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    • 专利摘要:
    low density polyethylene and use thereof, composition comprising polyethylene and use thereof, process for producing polyethylene, method of polymerizing ethylene, method for an extrusion coating process, article. it is a low density polyethylene that has a molecular weight distribution mw/mn that is 15 or less, a storage modulus g', measured at a loss modulus g of 5 kpa, which is above 3,000 pa , a weight-average molecular weight (mw) that is between 192,000 and 250,000 g/mol and has a melt flow rate (mfr) in accordance with ISO 1133 (190 °C, 2.16 kg) that is greater than 3.0 g/10 min, compositions, a process for producing low-density polyethylene, a low-density polyethylene that is obtainable by the process, a method of continuous ethylene polymerization for introducing vinylidene into a low-density polyethylene, a method for an extrusion coating process or a method for an extrusion lamination process, an article, for example, an extrusion article, an extrusion lamination article, film blown article, film casting article, wire and cable extrusion, injection molding article, p molding article the blow or tube extrusion article and uses of low density polyethylene.
    公开号:BR112014030072B1
    申请号:R112014030072-0
    申请日:2012-12-07
    公开日:2021-08-31
    发明作者:Auli Nummila-Pakarinen；Bernt-Ake Sultan；Björn Voigt；Gabriel Ruess；Martin Anker；Mattias Bergqvist；Thomas Gkourmpis；Thomas Hjertberg
    申请人:Borealis Ag；
    IPC主号:
    专利说明:

    FIELD OF THE INVENTION
    [0001] The present invention relates to a new low density polyethylene, compositions, a process for the production of low density polyethylene, a low density polyethylene that is obtainable by the process, a continuous ethylene polymerization method to introduce vinylidene in a low density polyethylene, a method for an extrusion coating process or an extrusion lamination process, an article, eg, an extrusion article, an extrusion lamination article, film blown article, article of film casting, wire and cable extrusion article, injection molding article, blow molding article or tube extrusion article and use in extrusion coating, extrusion lamination, film blowing, film casting, extrusion wire and cable, injection molding, blow molding or tube extrusion. BACKGROUND OF THE INVENTION
    [0002] Low density polyethylene (LDPE), that is, a polyethylene with a density range from 910 to 940 kg/m3, is an important thermoplastic polymer and has practical use in many industrial applications. Conventional low density polyethylene is produced by a high pressure process at a high temperature through free radical polymerization. Tubular autoclave reactors are the two types of high pressure reactors that are predominantly used to produce low density polyethylene.
    [0003] Furthermore, in extrusion coating, a thin polymer melt film is extruded through a flat die and pressed onto a moving substrate. Extrusion coating is discussed, among others, in Vieweg, Schley and Schwarz: Kunststoff Handbuch, Band IV, Polyolefine, Carl Hanser Verlag (1969), pages 412 to 420. The substrate can be, among others, paper, cardboard, a plastic film or a metal film. The line speed in modern equipment can often be above 300 m/min or above 350 m/min.
    [0004] Higher line speed places heavy demands on the material. Especially, stretch resonance is a problem often encountered with linear polymers such as linear low density polyethylene (LLDPE), high density polyethylene (HDPE) or polypropylene (PP). At the beginning of stretch resonance, large oscillations occur in the flow of polymer melt through the matrix. Consequently, the coating becomes uneven. Stretch resonance is due to the "strain thinning" behavior of linear polymers, where the elongation viscosity decreases with an increasing tensile stress ratio. On the other hand, highly branched polymers such as low density polyethylene exhibit strain hardening, where the elongation viscosity increases with increasing tensile stress ratio.
    [0005] The two most important variables that define the processability of a polymer used for extrusion coating are its stretch (DD) and narrowing (NI). The stretch value should be as high as possible in order to obtain as thin a coating layer as possible and allow a high production speed. At the same time it is desirable to have polymers with a low nip value. This first of all leads to wider substrate coverage, but also less need to trim the outside of the coated substrate. The latter is related to a phenomenon that generates thick edges of the cast film, "edge rib". With increasing narrowing, this thickening will increase and more of the polymer and substrate must be trimmed. Furthermore, mat stability at high line speeds is critical to achieving extrusion coated surfaces with uniform coating weight.
    [0006] Traditionally, autoclave materials, here low density polyethylenes produced in an agitated autoclave reactor, have superior processability for extrusion coating along with satisfactory end product properties. Autoclave materials exhibit a pronounced high molecular weight tail and have a good balance of nip and draw. Tubular materials, here low density polyethylenes produced in a tubular reactor, have so far not shown, due to plug flow in the reactor, such a pronounced high molecular weight tail that is usually found in materials produced in autoclave reactors. Thus, tubular materials have so far not shown a good balance between narrowing and stretching. Especially, the nip will be high with a tubular material and the mat stability will also be lower. In order to have an advantageous balance between narrowing and stretching and web stability at high line speeds, the tubular material must have a high storage modulus G, measured at a loss modulus G" of 5 kPa.
    [0007] Furthermore, since autoclave facilities are aging and there are not many new autoclave reactors being built in the world, there is a need for a technology that generates the same processability. However, as described above, traditionally produced tubular LDPE polymers did not meet the stated requirements for processability. Thus, there is a need for novel tubular reactor polymer structures with advantageous properties to satisfy the requirements of stretch and narrowing and web stability. DESCRIPTION OF THE INVENTION
    [0008] The present invention relates to a low density polyethylene that has a molecular weight distribution Mw/Mn that is 15 or less, a storage modulus G', measured at a loss modulus G" of 5 kPa , which is above 3,000 Pa, a weighted average molecular weight (Mw) that is between 192,000 and 250,000 g/mol and has a melt index (MFR) in accordance with ISO 1133 (190 °C, 2.16 kg) which is greater than 3.0 g/10 min.
    [0009] The low density polyethylene of the present invention is produced in a tubular reactor by radical-initiated polymerization, in which the polymerization is carried out through the reaction of a reaction mixture, comprising ethylene monomers, under the action of one or plus radical initiators such as peroxides, oxygen or combinations thereof and where the inlet temperature of the reaction mixture into the first reaction zone of the reactor is 125 to 132 °C. By selecting the inlet temperature of the reaction mixture in the first reaction zone of the reactor in the polymerization, one can surprisingly produce a low density polyethylene which shows advantageous properties.
    [0010] The reaction mixture, which is compressed, comprises ethylene monomers and optionally chain transfer agents and/or optionally other processing aids.
    [0011] The inlet temperature is the temperature of the reaction mixture at the moment when it enters the first reaction zone of the reactor.
    [0012] The first reaction zone is defined as part of the reactor reaching from the position in the reactor, in which the reaction mixture first contacts the initiator mixture in the first initiator mixture inlet, to the position in the reactor of the second initiator mix input.
    [0013] Methods for determining the temperature of a reaction mixture in a tubular reactor are known in the art. Usually, the temperature of a reaction mixture is measured inside the vessel, which contains the reaction mixture, at a distance from the vessel walls of 2 cm or more. A probe, such as a thermocouple, can be used to measure temperature. In the case where the vessel is a circular object, such as a tube, the temperature is usually measured inside the vessel at a distance from the vessel walls of at least 1/10 of the vessel's internal diameter. As will be readily appreciated, the maximum distance to the walls of a circular vessel is 1/2 the inner diameter of the vessel. Preferably, the maximum distance to the walls of a circular vessel at which the temperature is to be measured; should be 1/3 or less of the inner diameter of the vessel.
    [0014] By selecting the inlet temperature in the first reaction zone of the reactor, one can surprisingly produce a low density polyethylene which shows advantageous properties. For example, the low density polyethylene of the present invention unexpectedly has a very high weighted average molecular weight (Mw) and simultaneously a melt flow rate (MIR). Thus, the weighted average molecular weight (Mw) of the low density polyethylene of the present invention is very high compared to commercially available low density polyethylenes which have a similar melt flow index (MFR) and are produced in tubular reactors, see Table 7 and Figure 4.
    [0015] In addition, the storage modulus G', measured at a loss modulus G" of 5 kPa, has also been shown to be generally higher for the low density polyethylene of the present invention than standard tubular materials (low density polyethylenes). ) produced with conventional techniques. As stated above in the background, a tubular material must have a high storage modulus G", measured at a loss modulus G" of 5 kPa, in order to have a balance between nip and stretch and a stability of blanket at high line speeds.
