVIO Fig. 4: VL4470 + 10% SA233CF Fig. 2-4 demonstrate, that films which are produced from blends of HOPE and propylene homopolymer show an unsatisfactory and inhomogeneous surface. Three test sample series with different draw ratios were prepared for each tested material: 1". Fibre sample series: tape samples were drawn 7 times their original lengti (draw ratio of 1:7) and 2"'. Fibre sample series: tape samples were drawn 8 times their original length (draw ratio of 1:8), 3"*. Fibre sample series: tape samples were drawn 9 times their original length (draw ratio of 1:9), unless othenAlse stated. The mechanical properties were tested according to the methods described above. The results of these tests are shown In tables 1-3. Fig. 1 shows a comparison of thie elongation/tenacity reiatlons for tiie basic fiigli density polyethyiene and Hie biends of tiie invention. Claims 1. A polyolefin composition comprising A) 2 - 30 wt% of a propylene copolymer which comprises a a) random propylene copolymer having a content of ethylene and/or C4-C8 ot-olefin of 0.5 to 12 wt% and optionally an b) ethylene-Opoiefin rubljer, B) 70 - 98 wt% of a high density polyethylene having a density of 930 to 965 kg/m3 and a MFR (190 °C/2.16 kg) of 0.3 to 20 g/10 min. 2. A polyolefin composition according to claim 1 wherein the random propylene copolymer has a content of ethylene and/or C4-C8 owjiefin of 0-5 to 12 wt%. 3. A polyolefin composition according to one of claims 1 or 2, characterised in that the comonomer in the random propylene copolymer is ethylene. 4. A polyolefin composition according to one of claims 1 to 3, characterised in that the propylene copolymer comprises an ethyiene-Orolefin rubber, wherein the d-oiefin is propylene. 5. A polyolefin composition according to one of claims 1 to 4, characterised in that propylene copolymer comprises an ethyiene-Oroiefin rubber and that the propylene copolymer has a XS content of 15 - 50 wt%. 6. A polyolefin composition according to one of claims 1 to 5, characterised in that propylene copolymer comprises an ethyiene-otolefin rubber and that the propylene copolymer has an ethylene content of from 6 to 30 wt%. 7. A polyolefin composition acconjing to one of claims 1 to 6, characterised in that the propylene copolymer has an MFR (230 "C, 2.16 kg) of 0.5 to 10 g/10 min. 8. A polyolefin composition according to one of claims 1 to 7, characterised in that the high density polyethylene is a homopolymer or a copolymer of ethylene and CrCx a-olefins. 9. A polyolefln composition according to one of ciaims 1 to 7, cfiaracterised In that the high density polyethylene has a density of 935 to 955 kg/m3. 10. A poiyoiefin composition according to one of claims 1 to 9, characterised in that the high density polyetiiylene has a MFR (190 °C/2.16 kg) of 0.2 to 15 g/10 min. 11. A poiyoiefin composition according to one of claims 1 to 10, characterised In that the high density polyethylene is obtained by polymerising ethylene and optionally one or more Cs-Cs Oroiefins In the presence of a Zlegler/Natta catalyst. 12. A poiyoiefin composition according to one of claims 1 to 11, characterised In that the high density polyethylene has a moldecular weight distribution (MWD) Mw/Mn of 2. 13. A drawn tape, fibre or filament comprising a poiyoiefin composition according to one of claims 1-12. 14. Tape, fibre or filament according to claim 12, characterised In that It has been drawn to at least 4 times its original length, preferably 6 to 10 times its original length. 15. An oriented film comprising a polyolefln composition according to one of claims 1- 12. 16. Oriented film according to claim 15, characterised in that it is oriented in machine direction only.

Full Text

NOVEL POLYOLEFIN COMPOSITIONS AND DRAWN TAPES, FIBRES AND FILAMENTS PRODUCED THEREFROM
The present invention relates to a novel poiyolefin composition which is suitable for producing drawn tapes, fibres and filaments which have improved mechanical properties.
Polyethylene is one of the materials used for the production of stretch tapes and monofilaments. The applications for tape and monofilaments are ranging from nets and ropes for marine, fishing and agricultural applications, geotextiles, nets for packaging and several other applications.
Higher drawability and tenacity will allow to develop new applications and will allow down gauging.
Improving the mechanical properties of polypropylene tapes and monofilaments by
blending in polyethylene Is well known and often applied.
However, improving the properties of polyethylene tapes and monofilaments by
blending in polypropylene is rather unknown. Some experience does exist in the form
of tapes produced from blends of polyethylene with a minor amount of propylene
homopolymer. The problem however Is, that in these blends the film appearance is
poor.
Object
It is the object of this invention to provide novel poiyolefin compositions, where drawn tapes, fibres and filaments made from these poiyolefin compositions have an Improved mechanical performance compared to tapes, fibres and filaments made from the basic ethylene polymer. Particularly, it Is desirable that the tapes, fibres and filaments either have an improved elongation at break or an improved tenacity compared to the respective fibre, tape or filament made from the baste ethylene polymer. It is particularly preferred, that at least the elongation at break is improved compared to the basic ethylene polymer. It is especially preferable that both the elongation at break and the tenacity are improved compared to the respective fibre, tape or filament made from the basic ethylene polymer.

