Ethylene-based polymer and process for producing the same

Abstract

The present disclosure provides a composition. In an embodiment, a composition is provided and includes an ethylene homopolymer. The ethylene homopolymer has (i) a density from 0.9285 g / cc to 0.9315 g / cc, (ii) a melt index from 0.32 g / 10 min to 0.48 g / 10 min, and (iii) a hexane extractables content from 0.2 wt% to 0.7 wt%. The present disclosure also provides an article formed from the composition.

Description

ETHYLENE-BASED POLYMER AND PROCESS FOR PRODUCING THE SAMEBACKGROUND

[0001] The Blow Fill Seal (BFS) process is an aseptic processing technology used in medical packaging applications, such as filling and packaging of sterile pharmaceutical formulations. Known in the art is the use of low density polyethylene (LDPE) for the BFS process, due to its low levels of extractables and leachables. High level of extractables and leachables would be detrimental to medical applications, which require materials with high purity levels. However, LDPE cannot be sterilized at the higher temperatures that are needed for some BFS applications.

[0002] Thus, the art recognizes the on-going need for LDPE with lower hexane extractables for high purity medical applications and which can be sterilized at high temperatures. Specifically, a need exists for LDPE with low hexane extractables suitable for medical applications, and for use in a BFS process in particular.SUMMARY

[0003] The present disclosure provides a composition. In an embodiment, a composition is provided and includes an ethylene homopolymer. The ethylene homopolymer has (i) a density from 0.9285 g / cc to 0.9315 g / cc, (ii) a melt index from 0.32 g / 10 min to 0.48 g / 10 min, and (iii) a hexane extractables content from 0.2 wt% to 0.7 wt%. The present disclosure also provides an article formed from the composition.

[0004] The present disclosure provides an article. In an embodiment, an article is provided, and the article includes an ethylene homopolymer. The ethylene homopolymer has (i) a density from 0.9285 g / cc to 0.9315 g / cc, (ii) a melt index from 0.32 g / 10 min to 0.48 g / 10 min, and (iii) a hexane extractables content from 0.2 wt% to 0.7 wt%.DEFINITIONS

[0005] Any reference to the PeriodicTable of Elements is that as published by CRC Press, Inc., 1990- 1991. Reference to a group of elements in this table is by the new notation for numbering groups.

[0006] For purposes of United States patent practice, the contents of any referenced patent, patent application or publication are incorporated by reference in their entirety (or its equivalent U.S.version is so incorporated by reference) especially with respect to the disclosure of definitions (to the extent not inconsistent with any definitions specifically provided in this disclosure).

[0007] The numerical ranges disclosed herein include all values from, and including, the lower and upper value. For ranges containing explicit values (e.g., from 1 or 2, or 3 to 5, or 6, or 7), any subrange between any two explicit values is included (e.g., the range 1-7 above includes subranges of from 1 to 2; from 2 to 6; from 5 to 7; from 3 to 7; from 5 to 6; etc.).

[0008] Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percents are based on weight and all test methods are current as of the filing date of this disclosure.

[0009] The terms "blend" or "polymer blend," as used herein, refers to a mixture of two or more polymers. A blend may or may not be miscible (not phase separated at molecular level). A blend may or may not be phase separated. A blend may or may not contain one or more domain configurations, as determined from transmission electron spectroscopy, light scattering, x-ray scattering, and other methods known in the art. The blend may be affected by physically mixing two or more polymers on the macro level (for example, melt blending resins or compounding), or the micro level (for example, simultaneous forming within the same reactor).

[0010] The term "composition" refers to a mixture of materials which comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0011] The terms "comprising," "including," "having" and their derivatives, are not intended to exclude the presence of any additional component, step, or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term "comprising" may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term "consisting essentially of" excludes from the scope of any succeeding recitation any other component, step, or procedure, excepting those that are not essential to operability. The term "consisting of" excludes any component, step, or procedure not specifically delineated or listed. The term "or", unless stated otherwise, refers to the listed members individually as well as in any combination.

[0012] An "ethylene-based polymer" is a polymer that contains more than 50 mol percent (mol%) polymerized ethylene monomer (based on the total amount of polymerizable monomers) and, optionally, may contain at least one comonomer. Ethylene-based polymer includes ethylenehomopolymer, and ethylene copolymer (meaning units derived from ethylene and one or more comonomers). The terms "ethylene-based polymer" and "polyethylene" may be used interchangeably.

[0013] The term "ethylene monomer," or "ethylene," as used herein, refers to a chemical unit having two carbon atoms connected with a double bond, and each carbon bonded to two hydrogen atoms, wherein the chemical unit polymerizes with other such chemical units.

[0014] The term "linear low density polyethylene," (or "LLDPE") as used herein, refers to a linear ethylene / a-olefin copolymer containing heterogeneous short-chain branching distribution comprising units derived from ethylene and units derived from at least one C3-C10 a-olefin, or C4-C8 a-olefin comonomer. LLDPE is characterized by little, if any, long chain branching, in contrast to conventional LDPE. LLDPE has a density from 0.910 g / cc to less than 0.940 g / cc.

[0015] The term "low-density polyethylene" or "LDPE," also referred to as "high pressure ethylene polymer" is an ethylene-based polymer that is highly long chain branched and can be entirely homopolymerized (ethylene homopolymer) or copolymerized (ethylene copolymer). LDPE resins typically have a density in the range of 0.915 to 0.935 g / cm3. LDPE is distinct from LLDPE.

[0016] An "olefin" is an unsaturated, aliphatic hydrocarbon having a carbon-carbon double bond.

[0017] The term "polymer" or a "polymeric material," as used herein, refers to a compound prepared by polymerizing monomers, whether of the same or a different type, that in polymerized form provide the multiple and / or repeating "units" or "mer units" that make up a polymer. The generic term "polymer" thus embraces the term homopolymer, usually employed to refer to polymers prepared from only one type of monomer, and the term copolymer, usually employed to refer to polymers prepared from at least two types of monomers. It also embraces all forms of copolymer, e.g., random, block, etc. The terms "ethylene / a-olefin polymer" and "propylene / a-olefin polymer" are indicative of copolymer as described above prepared from polymerizing ethylene or propylene respectively and one or more additional, polymerizable a-olefin monomers. It is noted that although a polymer is often referred to as being "made of" one or more specified monomers, "based on" a specified monomer or monomer type, "containing" a specified monomer content, or the like, in this context the term "monomer" is understood to be referring to the polymerizedremnant of the specified monomer and not to the unpolymerized species. In general, polymers herein are referred to as being based on "units" that are the polymerized form of a corresponding monomer.TEST METHODS

[0018] Density. Samples for density measurements were prepared according to ASTM D 4703- 10. Samples were pressed at 374°F (190°C), for five minutes, at 10,000 psi (68 MPa). The temperature was maintained at 374°F (190°C) for the above five minutes, and then the pressure was increased to 30,000 psi (207 MPa) for three minutes. This was followed by a one minute hold at 70^F (21^C) and 30,000 psi (207 MPa). Measurements were made within one hour of sample pressing using ASTM D792-08, Method B.

[0019] Melt index (Ml or 12), was measured in accordance with ASTM D 1238-10, Condition 190°C / 2.16 kg, Method B, and was reported in grams eluted per 10 minutes.

[0020] Triple Detector Gel Permeation Chromatography (TD-GPC). The chromatographic system consisted of a PolymerChar GPC-IR (Valencia, