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    • 专利摘要:
    LOW DENSITY POLYETHYLENE (LDPE) OBTAINED UNDER HIGH PRESSURE FOR MEDICAL APPLICATIONS, PROCESS OF MANUFACTURING THE SAME, ITS USE AND MOLDED ARTICLE. The present invention relates to an innovative polymerization of an unusual LDPE at high pressure from radicals.
    公开号:BR112012010892B1
    申请号:R112012010892-1
    申请日:2010-11-10
    公开日:2021-07-06
    发明作者:Gerd Mannebach；Cathrine Beuzelin；Christian-Ulrich Schmidt；Thomas Maurer；Jörn Müller；Alexander Wörz；Mike Freudenstein
    申请人:Basell Polyolefine Gmbh；
    IPC主号:
    专利说明:

    The present invention relates to the field of medical packaging. It claims an unusual low-density polyethylene (LDPE), radically polymerized, suitable for manufacturing sterilizable sealable bottles and containers for, for example, liquids.
    Medicinal liquids for use in infusion or injection are usually filled in plastic containers by a process known as BFS: blow/fill/seal. An important feature of the blow/fill/seal process is the sterile, pyrogen-free molding of vials or ampoules directly from polyethylene (PE) or polypropylene (PP) extruded into cooled blow molds with immediate sterile filling of the product, and then a one-step hermetic sealing of the container, and most importantly, under aseptic conditions on the same machine promptly, without delay. The technology is ultimately known to be neutral as to the nature of the filling product. These sealed vials or ampoules made of flexible polymer need to be subsequently further thermally sterilized, namely by subjecting the sealed filled vials for an extended period of at least 30 min to a temperature of about 115-121°C in saturated water vapor in an autoclave tank. in the case of sensitive substances, schemes with lower temperatures apply, eg dextrose solutions included in most medical infusion formulations cannot withstand 121°C and must be sterilized at 115.5°C for 30 min. However, even this lower temperature limit may not be reached with known PE materials, requiring even lower sterilization temperatures closer to 110°C and consequently much longer sterilization times.
    The temperature/softening resistance and melting temperatures of the LDPE material used are paramount to not leaking from the vial during sterilization because of the build-up of internal pressure at least during the initial heating phase of the sterilization process, and they need further improvement. The PE materials sought are those that similarly allow for faster rise in sterilization temperature and/or use higher sterilization temperatures, to shorten sterilization process times in manufacturing, and at the same time, preferably, retain excellent processability of the polymer for blow molding concomitantly. It has not been feasible to design such material by prior art.
    It is an object of the present invention to devise a new LDPE material and consequently a new process for its manufacture, where said new material allows faster thermal sterilization and/or sterilization at a higher temperature than the materials of the previous techniques, and at the same maintaining good processability in terms of a sufficiently high melt flow rate. This objective was solved by a new LDPE material which has a higher density corresponding to higher crystallinity and a higher melting temperature, respectively, and at the same time, surprisingly, retaining the comparatively high melt index of prior art materials. This material was not previously known. Until now, their combination of properties simply could not be achieved by known manufacturing processes.
    According to the present invention, for the first time a low density polyethylene (LDPE) is conceived obtained by the polymerization of ethylene with free radicals, and where LDPE is a homopolymer, which LDPE has a density of at least 0.932 g/ cm3 or more, preferably at least 0.933 g/cm3 or more, and which has a molecular weight distribution (polydispersion) Mw/Mn of between 6 and 15, and has an Ml (190°C/2.16 kg) > 0. 45 g/10 min, preferably > 0.80 g/10 min, more preferably > 0.90 g/10 min.
    According to the present invention, a low-density polyethylene (LDPE) is designed, preferably, for use in blow molding/filling/sealing, obtained by radical polymerization of ethylene free, which LDPE has a density of at least 0.932 g/cm3 or more, preferably at least 0.933 g/cm3 or more, has a molecular weight distribution Mw/Mn between 3 and 10, and has an Ml (190°C /2.16 kg) > 0.45 g/10 min, preferably > 0.80 g/10 min, more preferably > 0.90 g/10 min.
    Preferably, the melt index or Ml (190°C/2.16 kg) reaches, in combination with the lower limit given above for the same, up to 1.5 g/10 min, more preferably up to 1.25 g/ 10 min, and most preferably up to 1.1 g/10 min.
    The LDPE of the invention is typically and preferably a homopolymer. Preferably, the LDPE of the invention encompasses carbonyl groups or even distinct alkyl residues due to a chain transfer agent used during radical polymerization, and this chain transfer agent is selected from the group consisting of aldehyde or alkane from C3 to C10, preferably a C3 to C15 alkane comprising a tertiary or secondary CH group. More preferably, the chain transfer agent is a C3 to C6 aldehyde, and most preferably is propanal.
    Preferably, the density of the LDPE of the invention is between 0.932 and 0.936 g/cm3, more preferably between 0.932 and 0.935 g/cm3 and most preferably between 0.933 and 0.934 g/cm3. The above-mentioned preferred density ranges apply particularly in combination with the above-mentioned preferred ranges for the melt index limits or Ml (190°C/2.16 kg), particularly reaching a melt index of at least >0.80 g /10 min and up to 1.25 g/10 min.
    Preferably, the LDPE has a melting temperature at DSC > 118°C. For measurement details, see the method description given in the experimental section. Typically, the LDPE of the present invention has a peak in DSC. Said peak, defined as the 2-peak temperature of the heat of fusion (Tm2), is in a temperature range between 118°C and 122°C, preferably it falls in a range between 119°C and 120°C .
    The molecular weight distribution (MWD) of the LDPE of the invention is preferably, in the typical way of practicing the invention, at least substantially monomodal, in terms of the number of peaks corresponding to the optimum values of the true curve, and preferably has the value of aforementioned comparatively narrow polydispersion of MWD preferably reaching up to 10.
    Preferably, the LDPE has a weight average molecular weight (Mw) of between 60,000 and 130,000 g/mol, preferably between 80,000 and 120,000 g/mol. It is important to note that Mw is determined by gel permeation chromatography (GPC) employing light scattering detection and quantification, responsive to the LCB contents of the present LDPE. The method is spelled out in more detail in the experimental section.
    Most preferably, the Vicat A temperature of the LDPE of the present invention is in the range between 109 and 112°C. - The softening or Vicat temperature is dependent on the melting temperature determined by DSC, and changes linearly with it in the relevant ranges in the present context. Therefore, the melting temperature itself is already indicative of a correspondingly lower Vicat temperature.
    Preferably, the zero shear viscosity r|0 of the LDPE of the present invention is < 9 * 104 Pas, more preferably it is < 7 * 104 Pas, where q is the zero shear viscosity < 190°C determined by the rule of thumb of Cox-Merz @190°C from complex viscosity measurement. The complex viscosity rf <190°C can be determined by dynamic shear (sinusoidal) of a polymer sample, for example, in a two-plate rheometer such as Anton-Paar MCR 300 (Anton Paar GmbH, Graz/Austria) as described very detailed in the experimental section. According to the Cox-Merz Rule, when the rotational velocity w is expressed in radiant units, at low shear rates, the numerical value of q* is equal to that of the conventional intrinsic viscosity, based on low-shear capillary measurements. Those skilled in the art of rheology are familiar with determining zero-shear viscosity in this way (Cox et al., 1958, J. Polymer Science 28, 619).
    The LDPE material of the invention, in addition to having the highest density and the highest melting temperature in DSC together with a comparatively high melt index (Ml) (190/2.16), allows it particularly to be used in applications of blow molding, especially BFS applications. Blow moldings, particularly sealed vials or ampoules, more preferably vials or ampoules with a volume between 0.001 L and 10 L, manufactured from or comprising the LDPE of the present invention are another object of the present invention. Similarly, another object of this invention is an innovative and ingenious process that allows for the first time to produce this unusual LDPE polymer. The LDPE of the present invention stands out further for its excellent E-module characteristic, and furthermore the reduced tendency of the material to soften under heating, it is therefore important to avoid leakage from the sealed bottles during sterilization and change of pressurization of the used autoclave tanks . In addition, it enables easier processing in blow molding applications due to a lower complex zero shear viscosity q0 compared to comparable prior art materials with even lower density. The new LDPE material furthermore preserves or even gradually improves the acceptable expansion ratio of comparable materials from prior art, which is relevant for blow molding applications.
    According to another object of the invention, a process is claimed for manufacturing the LDPE or LDPEs according to the present invention, distinguished by the fact that it comprises the steps of conducting high pressure polymerization of ethylene, I. adding to a tubular reactor that has at least three consecutive reaction zones, as defined by the number of available reagent inputs, rather than a tubular reactor that has only three reaction zones, in a first input to the first reactor zone, a mixture of peroxides comprising at least a first peroxide which has a half decay time < 0.1 h at 105°C and further comprising a second peroxide which has a half decay time >0.1 h at 105°C . II. adding to said reactor at a second inlet, and at any other available inlet, a peroxide mixture consisting essentially of at least one second peroxide that has a half decay time >0.1 h at 105°C in chlorobenzene, which can be the same as or different from the second peroxide used in step I), III. collect the polyethylene product from the reactor.