The above mentioned problem is solved by blending a small amount of a propylene copolymer with a high density polyethylene. Tapes and monofilaments made from such a composition have a higher drawability and an improved tenacity-elongation balance.
More particularly, the aforementioned object is achieved with a polyolefin composition comprising
A) 2 - 30 wt% of a propylene copolymer which comprises a
a) random propylene copolymer having a content of ethylene and/or C4-C6 a-olefin of 0.5 to 12 wt% and optionally an
b) ethylene-cwiefin rubber,
B) 70 - 98 wt% of a high density polyethylene having a density of 930 to 965 kg/m3 and
a MFR (190 °C/2.16 kg) of 0.3 to 20 g/10 min.
Generally, the amount of propylene copolymer in the polyolefin composition of the invention ranges from 2-30 wt%, preferably from 3-25 wt% and more preferably from 5-20 wt%. A necessary component of the propylene copolymer is a random propylene copolymer.
A random propylene copolymer according to the present invention is a random propylen-copolymer produced by statistical Insertion of units of ethylene and/or C4-C8 Orolefins.
As comonomers the random propylene copolymer according to the present invention may contain ethylene and/or one or more C4-CS Orolefins. Suitable Oroiefins may be linear or branched. Preferred ct-oiefins are 1-butene, 1-hexene, 1-octene and 4-methyl-1-pentene. Ethylene and 1-butene are especially prefenred as comonomers.
According to the invention, it is prefend that the random propylene copolymer either is a binary copolymer of propylene with ethylene or a binary copolymer of propylene with 1-butene or a terpolymer of propylene with ethylene and 1-butene.
According to the present Invention the used random copolymer preferably has a comonomer content of 0.5 to 12 wt%, preferably 1 to 11 wt%. For a binary copolymer of propylene with ethylene the preferred comonomer content is 0.5 to 8 wt%, more preferably 1 to 7 wt%, even more preferably 2 to 6 wt%.

For a binary copolymer of propylene with 1-butene the preferred comonomer content is 0.5 to 10 wt%, more preferably 1 to 9, even more preferably 2 to 8 wt%. For a terpolymer of propylene with ethylene and 1-butene the total comonomer content preferably is 0.5 to 16wt%, more preferably 1 to 13wt%, even more preferably 2 to 10 wt%. For a terpolymer the ethylene content is preferably smaller than the 1-butene content and the prefenred ratio of ethylene content to 1-butene content Is s 0.5, more preferable s 0.3. Further, for a terpolymer of propylene with ethylene and 1-butene the prefen-ed content of ethylene Is from 0.3 - 3 wt% and tiie prefend 1-butene content is from 0.7- 15wt%.
According to an optional embodiment the propylene copolymer used in the present Invention comprises an ethyiene-Orolefin rubber.
It has surprisingly been found that compositions where the propylene copolymer comprises a random propylene copolymer and an ethylene-CK)lefln rubber also show a level of mechanical properties which - on average - are improved compared to compositions containing no modifier or a propylene homopolymer as modifier.
The ethylene-0K)lefin mbber which is used according to the present invention may comprise any Cs-Cs owDlefm, for example propylene, 1-butene, 1-hexene, 1-octene or more than one CrCs a-oiefln.
Preferably the ethylene-coiefin rubber is an ethylene-propylene rubber (EPR). Compared to other ethylene-Orolefin rubbers, EPRs have the advantage that they are more cost-effective than ethylene rubbers with higher Oroleflns and they can either be synthesised in the latter step(s) of a multistage process, where in the first 8tep(s) the random copolymer is synthesised or, alternatively, EPR's can be polymerised separately and mixed with the random copolymer and/or the HDPE component in a separate melt blending step.
A further parameter to characterise the propylene copolymers used for the present invention is their content soluble In xylene at room temperature (XS content).
For a random propylene copolymer it is preferred that the XS content is S12wt%, more preferably s 10 wt% and still more preferably S 8 wt%. Prefen-ed lower amounts for the XS contents are i 2 wt% and more preferably fc 3 wt% and still more preferably a 4wt%. The aforementioned XS contents are particularly preferred when the random propylene copolymer Is a binary propylene-ethylene random copolymer.