    [0016] The new low density polyethylene of the present invention exhibits advantageous processability properties, for example, improved extrusion coating properties and/or improved extrusion lamination properties, compared to a regular tubular material. Furthermore, the low density polyethylene of the present invention can be comprised of materials useful as a melt strength modifier. Long chain unbranched linear polyethylenes have for some applications insufficient melt strength, highly branched LDPE are then usually added to increase melt strength. Traditionally, autoclave materials are used, but the new low density polyethylene of the present invention, from a tubular reactor origin, can also surprisingly be used as a melt strength modifier.
    [0017] The low density polyethylene of the present invention is a polyethylene having a density in the range of 910 to 940 kg/m3, for example in the range of 910 to 935 kg/m3.
    [0018] Furthermore, the low density polyethylene of the present invention is also a polyethylene having a density in the range of 900 to 935 kg/m3, for example in the range of 910 to 935 kg/m3.
    [0019] Furthermore, the low density polyethylene of the present invention has a molecular weight distribution Mw/Mn that is 15 or less.
    [0020] Mn is the number average molecular weight and Mw is the weighted average molecular weight. Mw and Mn are determined according to methods known in the art of Gel Permeation Chromatography (GPC). For branched materials, the average molecular weight is determined by the light scattering aid as the branched structure does not elute according to molecular weight as for linear materials.
    [0021] The molecular weight distribution (Mw/Mn), which is also called MWD or PDI (polydiversity index), is a key parameter for extrusion coating properties and extrusion lamination properties. For the nip, a high molecular weight material with slow relaxation in the gap of the extrusion coating equipment is required, but for high yield in the extruder and for high draw speed a low molecular weight part must be presented.
    [0022] The low density polyethylene of the present invention, which is produced at a low inlet temperature, has a very high molecular weight (Mw). The Mn should not be too low (ie not below 10,000 for a material with 150,000 to 250,000 Mw) as it will then contain a very large amount of low molecular weight material. This low molecular weight material will cause increased levels of smoke during extrusion and also increased levels of hexane extractables in the finished article. This is shown by the higher weighted average molecular weight compared to materials produced with a higher inlet temperature (see Table 7). The increase in Mw appears to be much more dependent on inlet temperature rather than, for example, high peak temperatures (see Tables 2 to 6). The high molecular weight portion of the low density polyethylene matrix has a significant amount of branches of significant length, thus allowing the entire system to sustain superior mechanical strain. The level of long and short chain branching can be directly correlated to the density of low density polyethylene, so for systems to decrease the overall density, the branching level is increasing. The reasoning behind the mechanical deformation capabilities of such a system is due to the extensive level of entanglements present. Since the high molecular weight polymer chains are expected to be relatively long whereas the level of long chain branching is expected to be significant, it can be assumed that the high molecular weight chains will host the largest branches. Since these branches are also quite long, a significant level of entanglement between fragments (segments) of the same or different strands will be present. These tangles are known to induce increased mechanical deformation resistance in a polymer and the longer and denser they are, the more they increase the overall effect. The rationale for such resistance has to do with the mobility of polymer fragments located on either side of the entanglement point. As the deformation force is increased, the system will undergo chain slip through entanglement point, chain disentanglement, chain reentanglement and finally chain breakage. Obviously, since the entanglement points are increased and the polymer fragment between the two consecutive entanglement points is expected to be substantial (after all the branches are long and the molecular weight is large), the eventual chain breakage will be delayed due to to constant slips, disentanglement and reentanglement thus leading to increased resistance to mechanical deformation. This effect is seen as an increased elasticity index G’ (5 kPa). An increase in the value of this parameter correlates very well with improved narrowing properties (see Figure 1).
    [0023] Autoclave materials, here low density polyethylenes produced in an agitated autoclave reactor, which generate a pronounced high molecular weight tail (and very high Mw/Mn) have a good balance between nip and stretch. Tubular materials, here low density polyethylenes produced in a tubular reactor, will not, due to plug flow in the reactor, have the pronounced high molecular weight tail usually found in materials produced in autoclave reactors and will not have a good balance between narrowing and stretching. Especially, the nip will be high with a tubular material and the mat stability is also lower. In order to have a balance between narrowing and stretching and web stability at high line speeds, the tubular material must have a higher molecular weight in conjunction with a high MFR. Also, the Mw/Mn should not be too high when having a high Mw, this means that the Mn should be increased by increasing Mw. If the Mn is too low, the material will contain too much low molecular weight material which can cause increased levels of extrusion smoke and increased levels of hexane extractables in the finished article. This was, according to the invention, surprisingly achieved in polymerization in a tubular reactor having a lower inlet temperature in the first reaction zone.
    [0024] In a further embodiment, the low density polyethylene of the present invention has a molecular weight distribution Mw/Mn that is 14.9 or less.
    [0025] In yet a further embodiment, the molecular weight distribution Mw/Mn is 14.8 or less.
    [0026] Still, a further embodiment of the present invention provides a low density polyethylene in which the molecular weight distribution Mw/Mn is 14.7 or less.
    [0027] Yet another embodiment of the present invention provides a low density polyethylene of the present invention wherein the molecular weight distribution Mw/Mn is 14.6 or less.
    [0028] In yet a further embodiment, the molecular weight distribution Mw/Mn is 14.5 or less.
    [0029] In addition, the suitable minimum molecular weight distribution limits of the molecular weight distribution ranges may be 8, 9, 10, 11, 12, 13, 14 or, alternatively, 14.2 and these weight distribution limits Lower molecular weight distributions may each be used in any molecular weight distribution range, open or closed, as described herein, i.e., used in combination with the given upper molecular weight distribution range of any given range of molecular weight distributions. molecular weight as described herein.
    [0030] Furthermore, the low density polyethylene of the present invention has a storage modulus G', measured at a loss modulus G" of 5 kPa, which is above 3,000 Pa.
    [0031] In a further embodiment, the low density polyethylene of the present invention has a storage modulus G', measured at a loss modulus G" of 5 kPa, which is above 3,100 Pa.
    [0032] Still in a further modality, the low density polyethylene of the present invention has a storage modulus G', measured at a loss modulus G" of 5 kPa, which is above 3,200 Pa.
    [0033] Still, a further embodiment of the present invention provides a low density polyethylene having a storage modulus G', measured at a loss modulus G" of 5 kPa, which is above 3300 Pa.
    [0034] In a further embodiment, the low density polyethylene of the present invention has a storage modulus G', measured at a loss modulus G" of 5 kPa, which is above 3400 Pa.
    [0035] In yet another embodiment, the low density polyethylene of the present invention has a storage modulus G', measured at a loss modulus G" of 5 kPa, which is above 3,450 Pa.
    [0036] Still in a further modality, the low density polyethylene of the present invention has a storage modulus G', measured at a loss modulus G" of 5 kPa, which is above 3,500 Pa.
    [0037] Furthermore, the appropriate upper limits of storage module G', measured at a 5 kPa loss G" modulus, of the storage module G' ranges, measured at a 5 kPa G" loss modulus, can be 3800, 3750, 3700, 3650, 3600 or alternatively 3,550 Pa and these storage modulus G' upper limits, measured on a 5 kPa G" loss modulus, can each be used in any range of storage module G', measured in a loss module G" of 5 kPa, open or closed, as described in this document, ie used in combination with the lower limit of storage module G', measured in a module of 5 kPa G" loss of any storage module range G' measured on a 5 kPa G" loss module as described herein.
    [0038] Furthermore, the low density polyethylene of the present invention has a weighted average molecular weight (Mw) that is between 192,000 and 250,000 g/mol.
    [0039] In a further embodiment, the low density polyethylene of the present invention has a weighted average molecular weight (Mw) that is between 195,000 and 250,000 g/mol.
    [0040] Still in a further embodiment, the low density polyethylene of the present invention has a weighted average molecular weight (Mw) that is between 198,000 and 250,000 g/mol.
    [0041] In a further embodiment, the low density polyethylene of the present invention has a weighted average molecular weight (Mw) that is between 192,000 and 245,000 g/mol.