    The half-decay time is determined in mono-chlorobenzene according to the generally recognized "accumulated heat storage test" as indicated in the "United Nations Transport of Hazardous Goods Recommendation", Manual of Tests and Criteria, New York and Geneva. From the above, it should be understood that the terms "first peroxide" and "second peroxide" belong to the generic classes of peroxides that meet the definition of respective half decay time for each class given above.
    More preferably, the above process is to be understood with the proviso that all peroxide initiators used, the first and also the second, have a half-life temperature in 1 min between 80°C and 160°C. Those skilled in these techniques should often refer to the half-life temperature simply as "half-life" which is the temperature at which half of the peroxide will decompose in an amount of time that is in precisely 1 minute in precisely the present context. Routinely, the above techniques may refer to half-life as well as commonly referring to a base period of 10 hours or one hour; in the present context, however, half-life should be understood to refer to a 1-minute reference period. Typically, the half-life of peroxides is reported on a semi-log plot Arrhenius versus temperature.
    The operation of the tubular reactor for polymerization with ethylene radicals is known. A particularly suitable comprehensive description of the design and operation of tubular reactors can be found, for example, in WO 01/60875 and in "Ullmans Encylopaedie der technischen Chemie", Verlag Chemie GmbH, Weinheim/Germany, Volume 19 (1980 ), pages 169-178, incorporated herein by reference. It is particularly preferred that a tubular reactor according to the present invention has a design as provided and preferred in said WO 01/60875. After start-up, polymerization is highly exothermic, and therefore, strict control of the maximum or peak temperature is required. The internal profile of the reactor may be relevant, as described in WO 05/065818. The initiator is metered repeatedly along the length of the reactor tube, at different inlets that designate different reaction zones over the entire length of the reactor tube. The initiator peroxide is usually dosed in the range between 0.5 and 100 ppm (by weight). Prior to injection of highly compressed ethylene gas into the reactor space, it is important to prevent premature polymerization triggered by the mass balance of ethylene and comonomer when present in the compression stage. It is possible and preferred, therefore, to add stabilizers, differently termed inhibitors, such as sterically hindered amines or mixtures thereof, to the gaseous monomer as particularly described, for example, in documents no. DE-196 22 441 and WO 01/60875, of preferably in amounts <50 ppm. Inhibitors can therefore be dosed as a solution in an aliphatic organic solvent such as isodecane, in the compression stage before the reaction stage. It is also possible, however, to use other stable radicals such as NO or O2. Especially with oxygen, lower concentrations <10ppm oxygen, preferably <5ppm oxygen may be sufficient to allow a sufficient inhibitory effect in the compression stage, at temperatures below 170°C, without becoming a separate initiator molecule from a dose-triggered manner at the highest temperatures prevalent in the reactor space. Oxygen initiation would require a higher oxygen concentration of at least 20 ppm in the reactor space; in accordance with the present invention, it is decisively preferred not to have or to have at least <10 ppm oxygen in the tubular reactor or reactor space during polymerization. This operating mode of the polymerization process is described in US Patent No. 5,100,978, incorporated herein by reference, including the sudden rise and fall of the reactor temperature between the injection nozzles to designate. The minimum temperature to start the polymerization reaction is between 125°C and 170°C, preferably in the range between 135°C and 150°C. Concomitantly, it is important to control the reactor temperature during the exothermic polymerization so that it remains < 230°C in the present context. In accordance with the present invention, it is further preferred to use a chain transfer reagent during polymerization to control the average chain length of the polyethylene. The terms "chain transfer reagent" and "mass transfer reagent" are used hereinafter interchangeably for the purposes of the invention. As with any starter compound, this mass transfer reagent is involved in starting the radical polymerization and is incorporated into the product. Appropriate mass transfer reagents can be, for example, dialkyl ketones, alkanal or alkenes. Examples are MEK (metal ethyl ketone), 1-propanal or isopropane. Preferably such chain transfer or mass transfer reagent is selected from the group consisting of aldehydes from C3 to C10 or alkanes from C3 to C10, more preferably aldehydes from C3 to C10 and/or branched alkanes from C3 to C10. Most preferably, 1-propanal is used.
    The notion of "LDPE homopolymer", in the context of the present invention and in accordance with a particularly preferred embodiment for the product of the present invention, correspondingly defines a low density polyethylene homopolymer including only trace amounts of impurities from other olefins recognized routinely in the industrially produced ethylene. Consequently, the LDPE homopolymer of the invention does not have the presence of olefinic comonomers at >0.5% by weight, based on the total weight of the LDPE, more preferably >0.1% by weight of said amounts going beyond normal traces of olefinic impurities usually carried by ethylene fed from industrial crackers. The presence or absence of these impurities can be determined by C-13 NMR analysis, as is routinely known to those skilled in these techniques. The term "LDPE homopolymer" is inclusive; in contrast to the presence of integral molecular clusters in the final polymeric product deriving from the initiator and/or mass transfer reagents. Similar considerations apply to the incorporation of oxygen, when it is being used deliberately as an initiator and when possibly present only in minimal amounts, that is, when used primarily in a dose-controlled manner, but as an inhibitor, as noted above.