For those embodiments of the present invention where the propyiene copoiymer comprises both a random propylene copolymer as well as an ethylene-a-olefin rubber It is preferred that the XS content of the propylene copolymer is from 15-50 wt%, more preferably from 15-40wt% and still more preferably from 15-35wt%. The aforementioned XS contents are particularly preferred when the random propylene copolymer is a binary propylene-ethylene random copolymer and the ethylene- Further, for those embodiments of the present invention where the propylene copolymer comprises both a random propylene copolymer as well as an ethylene-Or olefin rubber, it is preferred that amount of ethylene-cfrolefln rubber is from 8-35 wt% based on the total weight of the propylene copolymer, more preferably 10-30 wt%, still more preferably 12-25wt%. The aforementioned amounts of ethylene-a-olefin rubber are particularly prefenBd when the random propylene copolymer Is a binary propylene-ethylene random copolymer and the ethylene-otpolefln rubber is an ethylene-propylene rubber.
For those embodiments of the present invention where the propylene copolymer comprises both a random propylene copolymer as well as an ethylene-ocrolefin rubber, it is prefen-ed that the propylene copolymer has an ethylene content of from 6 -30wt%, more preferably from 8-25wt%, still more preferabie from 9-20wt%. Again, the mentioned ranges are particulariy preferred when the random propylene copolymer is a binary propylene-ethylene random copolymer and the ethyiene-Oroiefin rubber is an ethylene-propylene rubber.
For the propylene copolymer which is used in the present invention it is advantageous when its fluidity (expressed as MFR) is within a certain range. It is thus prefenred that the MFR of the propylene copolymer has an MFR (230 "C, 2.16 kg) of 0.5 to iOg/IOmin. Prefen-ed MFR values for the propylene copolymer are from 0.5-8 g/10 min, particularly prefenwl are 0.5 - 5 g/10 min.
The main component of the polyolefin composition of the invention is a high density polyethylene (HOPE).
Generally, the amount of HOPE in the polyolefin ownposition according to the invention ranges from 70 - 98 wt%, preferaWy 75 - 97 wt%, more iwferably 80 - 95 wt%.

The HOPE which is used according to the present Invention may either be a homopolymer or an ethyiene-a-oiefin copoiymer. When an ethylene-a-oiefin copolymer Is used, the a-olefln preferably Is an Oroiefin having from 3 to 20 carbon atoms, more preferably from 4 to 10 carbon atoms, still more preferably from 4 to 6 carbon atoms. Examples of suitable a-olefins are propylene, 1-butene, 1-hexene and 1-octene. Preferred are 1-butene and 1-hexene, especially preferred Is 1-hexene.
Generally, the amount of oroiefin contained in the ethylene-Orolefin copolymer in accordance with the present invention amounts to about 0.2 to 8 wt%, preferably 0.4 to 4 vrt%, and more preferably 0.6 to 3.0 wt%. An especially preferred a-olefin content Is in the range of from 0.6 to 2 wt%. The aforementioned concentration ranges are especially prefen-ed when the comonomer is 1-hexene. For 1-hexene an even more prefen-ed content is 0.7 -1.5 wt%, particularly 0.7 -1.0 wt%.
Generally, the density of the HDPE of the polyolefin composition according to the present invention is Ijetween 930 to 965 kg/m3, preferably from 935 - 955 kg/m3 and more preferably firom 940 - 950 kg/m3. The aforementioned densities are especially prefen-ed when the comonomer Is 1-hexene. For 1-hexene as comonomer an even more prefen-ed density Is 942 - 950 kg/m3, particularly 945 - 950 kg/m3.
The HDPE generally has an IVIFR (190°C/2.16kg) of from 0.2-15g/10mln, preferably of from 0.4-12 g/10 min and more preferably of from 0.5 -10 g/10 min, such as about 0.6 g/10 min.
The HDPE preferably Is a mono-modal polymer with respect to the molecular weight distribution showing a rather nan-ow molecular weight distribution (MWD) IVUM„ of a 2 preferably from 2 to 8, more preferably 2 to 5, even more preferably 3.5 to 4.5, such as about 4.
Generally, HDPE with a rather nanw MWD as outlined above and as used In the present Invention Is preferred for stretching, because narrow-MWD HDPE has a better stretchabiiity than HDPE with broad MWD (MJM„ of > 8, especially > 10). A direct result of this better stretchabiiity are better mechanical properties, i.e. the achievable maximum tenacity Is lower for fibres from broad-MWD HDPE.