    [0042] Still in a further embodiment, the low density polyethylene of the present invention has a weighted average molecular weight (Mw) that is between 192,000 and 240,000 g/mol.
    [0043] In a further embodiment, the low density polyethylene of the present invention has a weighted average molecular weight (Mw) that is between 200,000 and 250,000 g/mol.
    [0044] Still in a further embodiment, the low density polyethylene of the present invention has a weighted average molecular weight (Mw) that is between 200,000 and 240,000 g/mol.
    [0045] Furthermore, the low density polyethylene of the present invention has a melt flow index (MFR) in accordance with ISO 1133 (190°C, 2.16 kg) which is greater than 3.0 g/10 min.
    [0046] In a further embodiment, the low density polyethylene of the present invention has a melt flow index (MFR) in accordance with ISO 1133 (190 °C, 2.16 kg) which is at least 3.5 g/10 min .
    [0047] In yet a further embodiment, the low density polyethylene of the present invention has a melt flow index (MFR) in accordance with ISO 1133 (190 °C, 2.16 kg) which is at least 4.0 g/10 min.
    [0048] In yet another embodiment, the low density polyethylene of the present invention has a melt flow index (MFR) in accordance with ISO 1133 (190 °C, 2.16 kg) which is at least 4.2 g/10 min .
    [0049] Yet a further embodiment of the present invention provides a low density polyethylene having a melt flow index (MFR) in accordance with ISO 1133 (190°C, 2.16 kg) that is at least 4.5 g/ 10 min.
    [0050] In a further embodiment, the low density polyethylene of the present invention has a melt flow index (MFR) in accordance with ISO 1133 (190 °C, 2.16 kg) which is at least 5.0 g/10 min .
    [0051] In yet another embodiment, the low density polyethylene of the present invention has a melt flow index (MFR) in accordance with ISO 1133 (190°C, 2.16 kg) which is at least 5.2 g/10 min .
    [0052] In yet a further embodiment, the low density polyethylene of the present invention has a melt flow index (MFR) in accordance with ISO 1133 (190 °C, 2.16 kg) which is at least 5.4 g/10 min.
    [0053] In yet another embodiment, the low density polyethylene of the present invention has a melt flow index (MFR) in accordance with ISO 1133 (190 °C, 2.16 kg) that is at least 5.5 g/10 min .
    [0054] In yet a further embodiment, the low density polyethylene of the present invention has a melt flow index (MFR) in accordance with ISO 1133 (190°C, 2.16 kg) which is at least 5.6 g/10 min.
    [0055] In yet another embodiment, the low density polyethylene of the present invention has a melt flow index (MFR) in accordance with ISO 1133 (190°C, 2.16 kg) which is at least 5.7 g/10 min .
    [0056] A further embodiment of the present invention provides a low density polyethylene as described herein, wherein the low density polyethylene is a homopolymer of ethylene.
    [0057] Still, a further embodiment of the present invention provides a low density polyethylene as described herein, wherein the low density polyethylene has a density in the range of 900 to 935 kg/m3, for example, in the range of 910 to 935 kg/m3.
    [0058] A further embodiment of the present invention provides a low density polyethylene as described herein, wherein the low density polyethylene is produced in a tubular reactor.
    [0059] A low density polyethylene that is produced in a tubular reactor traditionally has a molecular weight distribution without the pronounced high molecular weight tail in autoclave materials. This difference in the appearance of the molecular weight distribution is expected and detectable by one skilled in the art.
    [0060] Furthermore, the low density polyethylene of the present invention has a vinylidene content that is at least 15/100 kC, where 15/100 kC means 15 vinylidene groups per 100,000 carbons.
    [0061] Vinylidene is formed by the beta splitting of tertiary carbon radicals. With branching increased by the amount of larger radical initiator, the number of tertiary carbon radicals will increase and so will the likelihood of beta splitting and creation of a vinylidene. The vinylidene content will then be an indirect measure of the amount of branching introduced into the low density polyethylene of the present invention.
    [0062] The branching originates from the radical transfer to the polymer backbone. These transfer reactions are necessary for the differentiation of molecular weights between the chains, propagation leading to long chain branching or termination through combination leading to two chains being fused into one. The introduction of the high molecular weight material and long chain branching causes the material, here the low density polyethylene of the present invention, to exhibit melt tangles which lead to greater melt elasticity (reduced nip).
    [0063] In a further embodiment, the low density polyethylene of the present invention has a vinylidene content that is at least 17/100 kC.
    [0064] Still in a further modality, the vinylidene content is at least 19/100 kC.
    [0065] Still, a further embodiment of the present invention provides a low density polyethylene wherein the vinylidene content is at least 20/100 kC.
    [0066] In a further embodiment of the present invention, a low density polyethylene is provided wherein the vinylidene content is at least 22/100 kC.
    [0067] Yet another embodiment of the present invention provides a low density polyethylene wherein the vinylidene content is at least 24/100 kC.
    [0068] In a further embodiment, the low density polyethylene of the present invention has a vinylidene content that is at least 25/100 kC.
    [0069] In addition, suitable upper vinylidene content limits of vinylidene content ranges may be 38, 36, 34, 32, 30, 28, or alternatively 26 and these upper vinylidene content limits may each be , used in any vinylidene content range, open or closed, as described herein, that is, used in combination with the given lower vinylidene content range of any vinylidene content range, as described herein.
    [0070] The present invention also relates to compositions comprising low density polyethylene, such compositions may be useful in extrusion coating and/or extrusion lamination. There are commercially available grades of high density and linear low density polyethylene and polypropylene for extrusion coating where improved processability is achieved by modifying them with autoclave LDPE. A tubular LDPE with adequate melt elasticity can be used for the same purpose.
    [0071] In a further aspect, the present invention relates to a composition comprising the new low density polyethylene, such composition may be useful in extrusion coating and/or extrusion lamination processes.
    Accordingly, the present invention provides a composition, useful in extrusion coating and/or extrusion lamination processes, such composition comprises the low density polyethylene of the present invention and optionally additional additional components, e.g. olefin such as polyethylene or polypropylene, for example linear homopolymers of ethylene and/or copolymers of ethylene and one or more alpha-olefin comonomers having from 3 to 20 carbon atoms. Ethylene homo and copolymers, propylene homo and copolymers and 1-butene homo and copolymers are also examples of additional components. Said olefin polymers can be produced by polymerizing olefins in the presence of transition metal polymerization catalysts. Additional components include, for example, bimodal ethylene copolymers and at least two alpha-olefin comonomers, such as those described in WO 2005/002744 and WO 03/66698.
    [0073] Furthermore, examples of such additional components can be, for example, olefin polymers such as ethylene homo and copolymers, propylene homo and copolymers and 1-butene homo and copolymers.
    [0074] Furthermore, the composition of the present invention may additionally comprise antioxidants, stabilizers, other additives and fillers, which are all known in the art.
    [0075] The composition of the present invention, useful in extrusion coating processes and/or extrusion lamination processes, may include the new low density polyethylene in an amount of 5 to 40% by weight, based on the total weight of the composition. In a further embodiment, the composition may comprise from 10 to 35% by weight or alternatively from 20 to 35% by weight of the new low density polyethylene. Furthermore, in addition to the new low density polyethylene, the composition may additionally comprise from 60 to 95% by weight, for example from 65 to 90% and for example from 65 to 80% of at least one additional component selected from a linear ethylene homopolymer and an ethylene copolymer with one or more alpha-olefin comonomers having from 3 to 20 carbon atoms.
    [0076] Still, a further embodiment of the invention provides a composition as described herein which may comprise the low density polyethylene in an amount of 5 to 40% by weight based on the total weight of the composition and such composition may further comprise at least one olefin polymer prepared in the presence of a transition metal catalyst, such at least one olefin polymer can be selected from polyethylene, polypropylene or poly-1-butene homo or copolymers.
    [0077] A further embodiment of the invention provides a composition comprising - the low density polyethylene of the present invention, and - at least one olefin polymer prepared in the presence of a transition metal catalyst, wherein the olefin polymer can be selected from homo or copolymers of polyethylene, polypropylene or poly-1-butene and the low density polyethylene may be present in an amount of 5 to 40% by weight, based on the total weight of the composition.