    In addition, it is possible that the solvent used to solubilize the initiators functions as a mass transfer reagent during polymerization. However, any mass transfer reagent, especially alkanes not being distinguishable from the comonomer itself once incorporated into the product present in the reactor is preferably dosed in the amount <100ppm, more preferably <50ppm, and most preferably < 15 ppm, and thus, may not compromise the preferred threshold level given above for comonomer-derived or comonomer-like impurities in the final product.
    The time-consuming sterilization procedure for blow/fill/seal (BFS) PE packaging is in fact a speed-limiting step in production. The increase in melting temperature and softening of the present LDPE material alone translates into a huge n0% reduction in sterilization time from 150 min to 49 min for BFS articles such as, for example, infusion bottles such as exemplified in Figure 4. Other advantages are greater confidence in sterilization, better embossing of these BFS articles, and further reduction in energy and weight, allowing BFS articles with reduced wall thickness to be manufactured. Experimental Section
    GPC-MALLS measurements to determine Mw were conducted on a PL-GPC C210 instrument from Polymer Laboratories, according to ISO16014-1.2.4:2003 on GPC in high temperature polyethylene under the following conditions: styrene column /divinylbenzene, 1,2,4- trichlorobenzene (TCB) as solvent, flow rate 0.6 mL/min, at 135°C, with detection by multi-angle laser light scattering detector (MALLS). Polyethylene (PE) solutions with concentrations of 1 to 5 mg/10 mL, depending on the samples, were prepared at 150°C for 2-4 hours before being transferred to SEC injection vials seated in a carousel heated to 135 °C. Polymer concentration was determined with infrared detection by a PolymerChar IR4 detector and light scatter was measured with a MALLS Wyatt Dawn EOS multi-angle detector (Wyatt Technology, Santa Barbara, CA). A 120 mW laser source with a wavelength of 658 nm was used. The specific refractive index was considered as 0.104 mL/g. Data evaluation was performed using Wyatt ASTRA 4.7.3 and CORONA 1.4 software.
    The amplitude of the molar mass distribution (MWD) or polydispersion is defined as Mw/Mn. The definition of Mw, Mn, Mz, MWD can be found in the "Handbook of PE", editor A. Peacock, pages 7-10, Marcel Dekker Inc., New York/Basel 2000. The determination of Mn and Mw/Mn calculated from this (and from Mw obtained by the method other than GPC with light scattering described above) was conducted by high temperature gel permeation chromatography, using a method described essentially in DlN 55672-1:1995-02 (February 1995 issue). The modifications when following the DIN standard are as follows: Solvent 1,2,4-trichlorobenzene (TCB), device temperature and solutions 135°C and as concentration detector an IR-4 infrared detector from PolymerChar (Valencia, Paterna 46980 , Spain), for use compatible with TCB.
    A WATERS Alliance 2000 equipped with the following SHODEX UT-G guard column and serially connected SHODEX UT 806 M (3x) and SHODEX UT 807 separation columns was used. The solvent was vacuum distilled under nitrogen and stabilized with 0.025% by weight of 2,6-di-t-butyl-4-methyl-phenol. The flow rate used was 1 mL/min, the injection was 500 μL and the polymer concentration was in the range between > 0.01% and < 0.05% in weight. Molecular weight calibration was established using polystyrene monodispersed (PS) standards from Polymer Laboratories (now Varian, Inc., Essex Road, Church Stretton, Shropshire, SY6 6AX, UK) in the range between 580 g/mol and 11,600 .000 g/mol to additionally hexadecane. The calibration curve was then fitted to polyethylene (PE) by means of the Universal Calibration method (Benoit H., Rempp P. and Grubisic Z., in J. Polymer Sci., Phys. Ed., 5:753 (1967)) ). The Mark-Houwing parameters used for this were for PS: kPS = 0.000121 dL/g, aPS = 0.706 and for PE kPE = 0.000406 dl_/g, aPE = 0.725, valid in TCB at 135°C. Data recording, calibration and calculation were conducted using NTGPC_Control_V6.02.03 and NTGPC_V6.4.24 (HS -Entwicklungsgesellschaft für wissenschaftliche Hard- und Software mbH, HauptstraBe 36, D-55437 Ober-Hilbersheim) respectively. Still relevant to smooth and convenient processing at low pressure, preferably, the amount of polyethylene of the invention with a molar mass < 1 Mio. g/mol, determined by GPC for determination of molecular weight distribution standards is preferably , above 95.5% by weight. This is determined in the usual course of measuring the molar mass distribution by applying the WIN-GPC software from the company "HS-Entwicklungsgesellschaft für wissenschaftliche Hard-und Software mbH", Ober-Hilbersheim/Germany, see above.