The (HOPE) to be employed in accordance with the present invention may be prepared using conventional polymerization techniques, In particular employing Ziegler-Natta catalysts. Suitable polymerization conditions and catalysts are known to the skilled person.
Production of polymers
Production of random propylene copolymers
The polymerisation process for the production of the random propylene copolymers according to the invention may be a continuous process or a batch process utilising known methods and operating In liquid phase, optionally In the presence of an Inert diluent, or in gas phase or by mixed liquid-gas techniques.
Accordingly, the random propylene copolymer may be produced by single- or multistage process polymerisation of propylene and o-olefin and/or ethylene such as bulk polymerisation, gas phase polymerisation, slurry polymerisation, solution polymerisation or combinations thereof using conventional catalysts. Preferably, the copolymer is made either in one or two loop reactor(s) or In a combination of loop and gas phase reactor. Those processes are well known to one skilled In the art. The process is preferably carried out in the presence of a stereospecific catalyst system.
A suitable catalyst for the polymerisation of the propylene polymer is any stereospecific catalyst for propylene polymerisation which Is capable of polymerising and copolymerlsing propylene and a-olefin-comonomers at a temperature of 40 to HO'C and at a pressure from 10 to 100 bar. Ziegler Natta catalysts as well as metallocene catalysts are suitable catalysts.
One skilled In the art is aware of the various possibiiities to produce random propylene copolymers and will simply find out a suitable procedure to produce suitable polymers which are used in the present Invention.
As Ziegler-Natta catalyst any ordinary stereospecific Ziegler-Natta catalysts can be used. An essential component in those catalysts are solid catalyst components comprising a titanium compound having at least one titanium-halogen bond, an Intemal electron donor compound and a magnesium hallde in active form as a carrier for both the titanium component and the donor compound. The catalysts can contain - as

internal electron donor - compounds selected from ethers, ketones, lactones, compounds containing N, P and/or S atoms and esters of mono and dlcarboxylic acids. Prefen-ed are aromatic esters lile benzoates or phthalates, e.g. ethyl benzoate or, diisobutylphtalat, or diethers lii A further essential component of the catalyst is a cocatalyst, an organoaluminium compound, such as an alkylaluminium compound, preferably triethyl-aluminium (TEAI) or tri-isobutyl-aluminium.
Additionally, an external eiectnsn donor is generally used. Preferred are extemal donors according to the formula
RxR'ySi(MeO)4.x.y, wherein R and R' are identical or different and are branched or cyclic aliphatic or aromatic hydrocarbon residues, and y and x independentty from each other are 0 or 1, provided that x + y are 1 or 2.
Particularly preferred external donors are dicyclopentyldimethoxysilane and cyclohexyldimethoxymethylsiiane.
To obtain the random propylene copolymer, it is preferred to use a polymerisation process based on a first polymerisation step in at least one siunv reactor and an optional second polymerisation step preferably comprising at least one gas phase reactor. Preferred siuny reactors are loop reactors.
Prefen-ed reactor an-angements for producing the random propylene copolymer are a single loop reactor or two consecutive loop reactors or a loop reactor followed by a gas phase reactor.
Before the catalyst system is used in the actual polymerisation process it is optionally pre-poiymerised with small amounts of a-olefins, preferably propylene, in order to enhance catalyst perfomnance and to improve the morphology of the end product.
In the first polymerisation step of the process the optionally prepoiymerised catalyst system and a monomer feed comprised of propylene, and one or more of ethylene and/or CA-CS Orolefins is fed into a reactor. Preferably, the C4-C8 (M}leftn can be any one or mixtures of 1-butene, 4-methyl-1-pentene, 1-hexene or 1-octene. Particularly

preferred are ethylene and 1-butene. The amount of comonomer in the feed can tie up to 40 wt%.
Polymerisation can be canled out in the presence of the previously mentioned organoaluminium compound and an extemal donor compound at temperatures lower than 110 °C and pressures in the range of 10 to 100 bar, preferably 30 to 70 bar. The polymerisation is carried out in such conditions that 50 to 100 wt%, preferably 75 to 99 wt% of the end product is polymerised in the first reactor.
Any metailocene catalyst capable of catalysing the fomnation of a propylene polymer can also be used. A suitable metailocene catalyst comprises a metallocene/activator reaction product, which is typically impregnated in a porous support at maximum internal pore volume. The catalyst complex comprises a ligand which is typically bridged, and a transition metal of group IVa ... Via , and an organoaluminium compound. The catalytic metal compound is typically a metal halide, e.g. ZrCi2.
In the first polymerisation step a polymer is produced, in which the content of comonomer is in the range of up to 18.0 wt%, preferably up to 10 wt%. Hydrogen is added, when desired, into the first reactor for adjusting the molecular weight of polymer, as conventional.
After the polymerisation is complete in the first reactor, the reaction medium is optionally transfemed into a second reactor, which can be a gas phase reactor. If the second reactor Is also a loop reactor, the same range of polymerisation conditions is available as for the first reactor.
In the optional second reactor, 0 to 50 wt%, preferably 1 to 25 wt% of the final polymer is fomied. In the second reactor. If It is a gas phase reactor, the polymerisation can be carried out at a temperature of 60 to 90 °C and at a pressure higher than 5 bar, preferably higher than 10 bar. Optionally, propylene and oflier monomers can be added into the second reactor. Hydrogen can also be added Into the gas phase reactor, if desired.