    [0078] According to the present invention, the composition can be processed on an extrusion coating line with a high line speed and minimal risk of stretch resonance.
    [0079] The compositions of the present invention can be extrusion coated onto different substrates at high line speeds and the compositions can have a reduced tendency to undergo stretch resonance and a uniform coating distribution can be obtained. This would allow for a high throughput on the coating line with a good amount of product maintained. Thus, the low density polyethylene according to the present invention can be used to make compositions which can exhibit excellent processability. On the other hand, any advantageous properties of any composition components present in the composition can be maintained. Therefore, the low density polyethylene according to the present invention can be used to improve processability and lower smoke levels during processing and extractables from hexane, of different compositions that have various advantageous properties, such as good optical properties, good properties sealing and good abrasion resistance. Furthermore, the compositions of the present invention can have low shrinkage and excellent processability at high line speeds (meaning high draw and run stability) when used in extrusion coating. In particular, the nip decreases as the line speed increases, which results in better coating performance at higher throughput. A low nip leads to a low amount of wasted substrate material as the uncoated portion of the substrate needs to be cut and discarded. The substrate to be coated can be any substrate known in the art, such as paper, cardboard, metal sheet paper, plastic sheet and cellophane sheet. To improve adhesion between the substrate and a polymer coating layer, methods commonly known in the art can be used, such as ozone treatment of the molten polymer film, flame treatment and corona treatment of the substrate, an adhesive layer can be used. used and an adhesion promoter can be used.
    [0080] A further object of the invention is a process for the production of a low density polyethylene of the present invention in a tubular reactor by radical initiated polymerization under high pressure, in which the polymerization is carried out through the reaction of a reaction mixture , which comprises ethylene monomers, under the action of one or more radical initiators, such as peroxides, oxygen or combinations thereof and in which the inlet temperature of the reaction mixture in the first reaction zone of the reactor is from 125 to 132 ° Ç.
    [0081] Still, a further object of the invention is a process for the production of a low density polyethylene of the present invention in a tubular reactor by radical initiated polymerization under high pressure, such pressure is from 100 to 300 MPa (1,000 to 3,000 bar), for example, from 150 to 250 MPa (1,500 to 2,500 bar), in which the polymerization is carried out through the reaction of a reaction mixture, comprising ethylene monomers, under the action of one or more radical initiators, such as as peroxides, oxygen or combinations thereof and where the inlet temperature of the reaction mixture into the first reaction zone of the reactor is 125 to 132 °C.
    [0082] The reaction mixture and the inlet temperature are both as defined in this document.
    [0083] By selecting the inlet temperature in the first reaction zone of the reactor to be 125 to 132 °C, one can surprisingly produce a low density polyethylene which exhibits advantageous properties.
    [0084] According to the embodiments of the present invention "the reactor inlet temperature" means the inlet temperature in the first reaction zone of the reactor.
    [0085] Still, a further object of the invention includes a process for the production of low density polyethylene, as described herein, in which the inlet temperature in the first reaction zone of the reactor is from 125 to 131 °C.
    [0086] Yet another object of the invention includes a process for the production of low density polyethylene, as described herein, in which the inlet temperature in the first reaction zone of the reactor is from 125 to 130 °C.
    [0087] In a further embodiment of the present invention, the invention includes a process for the production of low density polyethylene, as described herein, in which the inlet temperature in the first reaction zone of the reactor is from 126 to 132 ° C or alternatively 126 to 131 °C.
    [0088] An embodiment of the present invention provides a process for the production of low density polyethylene, as described herein, in which the inlet temperature in the first reaction zone of the reactor is from 127 to 132 °C or, alternatively, from 127 to 131°C.
    [0089] A further object of the invention is a process for the production of a low-density polyethylene of the present invention in a tubular reactor by radical-initiated polymerization under high pressure, in which the polymerization is carried out through the reaction of the reaction mixture, comprising ethylene monomers, under the action of one or more radical initiators, such as peroxides, oxygen or combinations thereof, in which the inlet temperature in the first reaction zone of the reactor is selected, as described in any of the described modalities in this document. By selecting the inlet temperature in the first reaction zone of the reactor, one can surprisingly produce a low density polyethylene which exhibits advantageous properties.
    [0090] Still a further object of the invention is a process for the production of a low density polyethylene of the present invention in a tubular reactor by radical initiated polymerization under high pressure, such pressure is from 100 to 300 Mpa (1,000 to 3,000 bar ), for example, from 150 to 250 Mpa (1,500 to 2,500 bar), in which the polymerization is carried out through the reaction of the reaction mixture, which comprises ethylene monomers, under the action of one or more radical initiators, such as peroxides , oxygen, or combinations thereof, wherein the inlet temperature to the first reaction zone of the reactor is selected, as described in any of the embodiments described herein. By selecting the inlet temperature in the first reaction zone of the reactor, one can surprisingly produce a low density polyethylene which exhibits advantageous properties.
    [0091] Still, a further object of the invention includes a process for the production of the low density polyethylene of the present invention in a tubular reactor under high pressure by radical-initiated polymerization in which the polymerization is carried out through the reaction of the reaction mixture, comprising ethylene monomers, under the action of one or more radical initiators, such as peroxides, oxygen or combinations thereof, preferably under the action of one or more peroxides, which comprise low temperature decomposition peroxides, for example, peroxides which have a half-life temperature of 0.1 hour which is below 100°C, wherein the inlet temperature into the first reaction zone of the reactor is selected as described in any of the embodiments described herein.
    [0092] Yet another object of the invention includes a process for the production of the low density polyethylene of the present invention in a tubular reactor under high pressure, such pressure is from 100 to 300 MPa (1,000 to 3,000 bar), for example from 150 to 250 MPa (1,500 to 2,500 bar), by radical-initiated polymerization in which the polymerization is carried out through the reaction of the reaction mixture, which comprises ethylene monomers, under the action of one or more radical initiators, such as peroxides, oxygen or combinations thereof, preferably under the action of one or more peroxides, which comprise low-temperature decomposition peroxides, for example, peroxides having a half-life temperature of 0.1 hour which is below 100°C, wherein the inlet temperature in the first reaction zone of the reactor is selected, as described in any of the modalities described in this document.
    [0093] Another object of the invention includes a process for the production of the low density polyethylene of the present invention in a tubular reactor under high pressure by radical initiated polymerization in which the polymerization is carried out through the reaction of the reaction mixture, which comprises monomers of ethylene, under the action of one or more radical initiators, which are peroxides, which comprise low-temperature decomposition peroxides, for example, peroxides which have a half-life temperature of 0.1 hour which is below 100 °C, wherein the inlet temperature to the first reaction zone of the reactor is selected, as described in any of the embodiments described herein.
    [0094] Yet another object of the invention includes a process for the production of the low density polyethylene of the present invention in a tubular reactor under high pressure, such pressure is from 100 to 300 MPa (1,000 to 3,000 bar), for example from 150 to 250 MPa (1,500 to 2,500 bar), by radical initiated polymerization in which the polymerization is carried out through the reaction of the reaction mixture, which comprises ethylene monomers, under the action of one or more radical initiators, which are peroxides, which comprise low-temperature decomposition peroxides, for example, peroxides that have a half-life temperature of 0.1 hour that is below 100 °C, where the inlet temperature in the first reaction zone of the reactor is selected, as described in any of the modalities described in this document.
    [0095] The present invention also relates to a continuous ethylene polymerization method to introduce a high content of vinylidene into a low-density polyethylene, wherein the vinylidene is introduced through the reaction of a reaction mixture, which comprises monomers of ethylene, under the action of one or more radical initiators, such as peroxides, oxygen or combinations thereof, and by selecting the inlet temperature of the reaction mixture in the first reaction zone of the reactor to be from 125 to 132 °C.
    [0096] Furthermore, a continuous ethylene polymerization method to introduce a vinylidene into a low density polyethylene is disclosed, in which the vinylidene is introduced by selecting a reaction mixture inlet temperature in the first reaction zone of the reactor which is 125 to 132 °C.