    The expansion (expansion ratio) was determined in accordance with ISO 11443-1995, cp. section 7.8 on "Measuring Extruded Expansion".
    The modulus of elasticity E was measured according to ISO 527-1 and -2 (rod type 1A, 1 mm/min and secant modulus between 0.05% and 0.25% elongation on a compression molded sample plate , obtained according to ISO 1872-2 of granulated LDPE as collected from the reactor).
    Density was determined in accordance with ISO 1183.
    Vicat temperature was determined using ISO 306:2004, method A50.
    The melt flow index (Ml) was determined in accordance with ISO 1133-2005 at a temperature of 190°C and a load of 2.16 kg (Ml) or 21.6 kg (HLMI), as indicated.
    DSC was conducted to determine the melting point temperature Tm (i.e. 2-heat melting temperature, Tm2). Polymer melting enthalpies (ΔHf) were measured by Differential Calorimetry of
    Scan (DSC) on a heat flow DSC (TA-lnstruments Q2000), according to the method of the standard (ISO 11357-3 (1999)). The sample holder, an aluminum container, is loaded with 5 to 6 mg of the specimen and sealed. The sample is then heated from room temperature to 200°C with a heating rate of 20 K/min (first heat). After a retention time of 5 minutes at 200°C, which allows for complete melting of the crystallites, the sample is cooled to -10°C with a cooling rate of 20 K/min and held at this temperature for 2 minutes. Finally, the sample is heated from -10°C to 200°C with a heating rate of 20 K/min (second heating). After construction of a baseline, the area under the peak of the second heat run is measured and the enthalpy of fusion (ΔHf) in J/g is calculated according to the corresponding ISO standard (11357-3 (1999)) .
    Dynamic viscosity measurement is conducted to determine the complex viscosity q*. The measurement is made by dynamic (sinusoidal) deformation of the polymer blend in a two-plate rheometer such as the Anton-Paar MCR 300 (Anton Paar GmbH, Graz/Austria). First, the sample (in granulated or powdered form) is prepared for measurement as follows: 2.2 g of material is weighed and used to fill a 70 x 40 x 1mm molding plate. The dish is placed in a press and heated to 200°C for 1min under a pressure of 20-30 bar. After the temperature of 200°C is reached, the sample is pressed at 100 bar for 4 min. After the end of the pressing time, the material is cooled to room temperature and the plates are removed from the form. A visual quality control test is performed on the pressed plates for possible cracks, impurities or lack of homogeneity. Polymer disks with a diameter of 25 mm and a thickness of 0.8-1 mm are cut from the pressed form and introduced into the rheometer for the measurement of dynamic mechanical analysis (or frequency scanning).
    The measurement of the elastic (G1) and viscous (G") moduli and the complex viscosity q* as a function of frequency is carried out in an Anton Paar MCR300 tension-controlled rotary rheometer, as mentioned above.
    The device is equipped with plate-to-plate geometry, that is, two parallel discs with a radius of 24.975 mm each with a standard spacing of 1000 mm between them. For this clearance, -0.5 mL of sample is loaded and heated to the measuring temperature (default for PE: T = 190°C). The molten sample is kept at the test temperature for 5 min to achieve a homogeneous fusion. After that, the frequency sweep begins with the instrument taking the points between 0.01 and 628 rad/s logarithmically.
    A periodic deformation in the linear range with a load amplitude of 0.05 (or 5%) is applied. The frequency is varied starting at 628.3 rad/s (or -100 Hz) up to 8.55 rad/s and for the very low frequency regime continuing from 4.631 rad/s to 0.01 rad/s (or 0.00159 Hz) with an increased sampling rate such that more points are taken for the low frequency range.
    The resulting shear stress amplitude and phase lag from the applied strain are obtained and used to calculate modulus and complex viscosity as a function of frequency.
    The points are chosen from the range of logarithmically descending frequencies from the high to the low frequencies and the result at each frequency point is displayed after at least 2-3 oscillations with a stable measured value are obtained. Generic Description of the Polymerization Process
    The present invention relates to the production of low density polyethylene (LDPE) with a low melt index. The product is synthesized via the high pressure ethyl polymerization process in a tubular reactor, known as the patented Lupotech TS™ process, using propionaldehyde as a chain transfer agent, and peroxide cocktails as free radical initiators. The reactor had a water jacket to allow for temperature control, especially peak temperature control in the different zones of the reactor.