The precise control of the polymerisation conditions and reaction parameters Is within the state of the art. After the polymerisation in the first and the optional second reactor is finished, the polymer product Is recovered by conventional procedures.
The resulting polymer particles may be pelietised In a conventional compounding extruder with various additives, which are generally used in thermoplastic polymer compositions, such as stabilisers, antioxidants, acid neutralising agents, ultraviolet absorbers, antistatic agents, etc.
Production of ethylene-propylene rubber (EPR)
An ethylene propylene rubber may be produced by lnown polymerisation processes such as solution, suspension and gas-phase polymerisation using conventional catalysts. Ziegier Natta catalysts as well as metallocene catalysts are suitable catalysts.
A widely used process is the solution polymerisation. Ethylene, propylene and catalyst systems are polymerised In an excess of hydrocarbon solvent. Stabilisers and oils, If used, are added directly after polymerisation. The sdvent and unreacted monomers are then flashed off with hot water or steam, or with mechanical devolatilisation. The polymer, which Is in crumb form, is dried with dewatering in screens, mechanical presses or drying ovens. The crumb is fonned into wrapped bsAes or extruded into pellets.
The suspension polymerisation process Is a modification of bulk polymerisatton. The monomers and catalyst system are injected Into the reactor filled with propylene. The polymerisation taices place immediately, fomiing crumbs of polymer that are not soluble in the propylene. Flashing off the propylene and comonomer completes the polymerisation process.
The gas-phase polymerisation technology consists of one or more vertical fluidised beds. Monomers and nltnagen In gas form along with catalyst are fed to the reactor and solid product is removed periodically. Heat of reaction Is removed through the use of the circulating gas that also serves to fluidise the polymer bed. Solvents are not used, thereby eliminating the need for solvent stripping, washing and drying.

The production of ethylene propylene rubber is also described in detail in e.g. US 3,300,459, US 5,919,877, EP 0 060 090 A1 and in a company publication by EniChem "DUTRAL, Ethylene-Propylene Elastomers", pages 1-4 (1991).
Altematively, ethylene-propylene rubbers, which are commercially available and which fulfil the indicated requirements, can be used.
The propylene copolymers according to the present invention can be conveniently produced by
a) combining the random propylene copolymer in the form of powder or granules with ethylene-propylene mbber and optionally additional additives In a melt mixing device and melting, homogenising and pelletising the blend. Melt mixing devices suited for this process are discontinuous and continuous kneaders, twin screw extruders and single screw extruders with special mixing sections and co-kneaders. The residence time must be chosen such that a sufnciently high degree of homogenlsatlon Is achieved.
b) subsequent polymerisation of the EPR after the polymerisation of the random propylene copolymer In a multistage process. Such a material is called random heterophasic copolymer (RAHECO). The latter is described In the following section:
Production of RAHECO
The production of a RAHECO begins with the production of a random propylene copolymer, which is already described above.
Accordingly, for the production of a RAHECO it is prefen-ed to use a multistage polymerisation process which utilises, firstly, a reactor setup as outlined above, I.e. a polymerisation process based on a first polymerisation step in at least one slurry reactor and an optional second polymerisation step preferably comprising at least one gas phase reactor, for producing the random propylene copolymer, and, secondly, at least one additional polymerisation 8tep(s) in one or more gas phase reactors.
I A prefen'ed reactor setup is a combination of bulk slunry loop Feactor(8} and gas phase reactor(s), particularty one loop reactor and one gas phase reactor (random copolymer In loop and EPR in gas phase) or two loop reactors and one or two gas phase reactors (random copolymer in loops and EPR in gas phases) or one loop and two gas phases (random copolymer in loop and EPR In gas phases or random copolymer In loop and
1 first gas phase and EPR in second gas phase) or one loop and three gas phases