    [0097] Furthermore, the present invention also relates to a continuous ethylene polymerization method to introduce a high content of vinylidene into a low density polyethylene, wherein the vinylidene is introduced by selecting the inlet temperature of the reaction mixture in the first reaction zone of the reactor to be 125 to 132 °C. Furthermore, the continuous polymerization of ethylene to introduce a high content of vinylidene into a low-density polyethylene is a radical-initiated polymerization in which the polymerization is carried out by reacting the reaction mixture, which comprises ethylene monomers, under the action of one or more radical initiators, such as peroxides, oxygen or combinations thereof, preferably under the action of one or more peroxides, which comprise low-temperature decomposition peroxides, for example, peroxides having a half-life temperature of 0. 1 hour which is below 100 °C.
    [0098] Still, a further object of the invention includes a continuous ethylene polymerization method to introduce a high content of vinylidene into a low density polyethylene, as described herein, wherein the inlet temperature of the reaction mixture in the first Reaction zone of the reactor is 125 to 131 °C.
    [0099] Another object of the invention includes a continuous ethylene polymerization method to introduce a high content of vinylidene into a low density polyethylene, as described herein, wherein the inlet temperature of the reaction mixture in the first reaction zone of the reactor is from 125 to 130 °C.
    [00100] In a further embodiment of the present invention, the invention includes a continuous ethylene polymerization method to introduce a high content of vinylidene into a low density polyethylene, as described herein, wherein the inlet temperature of the mixture of reaction in the first reaction zone of the reactor is from 126 to 132 °C or, alternatively, from 126 to 131 °C.
    [00101] An embodiment of the present invention provides a continuous ethylene polymerization method to introduce a high content of vinylidene into a low density polyethylene, as described herein, wherein the inlet temperature of the reaction mixture in the first zone of reactor reaction is 127 to 132 °C or alternatively 127 to 131 °C.
    [00102] An additional embodiment discloses the continuous ethylene polymerization method to introduce a high content of vinylidene into a low density polyethylene, where the ethylene polymerization is a radical-initiated polymerization and the polymerization is carried out through the reaction of the mixture of reaction, which comprises ethylene monomers, under the action of one or more radical initiators, such as peroxides, oxygen or combinations thereof, preferably under the action of one or more peroxides, which comprise low temperature decomposition peroxides, by example, peroxides that have a half-life temperature of 0.1 hour that is below 100 °C, wherein the inlet temperature in the first reaction zone of the reactor is selected, as described in any of the modalities described in this document .
    [00103] Additional embodiments disclose a process for the production of low density polyethylene, as described herein, or a continuous ethylene polymerization method, as described herein, in which the inlet temperature in the first reaction zone of the reactor is selected, as described in any of the embodiments described herein, and a free radical initiator cocktail is used which is composed of the following free radical initiators, wherein the half-life temperature is 0.1 hour (T^) is given for each radical initiator: Initiator A (0.1 hour T^ at 75 to 90°C in chlorobenzene), Initiator B (0.1 hour T^ at 80 to 95°C in chlorobenzene), Initiator C ( 0.1 hour T4 at 105 to 125 °C in chlorobenzene), Initiator D (0.1 hour T4 at 125 to 140 °C in chlorobenzene) Initiator E (0.1 hour T4 at 130 to 145 °C °C in chlorobenzene) and Initiator F (T4 0.1 hour at 155 to 175 °C in chlorobenzene).
    [00104] A further embodiment discloses a low density polyethylene which is obtainable by the process of the present invention as described herein.
    [00105] Another object of the invention relates to a method for an extrusion coating process, such method comprises extrusion coating a flat substrate by extruding the low density polyethylene of the invention or composition of the invention in a molten state through of a flat matrix on said substrate or a method for an extrusion lamination process using the low density polyethylene of the invention or the composition of the invention.
    [00106] In an extrusion coating process, a substrate is coated with polymer. For the sake of completeness, it is stated herein that extrusion lamination processes are also included in accordance with the invention and any modification to such a process will be clear to one skilled in the art. The substrate is typically a fibrous substrate, such as paper, cardboard or Kraft paper or woven or non-woven cloths; a sheet of metal, such as aluminum foil; or a plastic film such as axially oriented polypropylene film, PET film, PA film or cellophane film. Additional substrates may also include less flexible substrates, such as substrates comprising wood or thick metal. The polymer is extruded onto the moving substrate through a flat die. Polymer melt exits the matrix typically at a high temperature, typically between 275 to 330°C. After leaving the matrix, the polymer melt is oxidized when it comes into contact with air. Oxidation improves adhesion between the coating and the substrate.
    [00107] When the fusion leaves the die, the fusion film is pulled down in a tangent line between two rollers, the pressure roller and the cooling roller, situated below the die. The substrate, which moves at a speed that is greater than that of the fusing film, stretches the film to the required thickness. The pressure between the two rollers forces the film onto the substrate. Furthermore, the film is cooled and solidified by the low temperature of the cooling roll. The draw ratio, which is one of the characteristic parameters of the extrusion coating process, is the ratio between the matrix gap and the thickness of the polymer film on the substrate.
    [00108] The description of the extrusion coating process is given, for example, in Crystalline Olefin Polymers, Part II, by R.A.V. Raff and K.W. Doak (Interscience Publishers, 1964), pages 478 to 484 or Plastics Processing Data Handbook, by Dominick V. Rosato (Chapman & Hall, 1997), pages 273 to 277.
    [00109] An embodiment of the present invention discloses an article, e.g., an extrusion article, e.g., an extrusion coating article or an extrusion laminating article, film blown article, film casting article, article wire and cable extrusion, injection molding article, blow molding article or tube extrusion article comprising the low density polyethylene of the present invention or the composition of the present invention.
    [00110] According to the invention, there is disclosed an extrusion coating article or an extrusion laminating article comprising the low density polyethylene of the invention or the composition of the invention.
    [00111] A further embodiment discloses an article, for example an extrusion article, comprising at least one layer of the low density polyethylene of the invention or at least one layer of the composition of the invention.
    [00112] Furthermore, also according to the invention, the article may comprise a substrate and at least one layer coated by extrusion based on the low density polyethylene of the invention or the composition of the invention.
    [00113] As mentioned above, the substrate is coated by extrusion and thus at least one surface of the substrate is coated. It is, however, within the scope of the invention that both sides of the substrate, i.e. the outer and inner surface (side) of the substrate are coated by extrusion. It is also within the scope of the invention that the layer based on the low density polyethylene of the invention or based on the composition of the invention is in direct contact with the substrate or that between the substrate and the layer based on the low density polyethylene of the invention or based on the composition of the invention, at least one additional layer is inserted, such as an adhesive layer. Also included are modalities in which the layer based on the low density polyethylene of the invention or based on the composition of the invention has been subjected to ozone treatment or flame treatment and/or the substrate has been subjected to corona treatment, respectively, to improve the adhesion between the layer based on the low density polyethylene of the invention or based on the composition of the invention and the substrate.
    [00114] The layer based on the low density polyethylene of the invention or based on the composition of the invention comprised in the substrate coated by extrusion preferably has a thickness in the range of 5 to 1000 µm, preferably in the range of 10 at 100 µm. The specific thickness will be selected according to the nature of the substrate, its expected subsequent handling conditions and, most importantly, the subsequent use of the final product. Substrate thickness can generally be freely chosen and has no effect on coating processing. It may typically be 11,000 µm, for example 5 to 300 µm.
    [00115] The extrusion coating process is preferably carried out using conventional extrusion coating techniques. Therefore, the low density polyethylene of the invention or the composition of the invention is fed to an extrusion device. From the extruder, the melt of the low density polyethylene of the invention or the composition of the invention is passed through a flat die to the substrate to be coated. Due to the distance between the matrix flap and the tangency line, the molten plastic is oxidized in air for a short period, usually leading to improved adhesion between the coating and the substrate. The coated substrate is cooled on a cooling roller. The coating layer can be treated with corona post-treatment to make it suitable for, for example, printing or gluing. Then, the edges of the blanket can be trimmed and the blanket can be rolled up. The die width typically depends on the size of the extruder used. Thus, with 90 mm extruders the width can suitably be within the range of 600 to 1,200 mm, with 115 mm extruders from 900 to 2,500 mm, 150 mm extruders from 1,000 to 4,000 mm and 200 mm extruders from 3,000 to 5,000 mm. It is also possible to employ a coating line with at least two extruders to make it possible to produce multilayer coatings with different polymers. It is also possible to have arrangements for treating melting of the low density polyethylene of the invention or the composition of the invention, which leaves the matrix to improve adhesion, for example, by treatment with ozone and the substrate with corona treatment or flame treatment. For the corona treatment, for example, the substrate is passed between the conductive elements that serve as electrodes, with such a high voltage, usually an alternating voltage (about 10,000 V and 10,000 Hz), being applied between the electrodes that sprinkle or discharge corona may occur.