    The tubular reactor used for the different examples has the following characteristics: • Three reactor zones (length of each: 387 m - 413 m-232 m) • Total reactor length: 1032 m • Tube inner diameter: 40 mm • Residence time in the tubular reactor: 75 s • All gas coming from the gas feed compressor enters the front of the preheater/reactor • The reactor is monitored by thermocouples installed at regular intervals along the tubular reactor.
    Different peroxide cocktails, diluted in isododecane, are prepared and fed into each reactor zone.
    Taking into account the relative inlet position and the maximum temperature in each zone, the selected peroxides used are listed here (trademark Trigonox®, supplier: AkzoNobel, A-mersfoort/Netherlands): TBPND: t-butyl peroxy-neodecanoate, 75% pure in aliphatic hydrocarbon solvent, CAS No. 26748-41-4 TBPPI: t-butyl peroxypivalate, 25% pure in aliphatic hydrocarbon solvent, CAS No. 927-07-1 TBPEH: peroxy-2-ethylhexanoate t-butyl, 70% pure in aliphatic hydrocarbon solvent, CAS No. 3006-82-4 TBPIN: t-butyl peroxy-3,5,5-trimethylhexanoate, 30% pure in aliphatic hydrocarbon solvent, CAS No. 13122-18 -4
    To limit reactor fouling, the reactor pressure is lowered at regular intervals, regulated by the relief valve. Subsequent to passing through the last zone of the reactor zone, the mixture of polyethylene and unconverted ethylene gas is discharged and also expanded through the relief valve at the end of the reactor tube, which reduces the pressure level to the inlet pressure of the heat exchanger closer to 300 bar. Concomitantly with the passage through the relief valve, due to the Joule Thomson effect, the temperature of the mixture decreases by several tens, depending on the reactor pressure, the reactor exit temperature and the specific degrees of polymer produced.
    After the relief valve, the mixture is then first cooled in a heat exchanger, called an aftercooler, before entering the high pressure product separator (HPPS), where the molten polymer is separated from the unreacted ethylene. Normal HPPS pressure is around 300 bar. At this stage, the unreacted ethylene is broken down and is preferably used to feed a high pressure recycling loop which includes additional purification steps. The molten product retained in the HPPS, always containing dissolved/absorbed ethylene, is expanded again to the inlet pressure of the low pressure separator (LPPS), where it is rid of said residual ethylene. The LPPS pressure is in the range between 0.5 and 4 bar, and is normally maintained between 0.5 and 2.5 bar. The LPPS melt output is directly connected to the extruder inlet via a gate valve. The extruder for discharging the final LDPE polymer material is a single-screw Pomini, with a subsequent degassing. Its matrix plate is heated with high pressure water vapor. The granulated LDPE thus produced was subjected to chemical and mechanical tests as described in the sections below. A typical temperature profile for reactor operation for the present invention is illustrated in Figure 1. Note that the temperature probes are evenly distributed over the entire length of the reactor described above, and thus correspond to the distance between the input. the reactor and the discharge of the gas supply compressor. The comparative example is a high pressure LDPE Lupolen 3220 F (commercially available from Basell Polyolefine GmbH, Germany, with density of 0.930 g/cm3 and Ml 2.16 kg = 0.77), ie obtained by radical polymerization. It is used as a comparative example in the entire Figure 1-4. Example 1:
    The polymerization was operated as generically described above, with the following particularities: • Reactor pressure at the gas feed compressor discharge: 3,055 bar • Preheater outlet temperature = 139°C • Propionaldehyde flow = 20 L/h • Temperature maximum in each zone: 225°C/235°C/235°C
    The composition of the peroxide cocktails for each of the three zones is indicated in Table I below: Table I

    Taking into account the temperature at the entrance to zones 2 and 3, the TBPND and TBPPI are not required. The product thus obtained was characterized as follows: • Density: 933.6 kg/m3 • Ml : 0.94 g/10min (190°C/2.16 kg) • Production rate = 5.4 t/h, representing about 18% conversion rate • Mw (weight average molecular weight) = 123,061 g/mol • Mn (numerical average molecular weight) = 12,340 g/mol • Melting temperature: 119°C • E modulus: 487 MPa • Expansion ratio: 82% Example 2:
    The polymerization was operated again as generically described above in the preamble of the experiments, again with the following modifications: • Reactor pressure at the discharge of the gas feed compressor: 3,055 bar • Preheater outlet temperature = 139°C • Propionaldehyde flow rate = 18 L/h • Maximum temperature in each zone: 212°C/2250C/222°C