(random copolymer in loop and first gas phase and EPR in second and third gas phases).
The produced random copolymer is transferred into a gas phase reactor, where EPR is produced, afterwards the product is optionally transfend Into a further gas phase reactor, where an optional further (or final) part of the EPR Is produced.
The monomer feed (especially ethylene) to the gas phase reactor(s) where the EPR is produced is adjusted such that the final ethylene content of the RAHECO is between 6-30wt%. Further, the monomer feed (especially ethylene) to the gas phase reactor(s) where the EPR is produced is adjusted such that the final ethylene content of the EPR is from 20 - 80 wt%, preferably 30 - 70 wt%, more preferably 40 - 60 wt%.
After the polymerisation is finished, the polymer product (RAHECO) is recovered by conventional procedures. The resulting polymer particles may be pelletised in a conventional compounding extruder with various additives, which are generally used in thermoplastic polymer compositions, such as stabilisers, antioxidants, acid neutralising agents, ultraviolet absorbers, antistatic agents.
Production of IHDPE
The ethylene homo- or copolymers which are used in accordance with the present invention are produced by a single- or multistage process by polymerisation of ethylene, optionally with CrCx Oroiefins, preferably 1-butene, 1-hexene or 1-octene, as comonomers for density regulation. The different stages can be carried out in liquid phase using suitable diluents and/or in gas phase at temperatures of 40-110 °C and pressures of 10 to 100 bar. The various possibilities for the production of HOPE and suitable catalysts therefor are described in detail In "Ethylene polymers, HOPE" in Encyclopedia of Polymer Science and Technology (© 2002 by John Wiley & Sons, Inc.), pages 385-391 and 401-404, the disclosure of which is incorporated herein by reference.
Fibre preparation
The polyolefin composition as defined above or below, typically In the form of pellets, is converted to fibres of the invention in a manner well i
The term "fibre" as used herein Is meant to encompass fibres, stretch tapes, filaments and monofilaments alike. Particularly, when the term "fibre" is used alone, it is not to be understood so as to exclude any of the emb)odiments mentioned before.
The fibres can preferably be produced via a film extnjsion process, such as cast film or blown film process, followed by film slitting to produce i.a. tapes, or via a direct extrusion process to produce filaments, preferably monofilaments.
Before producing the fibres of the invention, the different polymer components are typically intimately mixed prior to extrusion as is well known in the art.
According to one commonly used alternative, the polyolefin composition according to the invention can be extruded Into fibres, tapes or filaments, preferably monofilaments, using know filament extrusion process. One suitable process for producing the fibres of the invention Is described in "Fiber Technology" Hans A.Kra8Slg, JOrgen Lenz, Hennan F. Mark: ISBN: 0-8247-7097-8.
In a second commonly used alternative, the polyolefin composition according to the invention are extruded Into a film which is subsequently cut Into fibres and tapes In a known manner. Both preparation methods are conventional and generally known in the production of fibres, tapes and filaments.
As to the fibre preparation process wherein a film is first formed and then cut into fibres or tapes: The film may be prepared by any conventional film formation process including extrusion procedures, such as cast film or blown film extrusion, lamination processes or any combination thereof. The film may be a mono or multilayer film, e.g. a coextruded multilayer film. In case of a multilayer film, the film layers may comprise the same or different polymer composition, whereby at least one layer comprises the polyolefin composition according to the invention. Preferably, all layers of a multilayer film comprise, more preferably consist of, the same pdyplefin composition according to the invention.
Particularly preferably the film is formed by blown film extrusion and in case of multilayered film structure by blown film coextrusion processes. Typically the polyolefin composition may be blown (co)extruded at a temperature, In the range IBCC to 240'C,

and cooled by blowing gas (generally air) at a temperature of 10 to 50"C to provide a frost line height of 1 or 2 to 8 times the diameter of the die. The blow up ratio should generally be less than 6, less than 4, more preferably between 1.0 to 1.5, and even more preferably 1.0 to 1.2.
The film may also be (co)extnjded to fomi first a bubble which is then collapsed and cooled, if necessary, and the obtained tubular film Is cut into fibres. Alternatively, the (co)extruded bubble may be collapsed and spilt into two film laminates. The fonned film Is then cut to fibres.
Alternatively, fibres can be cut from a cast film that is produced by pnscedures well known in the field.
In a very preferable embodiment of the invention fibres are in a stretched, i.e. oriented, form. In that case the fibres are preferably stretched uniaxlally, more preferably in machine direction (MD). Accordingly, in the first direct filament fomiation alternative, said fibres can be stretched to a desired draw ratio after extrusion to filaments. In the second fibre preparation alternative, wherein a film is first formed and cut to fibres, said film can be stretched before cutting to stretched fibres, e.g. tapes, or the film is first cut e.g. to tapes and then the fonned tapes are stretched to form the final fibres. Preferably the film is first cut e.g. into tapes which are then stretched to a desired draw ratio to form the final fibres. As to preparation of fibres by first forming a film and cutting it into fibres and tapes, reference can be made to the known Lenzing process (for stretching a film prior to cutting Into tapes) and Iso process (for cutting a film into tapes and stretching the formed tapes).
As a prefen-ed embodiment thus stretched fibres are provided which are preferably in stretched. I.e. oriented, form, preferably in uniaxlally oriented form.
Heat may typically be applied during the stretching, e.g. during in line stretching. The stretching ratio can be detemriined e.g. by the speed ratio of the godet rolls before and after the heating means in a manner known in the art. As also well known, the stretch and heat setting ratio's can be optimised and adapted depending on the dwnands of the end application. As heating means e.g. oven or hot plate can be used.