    [00116] A further embodiment of the invention discloses a method for an extrusion coating process, such method comprises extrusion coating a flat substrate by extrusion of the low density polyethylene of the invention or the composition of the invention in a molten state through a flat matrix on said substrate.
    [00117] With the method for the extrusion coating process, such method comprises extruding the low density polyethylene of the invention, it has surprisingly been shown to be possible to use a low density polyethylene from a tubular reactor source in an extrusion coating process and to achieve good necking properties which are usually poor for a traditionally produced tubular LDPE. In addition to a good nip, also a good mat stability where no edge weave is noticed at a line speed of 300 m/min and where a uniform coating weight is obtained.
    [00118] Edge interlacing is defined as having started at the line speed where the mat edges move 2mm or more.
    [00119] An object of the invention is the use of a low density polyethylene of the present invention or the use of a composition comprising the low density polyethylene of the present invention, for example, in extrusion coating, extrusion lamination, air blowing. film, film casting, wire and cable extrusion, injection molding, blow molding or tube extrusion.
    [00120] The low density polyethylene of the invention or the composition of the invention can be used in many applications such as, for example, in extrusion coating and/or extrusion lamination. BRIEF DESCRIPTION OF THE FIGURES
    [00121] Figure 1 describes the narrowing of Materials A, B, D and E at 400 m/min as a function of the storage modulus G', measured in a loss modulus G" of 5 kPa.
    [00122] Figure 2 describes the relationship between the first reaction zone inlet temperature and the molecular weight Mw.
    [00123] Figure 3 describes the narrowing of Material A to D at 400 m/min as a function of vinylidene content.
    [00124] Figure 4 describes the relationship between MFR and Mw for commercially available tubular LDPE and innovative examples. Description of Analytical Methods Molecular weights, molecular weight distribution (Mn, Mw, MWD) — GPC
    [00125] A GPC PL 220 (Agilent) equipped with a refractive index (RI), an in-line 4 capillary bridge viscometer (PL-BV 400-HT) and double light scattering detector (PL-light scattering detector). LS 15/90) with an angle of 15° and 90° was used. 3x Olexis and 1x Olexis pre-columns with Agilent as stationary phase and 1,2,4-trichlorobenzene (TCB, stabilized with 250 mg/l 2,6-Di tert-butyl-4-methyl-phenol) as mobile phase at 160°C °C and a constant flow rate of 1 ml/min were applied. 200 µl of the sample solution was injected per analysis. All samples were prepared by dissolving 8.0 to 12.0 mg of polymer in 10 ml (at 160 °C) of stabilized TCB (same as mobile phase) for 2.5 hours for PP or 3 hours for PE at 160 °C under continuous gentle agitation. The injected concentration of the polymer solution at 160°C (c160°C) was determined as follows.

    [00126] With: w25 (polymer weight) and V25 (TCB volume at 25 °C).
    [00127] The corresponding detector constants as well as the internal detector delay volumes were determined with a narrow PS standard (MWD = 1.01) with a molar mass of 132,900 g/mol and a viscosity of 0.4789 dl/g . The corresponding dn/dc for the PS standard used in TCB is 0.053 cm3/g. The calculation was performed using Cirrus Multi-Offline SEC-Software Version 3.2 (Agilent).
    [00128] The molar mass in each elution slice was calculated using the 15° light scattering angle. Data collection, data processing and calculation were performed using Cirrus Multi SEC-Software Version 3.2. The molecular weight was calculated using the option in the Cirrus software "use angle LS 15" in the field "Sample calculation options" subfield "MW data from slice from". The dn/dc used for the determination of molecular weight was calculated from the RI detector constant, the concentration c of the sample and the area of the detector response of the analyzed sample.
    [00129] This molecular weight in each slice is calculated as described by C. Jackson and HG Barth (C. Jackson and HG Barth, "Molecular Weight Sensitive Detectors" in: Handbook of Size Exclusion Chromatography and related techniques, C. -S. Wu, 2nd edition, Marcel Dekker, New York, 2004, page 103) in low angle. For the low and high molecular region in which less signal from the LS detector or RI detector respectively was achieved, a linear fit was used to correlate the elution volume to the corresponding molecular weight. Depending on the sample, the region of the linear fit was adjusted.
    [00130] The molecular weight averages (Mz, Mw and Mn), the molecular weight distribution (MWD) and its amplitude, described by the polydispersity index, PDI = Mw/Mn (where Mn is the molecular weight by number average and Mw is the weighted average molecular weight) are determined by Gel Permeation Chromatography (GPC) in accordance with ISO 16014-4:2003 and ASTM D 6474-99 using the following formulas:

    [00131] For a constant elution volume range ΔVi, where Ai and Mi are the chromatographic peak slice area and the polyolefin molecular weight (MW) determined by GPC-LS. melt flow rate
    [00132] The melt flow rate of low density polyethylene was determined according to ISO 1133 at 190 °C under a load of 2.16 kg (MFR). The melt flow rate is that amount of polymer in grams that the tester has standardized to ISO 1133 extrusions within 10 minutes at a temperature of 190°C under a load of 2.16 kg. Storage module (G') Dynamic Shear Measurements (frequency sweep measurements)
    [00133] The characterization of polymer melts by dynamic shear measurements complies with ISO 6721-1 and 6721-10 standards. Measurements were performed on an Anton Paar MCR501 stress-controlled rotational rheometer, equipped with a 25 mm parallel plate geometry. Measurements were performed on compression molded plates, using a nitrogen atmosphere and establishing a strain within the linear viscoelastic regime. Oscillatory shear tests were performed at 190 °C applying a frequency range between 0.01 and 600 rad/s and establishing a gap of 1.3 mm.
    [00134] In a dynamic shear experiment, the probe is subjected to a homogeneous deformation to a shear stress or sinusoidal variable shear stress (mode controlled by stress and stress, respectively). In a voltage-controlled experiment, the probe is subjected to a sinusoidal voltage that can be expressed by

    [00135] If the applied voltage is within the linear viscoelastic regime, the resulting sinusoidal stress response can be triggered by
    where °o and K0 are the stress and voltage amplitudes, respectively t is the angular frequency 5 is the phase shift (loss angle between the applied voltage and stress response) t is the time
    [00136] Dynamic test results are typically expressed through several different rheological functions, that is, the shear storage module G', the shear loss module, G", the complex shear module, G*, the complex shear viscosity, q*, the dynamic shear viscosity, n', the out-of-phase component of the complex shear viscosity n'', and the loss tangent, tan δ which can be expressed as follows:

    [00137] In addition to the rheological functions mentioned above, one can also determine other rheological parameters such as the so-called elastic index El(x). The elasticity index EI(x) is the storage modulus value G' determined for a loss modulus value, G" of x kPa and can be described by equation (9).

    [00138] For example, the EI(5 kPa) is defined by the value of the storage modulus G', determined for a value of G" equal to 5 kPa. References: [1] “Rheological characterization of polyethylene fractions” Heino, EL , Lehtinen, A., Tanner J., Seppald, J., Neste Oy, Porvoo, Finland, Theor. Appl. Rheol., Proc. Int. Congr. Rheol, 11th (1992), 1, 360 to 362 [2] "The influence of molecular structure on some rheological properties of polyethylene", Heino, EL, Borealis Polimers Oy, Porvoo, Finland, Annual Transactions of the Nordic Rheology Society, 1995.). [3] Definition of tenns relating to the non-ultimate mechanical properties of polymers, Pure & Appl. Chem., Volume 70, no. 3, pages 701 to 754, 1998. Microstructure quantification by NMER spectroscopy
    [00139] Quantitative nuclear magnetic resonance spectroscopy (NMR) was used to quantify the content of unsaturated groups present in the polymers.