    The composition of the peroxide cocktails for the three zones is shown in Table II below: Table II

    Taking into account the low Tmax in zone 1, there is no longer any interest in using TBPIN. • as above in Example 1, taking into account the temperature at the entrance to zones 2 and 3, the TBPND and TBPPI are not required. The product thus obtained was characterized as follows: • Density: 934.5 kg/m3 • Ml: 0.94 g/10 min (190°C/2.16 kg) • Production rate = 5.1 t/h , representing 17% conversion rate • Mw (weight average molecular weight) = 99,365 g/mol • Mn (number average molecular weight) = 17,959 g/mol • Melting temperature: 120°C • E modulus: 525 MPa • Ratio of expansion: 80%
    The GPC, rheological data and DSC, respectively, are indicated in Figures 2 and 3 for the products of Examples 1 and 2, compared to the lower density product available from prior art (sold by the present applicant, Lupolen 3220 D ). Figure 2 depicts the dynamic viscosity at different low shear rates. Figure 3 illustrates the DSC caloric data. Example 3:
    The polymerization was operated again as generically described above in the preamble of the experiments, again with the following modifications: • Reactor pressure at the discharge of the gas feed compressor: 3,055 bar • Preheater outlet temperature = 139°C • Propionaldehyde flow rate = 16 L/h • Maximum temperature in each zone: 216°C/220°C/220°C • The composition of the peroxide cocktails for the three zones is indicated in Table III below: Table III

    The resulting product had the following characteristics: • Density: 933.5 kg/m3 • Ml: 0.48 g/10 min (190°C/2.16 kg ) • Production rate = 5.1 t/h represented 17 % conversion rate • Mw (weight average molecular weight) = 107.248 g/mol • Mn (number average molecular weight) = 23.618 g/mol • Melting temperature: 119°C • E modulus: 500 MPa • Expansion ratio: 76% Example 4:
    The polymerization was operated again as generically described above in the preamble of the experiments, again with the following modifications: • Reactor pressure at the gas feed compressor discharge: 3,120 bar • Preheater outlet temperature = 139°C • Propionaldehyde flow = 16.5 L/h • Maximum temperature in each zone: 206°C/215°C/215°C • The composition of the peroxide cocktails for the three zones is indicated in Table IV below: Table IV

    The resulting product had the following characteristics: • Density: 934.3 kg/m3 • Ml: 0.51/10 min (190°C/2.16 kg) • Production rate = 4.7 t/h representing 15, 5% conversion rate • Mw (weight average molecular weight) = 104,608 g/mol • Mn (number average molecular weight) = 23,856 g/mol • Melting temperature: 120°C • E modulus: 519 MPa • Expansion ratio : 75%
    Examples 3 and 4 demonstrate that it is possible to obtain similar melting temperatures, albeit with lower Ml (thus, optimal processability) than in Examples 1 and 2. According to the present invention, it is more preferred to have a higher temperature of fusion in combination with a relatively high Ml. Even slight increases in the intrinsic melting and softening temperature, respectively, have an enormously diminished effect on effective sterilization times, and thus on operating cycle times, in continuous production. All exemplary materials according to the present invention that have a DSC melting temperature of between 119 and 120°C have a corresponding Vicat A or softening temperature of between 110-10 and 111°C. The time-consuming sterilization procedure for blow/fill/seal PE packages is in fact the rate-limiting step in production. As for the change in the melting temperature of the material alone, a change from 110 (prior techniques) to at least 115 °C of effective sterilization temperature, as feasible with the material of the present invention, translates into a huge reduction of 150 minutes for 49 min in the sterilization time as exemplified in Figure 4 (surviving condition, ie no individual viable organism surviving - SAL = 0%).
    权利要求:
    Claims (17)
    [0001]
    1. Low density polyethylene (LDPE), characterized in that it is obtained by radical polymerization of ethylene, in which LDPE is a homopolymer that has a density of at least 0.932 g/cm3 or more, has a Mw of 60,000 to 130,000 g/mol, has a molecular weight distribution Mw/Mn from 3 to 15, and has a melt index (MI) (190°C/2.16 kg) greater than 0.45 g/10 min to 1.25 g/10 min.
    [0002]
    2. LDPE according to claim 1, characterized in that, during the radical polymerization, a chain transfer agent is used which is an aldehyde from C3 to C10, preferably the chain transfer agent used is propanal.
    [0003]
    3. LDPE according to claim 1, characterized in that the density of LDPE is from 0.932 to 0.936 g/cm3, preferably from 0.933 to 0.935 g/cm3.