Accordingly, the fibre preparation process preferably comprises a step of stretching extruded filaments, of stretching fibres/tapes cut from a film, or of stretching film prior to cutting into fibres/tapes, whereby the stretching is preferably effected in the machine direction (fD) in a draw ratio of at least 1:3.
A preferable fibre preparation process thus comprises a step of extruding the polyolefin composition into
- a fibre which is optionally stretched, preferably in MD, at least 3 times its original length, or
- a film which is optionally stretched, preferably in MD, at least 3 times its original length and subsequently cut Into fibres, or which film is first cut into fibres which are optionally stretched, preferably in MD, at least 3 times their original length.
More preferably, extruded fibres, fibres/tapes cut from a film or a film prior to cutting into fibres/tapes is/are stretched 3 to 10 times, its/their original length in the MD. The expressions "stretching 3 times its/their original length" and "drawn down to 3 times its/their original length" mean the same and can also be expressed as a "stretch ratio of at least 1:3" and, respectively, "draw ratio of at least 1:3", wherein "1" represents the original length of the film and "3" denotes that it has been stretched/drawn down to 3 times that original length. Prefen-ed films of the invention are stretched in a draw ratio of at least 1:4, more preferably in the range of 1:5 to 1:8, e.g. in a draw ratio of between 1:5 and 1:7. An effect of stretching, I.e. drawing, is that the thicitness of the film is simiiariy reduced. Thus a draw ratio of at least 1:3 means preferably that also the thickness of the film is at least three times less than the original thickness.
The fibres can then be further processed to articles such as ropes, twines, nets, bags or textiles for technical and agricultural use.

Measurement and determination methods MFR
MFR's were determined according to ISO 1133 at 230'C witii a load of 2.16 kg for polypropylene and at 190 "C with a load of 2.16 kg for polyethylene.
Comonomers
Comonomer contents were measured with Fourier transfonn Infrared specfroscopy (FTIR) calibrated with "C-NIVIR.
Density
Detemnined according to ISO 1183 on compression moulded specimens, which were prepared at 220 "C in a cavity having the dimensions 240 x 240 x 4 mm according to the following procedure:
- amount of resin is calculated using the cavity voiunve + additional 10% of the cavity volume.
- melt time from room temperature to 220'C: 10 min
- pressure was used in three steps (25/50/75 bar); 1 minute to reach 75 bar
- press time at 220"C/75 bar: 5 min
- cool down velocity IS'C / min
Samples having the dimensions 80 x 10 x 4 mm were cut from the compression
molded specimen.
The samples were tested after 96 h.
Xyiene solubies (XS) content:
For the determination of the XS fraction, 2.0 g of polymer is dissolved in 250 ml of p-xylene at 135'C under stirring. After 30 ± 2 min the solution is allowed to cool for 5 min at ambient temperature and then allowed to settie for 30 min at 23 ± 0.5°C. The solution is filtered with a paper filter into two 100 ml flasks. The solution In the first 100 ml flask is evaporated in nitrogen flow and the residue is dried under vacuum at 90X until constant weight is reached. The xylene soluble (XS) fractton is then calculated using the following equation:
XS[%] = (100miVo)/(moVi)

wherein mo is tlie initial polymer amount [g], mi is tlie weiglit of the residue [g], vo is the initial volume [ml] and vi the volume of the analysed sample [ml].

Linear density
Linear density of the stretched fibres was detemiined according to iSO 2060:1994, Option 1 at 23 "C and 50 % rel. humidity.
Tensile properties
Tensile properties (maximum force at break and eiongation at break) of the stretched fibres were detemiined according to EN 13895:2003 at 23 X and 50 % rel. humidity.
Tenacity
Tenacity at break was calculated by dividing the maximum force at break (in cN) by the linear density (in dtex).

examples
The following polymers were used in the examples
VL4470 is a high density ethylene polymer, which Is commercially available from Borealis Polyoleflne GmbH, Austria. It has a density of 947 kg/m3, an MFR (190 X, 2.16 kg) of 0.60 g/10 min. VL4470 is a copolymer of ethylene with 1-hexene, produced with a Zlegler/Natta catalyst. Mw/Mn = 4.
HB315BF Is a propylene homopolymer copolymer, which is commercially available from Borealis Polyoleflne GmbH, Austria. MFR (230 "C, 2.16 kg) is 2.3 g/10 mIn.
RB307MO Is a propylene random copolymer, which is commercially availatrfe from Borealis Polyoleflne GmbH, Austria. MFR (230 'C, 2.16 kg) Is 1.5 g/10 mIn. Ethylene content is 4.8 wt%.
SA233CF is a random heterophasic propylene-ethylene copolymer (RAHECO commercially available from Borealis Polyoleflne GmbH, Austria. The polymer has an MFR (230 "0/2.16 kg) of 0.8 g/10 min, a density of 905 kg/m» and an XS content of 28 wt%. It has an ethylene content of 15.5 wt%.
Sample Preparation
The stretch tape samples were prepared by using a state of the art pilot cast film stretch tape line. The extruder was equipped with a metering pump to ensure a constant output. Before film extrusion, the polymers were dry blended In the desired ratios. The water quenching tank, godets and oven used were ReifenhSuser components. The temperature profile of the extruder used was 225 "C, 230 °C and 235 °G. The die was kept at 235 "C. The film die had a 0.1 mm gap width. A 75 pm primary flim was extruded Into a water quench (30 °C) water bath. The take-off speed of the first godet roll was kept at 10 m/min. Tapes were slit and stretched in a hot air stretching oven with the below indicated stretch ratios, I.e. draw ratios. Annealing was done on the third godet stand. The three rolls of this godet were kept on a temperature of90, lOOandlOO-C.