    [00140] Quantitative 1H NMR spectra recorded in solution state using a Bruker Advance III 400 NMR spectrometer operating at 400.15 MHz. All spectra were recorded using a selective excitation probe head 10 mm optimized 13C to 125 °C using nitrogen gas for all tyres. Approximately 200 mg of material was dissolved in 1,2-tetrachloroethane-d2 (TCE-d2) using approximately 3 mg of Hostanox 03 (CAS 32509-66-3) as a stabilizer. Standard single pulse excitation was employed using a 30 degree pulse, a 10 s relaxation delay and a 10 Hz sample rotation. A total of 128 transients were acquired per spectrum using 4 simulated scans. This setting was chosen primarily for the high resolution required for quantifying the establishment and stability of the vinylidene groups.{he10a, busico05a} All chemical shifts were internally to the signal resulting from the residual protonated solvent at 5.95 ppm.
    [00141] The characteristic signals corresponding to the presence of terminal vinyl groups (R-CH=CH2) were observed and the amount of vinylidene groups quantified using the integral of the terminal protons Va and Vb coupled to 4.95, 4.98 and 5.00 and 5.05 ppm respectively considering the number of reporting sites per functional group: Nvinyl = (IVa + IVb)/2
    [00142] The content of vinyl groups was calculated as the fraction of the vinyl group in the polymer in relation to the total number of carbons present: Uvinyl = Nvinyl/Ctotal
    [00143] The characteristic signs corresponding to the presence of internal vinylidene groups (RR' C=CH2) were observed and the amount of vinylidene groups quantified using the integral of the two terminal D protons at 4.74 ppm considering the number of sites of report by functional group: Nvinylidene = ID/2
    [00144] The content of vinylidene groups was calculated as the fraction of the vinylidene group in the polymer in relation to the total number of carbons present: Uvinylidene = Nvinylidene/Ctotal
    [00145] The characteristic signs corresponding to the presence of internal cis-vinylene groups (E-RCH=CHR') were observed and the amount of cis-vinylene groups quantified using the integral of the two C protons at 5.39 ppm considering the number of reporting sites by functional group: Ncis = CI/2
    [00146] The content of the cis-vinylene groups was calculated as the fraction of the cis-vinylene group in the polymer in relation to the total number of carbons present: Ucis = Ncis/Ctotal
    [00147] The characteristic signs corresponding to the presence of internal trans-vinylene groups (Z-RCH=CHR') were observed and the amount of trans-vinylene groups quantified using the integral of the two T protons at 5.45 ppm considering the number of reporting sites by functional group: Ntrans = IT/2
    [00148] The content of trans-vinylene groups was calculated as the fraction of the trans-vinylene group in the polymer in relation to the total number of carbons present: Utrans = Ntrans/Ctotal
    [00149] The total amount of carbon was calculated from the bulk aliphatic integral between 2.85 and - 1.00 considering the number of reporting cores and compensation for sites in relation to the establishment not including in this region: Ctotal = (1 /2) * (Ialiphatic + Nvinyl + Nvinylidene + Ncis + Ntrans)
    [00150] The total amount of the unsaturated group was calculated as the sum of the individual observed unsaturated groups and thus also reported in relation to the total number of carbons present: Utotal = Uvinyl + Uvinylidene + Ucis + Utrans
    [00151] The unsaturation content is given as an amount of unsaturated group /100 kC where 100 kC means 100,000 carbons.
    [00152] The relative content of an unsaturated group (x) is reported as the fraction or percentage of a given unsaturated group in relation to the total amount of unsaturated groups: [Ux] = Ux/Utotal References he10a He, Y., Qiu, X and Zhou, Z., Mag. Res. Chem. 2010, 48, 537 to 542. busico05a Busico, V. et. al. Macromolecules, 2005, 38 (16), 6,988 to 6,996 Examples
    [00153] Low density polyethylene was produced by radical polymerization in a three-zone front feed tubular reactor. The chain transfer agent used was propylene and propionic aldehyde. The pressure in the reactor was between 200 to 250 MPa and the peak temperatures were in the range of 250 to 320 °C.
    The initiator mixture used in all experiments was composed of the following free-radical initiators (The half-life temperature of 0.1 hour (T^) given for each free-radical initiator). Initiators were dissolved in isododecane. The content of each initiator in each zone is given in Table 1.
    [00155] Initiator A (0.1 hour T^ at 75 to 90 °C in chlorobenzene), Initiator B (0.1 hour T^ at 80 to 95 °C in chlorobenzene), Initiator C (T^ 0 0.1 hour at 105 to 125 °C in chlorobenzene), Initiator D (0.1 hour T^ at 125 to 140 °C in chlorobenzene) Initiator E (0.1 hour T^ at 130 to 145 °C in chlorobenzene) ) and Initiator F (0.1 hour T4 at 155 to 175°C in chlorobenzene).

    Table 1 Material A Innovative example
    [00156] The inlet temperature of the reaction mixture in the first reaction zone (reaction zone 1) was 133 °C. About 27,000 kg/h of the reaction mixture was fed ahead of the reactor into the first reaction zone of the reactor. The initiator mixture was fed to all three reaction zones in such amounts so that the peak temperatures in Table 2 were reached. The polymerization yielded about 9,193 kg polymer/h.
    Table 2
    [00157] The chain transfer agent was added in such amounts so that the formed polymer, i.e. the low density polyethylene of the present invention, had a melt flow rate of about 5.7 g/10 min according to ISO 1133 (190°C, 2.16 kg).
    [00158] The density of the produced polymer, that is, the low density polyethylene of the present invention was about 918 kg/m3 according to ISO 1183.
    [00159] The molecular weight per weighted average (Mw) of the polymer produced, that is, the low density polyethylene of the present invention was 203,000 g/mol.
    [00160] The molecular weight distribution (MWD) of the polymer produced, that is, the low density polyethylene of the present invention was 14.5. Material B Innovative example
    [00161] The inlet temperature of the reaction mixture into the first reaction zone (reaction zone 1) was 130 °C. About 27,000 kg/h of the reaction mixture was fed ahead of the reactor into the first reaction zone of the reactor. The initiator mixture was fed to all three reaction zones in such amounts so that the peak temperatures in Table 3 were reached. The polymerization yielded about 9,320 kg polymer/h.

    Table 3
    [00162] The chain transfer agent was added in such amounts so that the formed polymer, i.e. the low density polyethylene of the present invention, had a melt flow rate of about 5.3 g/10 min according to ISO 1133 (190°C, 2.16 kg).
    [00163] The density of the produced polymer, i.e. the low density polyethylene of the present invention was about 918 kg/m3 according to ISO 1183.
    [00164] The molecular weight per weighted average (Mw) of the polymer produced, that is, the low density polyethylene of the present invention was 237,000 g/mol.
    [00165] The molecular weight distribution (MWD) of the polymer produced, ie, the low density polyethylene of the present invention was 14.8. Material C Comparative example
    [00166] The inlet temperature of the reaction mixture in the first reaction zone (reaction zone 1) was 135 °C. About 27,000 kg/h of the reaction mixture was fed ahead of the reactor into the first reaction zone of the reactor. The initiator mixture was fed to all three reaction zones in such amounts so that the peak temperatures in Table 4 were reached. The polymerization yielded about 9,220 kg polymer/h.
    Table 4
    [00167] The chain transfer agent was added in such amounts so that the formed polymer had a melt flow rate of about 3.0 g/10 min in accordance with ISO 1133 (190 °C, 2.16 kg).
    [00168] The density of the polymer produced was about 918 kg/m3 according to ISO 1183.
    The molecular weight per weighted average Mw was 180,000 g/mol.
    [00170] The molecular weight distribution (MWD) was 21.1. Material D Comparative example
    [00171] The inlet temperature of the reaction mixture into the first reaction zone (reaction zone 1) was 135 °C. About 27,000 kg/h of the reaction mixture was fed ahead of the reactor into the first reaction zone of the reactor. The initiator mixture was fed to all three reaction zones in such amounts so that the peak temperatures in Table 5 were reached. The polymerization yielded about 9,210 kg polymer/h.