    [0004]
    4. LDPE according to claim 1, characterized in that LDPE has a melting temperature > 118°C at DSC, measured in accordance with ISO 11357-3 (1999).
    [0005]
    5. LDPE according to claim 1, characterized in that the LDPE has a modulus E of at least 470 MPa, preferably at least 500 MPa.
    [0006]
    6. LDPE according to claim 1, characterized in that LDPE has a Mw of 80,000 to 120,000 g/mol.
    [0007]
    7. LDPE according to claim 1 or 4, characterized in that the LDPE has a temperature of the 2nd heat of fusion peak (Tm2) in a temperature range between 118°C and 122°C.
    [0008]
    8. LDPE according to any one of claims 1 to 7, characterized in that LDPE is a homopolymer that has been radically polymerized in the presence of t-butyl ester of branched alkanoic peracids from C4 to C15, in the presence of of propanal and in the absence of an effective amount of oxygen to make oxygen an initiator.
    [0009]
    LDPE according to claim 1, characterized in that it has a molecular weight distribution Mw/Mn of from 3 to 10.
    [0010]
    10. Process for manufacturing LDPE as defined in any one of claims 1 to 9, characterized in that it comprises the steps of conducting polymerization of ethylene under high pressure i.) adding to a tubular reactor that has at least two zones of consecutive reaction times, as defined by the number of inputs of the available reactants, in preference to a tubular reactor having only three reaction zones, at the first inlet to the first reactor zone, a mixture of peroxides comprising at least one first peroxide that has a half decay time < 0.1 h at 105°C in chlorobenzene and further comprising at least one second peroxide which has a half decay time > 0.1 h at 105°C in chlorobenzene, ii.) by adding to said reactor at the second inlet, and at any other available inlet, a peroxide mixture consisting essentially of at least one second peroxide which has a half decay time > 0.1 h at 105°C in chlorobenzene, which may be the same or different from the second peroxide used in step i.), iii.) collecting the polyethylene product from the reactor, and preferably with the proviso that said first and second initiators used have a temperature half-life in 1 min from 80°C to 160°C.
    [0011]
    11. Process according to claim 10, characterized in that the second peroxide in step i.) represents 50% or less of the total amount of peroxide added in the first entry.
    [0012]
    12. Process according to claim 10, characterized in that said third and/or second peroxides are tertiary or secondary alkyl esters from C3 to C10 of branched or unbranched alkanoic peracids from C4 to C15, which acids may carry halogen selected from the group of F, Cl in the alkyl group, preferably t-butyl ester of C4 to C15 branched alkanoic peracids.
    [0013]
    13. Process according to claim 10, characterized in that the maximum reactor temperature is controlled in each reactor zone at < 230°C, and more preferably the reactor pressure is > 260 MPa (> 2600 bar), more preferably the reactor pressure is 270 to 320 MPa (2700 and 3200 bar), and most preferably the reactor pressure is 290 to 310 MPa (2900 and 3100 bar).
    [0014]
    14. Process according to claim 10, characterized in that during the radical polymerization, a chain transfer agent is also used, which is selected from the group consisting of aldehyde, ketone or alkane branched from C3 to C10.
    [0015]
    15. Use of LDPE as defined in claim 1, characterized in that it is for the manufacture of a molded article, preferably by blow molding of the blow/fill/seal type.
    [0016]
    16. Molded article as defined in claim 15, characterized in that it is a bottle, can or ampoule manufactured by a blow molding/filling/sealing (BFS) type blow molding process, preferably a bottle, can or ampoule sealed with a volume of 0.001 L to 10 L.
    [0017]
    17. A molded article according to claim 16, characterized in that it comprises a sterile liquid for medical use, preferably for intravenous application to humans.
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    MX342547B|2016-10-03|
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    RU2564023C2|2015-09-27|
    CN102666609B|2016-06-01|
    US20120220738A1|2012-08-30|
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    AT542839T|2012-02-15|
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    WO2011057764A1|2011-05-19|
    KR20120091199A|2012-08-17|
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    法律状态:
    2020-12-22| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2021-01-19| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-05-25| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-07-06| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 10/11/2010, OBSERVADAS AS CONDICOES LEGAIS. PATENTE CONCEDIDA CONFORME ADI 5.529/DF, QUE DETERMINA A ALTERACAO DO PRAZO DE CONCESSAO. |
    优先权:
    申请号 | 申请日 | 专利标题
    EP09014063|2009-11-10|
    EP09014063.3|2009-11-10|
    PCT/EP2010/006829|WO2011057764A1|2009-11-10|2010-11-10|High pressure ldpe for medical applications|
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