Selected film samples (silt tapes, unstretched) were examined under the light microscope and pictures taken therefrom are Included as Fig. 2-4. The pictures were taken with a Nikon D70 with a 60 mm AF Micro Nikkor. Fig. 2: VL4470 + 10% HB315BF Fig. 3: VL4470 + 10% RB307IVIO Fig. 4: VL4470 + 10% SA233CF
Fig. 2-4 demonstrate, that films which are produced from blends of HOPE and propylene homopolymer show an unsatisfactory and inhomogeneous surface.
Three test sample series with different draw ratios were prepared for each tested
material:
1". Fibre sample series: tape samples were drawn 7 times their original lengti (draw
ratio of 1:7) and
2"'. Fibre sample series: tape samples were drawn 8 times their original length (draw
ratio of 1:8),
3"*. Fibre sample series: tape samples were drawn 9 times their original length (draw
ratio of 1:9), unless othenAlse stated.
The mechanical properties were tested according to the methods described above. The results of these tests are shown In tables 1-3.

Fig. 1 shows a comparison of thie elongation/tenacity reiatlons for tiie basic fiigli density polyethyiene and Hie biends of tiie invention.

Claims
1. A polyolefin composition comprising
A) 2 - 30 wt% of a propylene copolymer which comprises a
a) random propylene copolymer having a content of ethylene and/or C4-C8 ot-olefin of 0.5 to 12 wt% and optionally an
b) ethylene-Opoiefin rubljer,
B) 70 - 98 wt% of a high density polyethylene having a density of 930 to 965 kg/m3 and
a MFR (190 °C/2.16 kg) of 0.3 to 20 g/10 min.
2. A polyolefin composition according to claim 1 wherein the random propylene copolymer has a content of ethylene and/or C4-C8 owjiefin of 0-5 to 12 wt%.
3. A polyolefin composition according to one of claims 1 or 2, characterised in that the comonomer in the random propylene copolymer is ethylene.
4. A polyolefin composition according to one of claims 1 to 3, characterised in that the propylene copolymer comprises an ethyiene-Orolefin rubber, wherein the d-oiefin is propylene.
5. A polyolefin composition according to one of claims 1 to 4, characterised in that propylene copolymer comprises an ethyiene-Oroiefin rubber and that the propylene copolymer has a XS content of 15 - 50 wt%.
6. A polyolefin composition according to one of claims 1 to 5, characterised in that propylene copolymer comprises an ethyiene-otolefin rubber and that the propylene copolymer has an ethylene content of from 6 to 30 wt%.
7. A polyolefin composition acconjing to one of claims 1 to 6, characterised in that the propylene copolymer has an MFR (230 "C, 2.16 kg) of 0.5 to 10 g/10 min.
8. A polyolefin composition according to one of claims 1 to 7, characterised in that the high density polyethylene is a homopolymer or a copolymer of ethylene and CrCx a-olefins.

9. A polyolefln composition according to one of ciaims 1 to 7, cfiaracterised In that the
high density polyethylene has a density of 935 to 955 kg/m3.
10. A poiyoiefin composition according to one of claims 1 to 9, characterised in that the
high density polyetiiylene has a MFR (190 °C/2.16 kg) of 0.2 to 15 g/10 min.
11. A poiyoiefin composition according to one of claims 1 to 10, characterised In that
the high density polyethylene is obtained by polymerising ethylene and optionally one
or more Cs-Cs Oroiefins In the presence of a Zlegler/Natta catalyst.
12. A poiyoiefin composition according to one of claims 1 to 11, characterised In that
the high density polyethylene has a moldecular weight distribution (MWD) Mw/Mn of 2.
13. A drawn tape, fibre or filament comprising a poiyoiefin composition according to
one of claims 1-12.
14. Tape, fibre or filament according to claim 12, characterised In that It has been
drawn to at least 4 times its original length, preferably 6 to 10 times its original length.
15. An oriented film comprising a polyolefln composition according to one of claims 1-
12.
16. Oriented film according to claim 15, characterised in that it is oriented in machine
direction only.

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Patent Number

268440

Indian Patent Application Number

737/CHENP/2010

PG Journal Number

36/2015

Publication Date

04-Sep-2015

Grant Date

31-Aug-2015

Date of Filing

08-Feb-2010

Name of Patentee

BOREALIS TECHNOLOGY OY

Applicant Address

PO BOX 330, FIN-06101 PORVOO

Inventors:

#	Inventor's Name	Inventor's Address
1	VAN PARIDON, HENK	TEN BOSCH 15, B-3271 AVERBODE
2	BROEDERS, BERT	SCHOMSTRAAT 24, B-3550 HEUSDEN

PCT International Classification Number

C08L23/08

PCT International Application Number

PCT/EP08/60312

PCT International Filing date

2008-08-06

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	07114113.9	2007-08-09	EUROPEAN UNION