    Table 5
    [00172] The chain transfer agent was added in such amounts so that the formed polymer had a melt flow rate of about 4.0 g/10 min in accordance with ISO 1133 (190 °C, 2.16 kg).
    [00173] The density of the polymer produced was about 918 kg/m3 according to ISO 1183.
    The molecular weight per weighted average Mw was 170,000 g/mol.
    [00175] The molecular weight distribution (MWD) was 19.4. Material E Comparative example
    [00176] The inlet temperature of the reaction mixture into the first reaction zone (reaction zone 1) was 135 °C. About 27,000 kg/h of ethylene, ie the reaction mixture, was fed to the front of the reactor, ie into the first reaction zone of the reactor. The initiator mixture was fed to all three reaction zones in such amounts that the peak temperatures in Table 6 were reached. The polymerization yielded about 9,180 kg polymer/h.
    Table 6
    [00177] The chain transfer agent was added in such amounts so that the formed polymer had a melt flow rate of about 4.0 g/10 min in accordance with ISO 1133 (190 °C, 2.16 kg).
    [00178] The density of the polymer produced was about 918 kg/m3 according to ISO 1183.
    [00179] The molecular weight per weighted average Mw was 167,000 g/mol.
    [00180] The molecular weight distribution (MWD) was 22.6.
    [00181] The storage modulus G', measured in a loss modulus G" of 5 kPa, of the low density polyethylene of the present invention, i.e. Material A and B, is larger than the comparative examples, for example , Material D to E, produced with higher inlet temperatures. From the examples, see Table 7 and Figure 1, it is also clear that the narrowing is reduced by increasing G' (5 kPa) By increasing G' ( 5 kPa) by reducing only the MFR (Material C), the processing properties (Edge interlacing) become so poor that it is impossible to run at 400 m/min (Table 7)
    [00182] Figure 2 shows the importance of a low inlet temperature in the first reaction zone of the reactor to obtain a high weighted average molecular weight (Mw) and, therefore, a low narrowing. The importance of the combination of high Mw and low MFR is shown in Table 7 where the MFR C material is not possible to rotate at high line speeds. Table 8 and Figure 4 show the innovative exemplary Material A and B compared to commercially available LDPE versus MFR and Mw.
    [00183] In Table 7 and Figure 2, the improvement in the properties of narrowing by having a larger Mw is clear. Also from example C, it is clear that achieving a high Mw by lowering the MFR generates poor processing properties where the material cannot be run at high line speeds. As seen in Figure 1, the elastic index is important to improve the taper, but as for Mw, reducing the MFR to increase the elastic index does not yield the desired processing properties.
    Table 7 Example Extrusion Coating Test
    [00184] Extrusion coating runs were made on the Beloit coextrusion coating line. It had Peter Cloeren's EBR matrix and a five-layer power pack. The line array aperture width was 850 to 1000 mm, the maximum substrate width is 800 mm and the line speed was kept at 100 m/min.
    [00185] The extrusion coating behavior of polymer compositions, ie, Materials A, B, C, D and E were analyzed.
    [00186] In the above coating line Kraft UG paper which has a basis weight of 70 g/m2 was coated with a layer of a polymer composition according to the present invention which has a basis weight of 10 g/m2. The polymer composition melt temperature, i.e., the melt of Material A, B, C, D or E, was set at 320°C.
    [00187] The performance of stretch tests of the materials, that is, Materials A, B, C, D and E was performed by increasing the line speed gradually until the web instability occurred. The coating weight (amount of polymer on the substrate in g/m2) was kept at 10 g/m2. The mat instability was monitored through the amount of edge interlacing. Samples were marked on the coated mat at intervals of 100 m/min, starting at 100 m/min until mat instability occurred. Samples were taken from the spool and the nip and coating weight were measured later. Narrowing is defined as the difference in the width of the die opening and the width of the substrate coating. Coating weight was measured from 5 positions along the mat.
    权利要求:
    Claims (11)
    [0001]
    1. Low density polyethylene characterized by the fact that it has a molecular weight distribution Mw/Mn that is 11 to 14.8, a storage modulus G', measured at a loss modulus G" of 5 kPa, which is above 3,000 Pa, a weighted average molecular weight (Mw) that is between 192,000 and 250,000 g/mol and has a melt flow index (MFR) in accordance with ISO 1133 (190 °C, 2.16 kg) which is higher than 3.0 g/10 min.
    [0002]
    2. Low density polyethylene, according to claim 1, characterized in that the low density polyethylene is produced in a tubular reactor.
    [0003]
    3. Low density polyethylene according to claim 1 or 2, characterized in that the low density polyethylene has a vinylidene content that is at least 15/100 kC.
    [0004]
    4. Composition comprising low density polyethylene as defined in any one of claims 1 to 3, characterized in that it may comprise low density polyethylene in an amount of 5 to 40% by weight, based on the total weight of the composition and may further comprise at least one olefin polymer prepared in the presence of a transition metal catalyst, which at least one olefin polymer may be selected from polyethylene, polypropylene or poly-1-butene homoor copolymers.
    [0005]
    5. Process for the production of low density polyethylene, as defined in any one of claims 1 to 3, in a tubular reactor by radical initiated polymerization under high pressure in which the polymerization is carried out through the reaction of a reaction mixture, which comprises ethylene monomers, under the action of one or more radical initiators, such as peroxides, oxygen or combinations thereof, characterized by the fact that the inlet temperature of the reaction mixture in the first reaction zone of the reactor is 125 to 132°C.
    [0006]
    6. Process according to claim 5, characterized in that a cocktail of radical initiator is used, which is composed of the following radical initiators, wherein the half-life temperature of 0.1 hour (T^) is given for each radical initiator: Initiator A (0.1 hour T^ at 75 to 90°C in chlorobenzene), Initiator B (0.1 hour T^ at 80 to 95°C in chlorobenzene), Initiator C (T ^ 0.1 hour in 105 to 125 °C in chlorobenzene), Initiator D (T^ 0.1 hour in 125 to 140 °C in chlorobenzene), Initiator E (T^ 0.1 hour in 130 to 145 °C in chlorobenzene) and Initiator F (T4 0.1 hour at 155 to 175 °C in chlorobenzene).
    [0007]
    7. Low density polyethylene characterized by the fact that it is obtainable by the process as defined in claim 5 or 6.
    [0008]
    8. Method for an extrusion coating process, the method being characterized in that it comprises extrusion coating a flat substrate by extruding low density polyethylene as defined in any one of claims 1 to 3, or composition as defined in claim 4, in a molten state through a flat die on said substrate or method for an extrusion lamination process using low density polyethylene as defined in any one of claims 1 to 3, or the composition as defined in claim 4.
    [0009]
    9. Article, for example, an extrusion article, extrusion coating article, extrusion laminating article, film blowing article, film casting article, wire and cable extrusion article, injection molding article, blow molding article or tube extrusion article, characterized in that it comprises low density polyethylene as defined in any one of claims 1 to 3, or composition as defined in claim 4.
    [0010]
    10. Use of a low density polyethylene as defined in any one of claims 1 to 3, characterized in that it is performed in extrusion coating, extrusion lamination, film blowing, film casting, wire and cable extrusion , injection molding, blow molding or tube extrusion.
    [0011]
    11. Use of a composition as defined in claim 4, characterized in that it is performed in extrusion coating, extrusion lamination, film blowing, film casting, wire and cable extrusion, injection molding, blow molding or tube extrusion.
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    同族专利:
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    法律状态:
    2020-03-17| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-01-05| B06A| Patent application procedure suspended [chapter 6.1 patent gazette]|
    2021-05-25| B07A| Application suspended after technical examination (opinion) [chapter 7.1 patent gazette]|
    2021-07-06| B07B| Technical examination (opinion): publication cancelled [chapter 7.2 patent gazette]|
    2021-07-20| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-08-31| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 07/12/2012, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    EP12170203.9|2012-05-31|
    EP12170203|2012-05-31|
    PCT/EP2012/005072|WO2013178242A1|2012-05-31|2012-12-07|Low density polyethylene for extrusion coating|
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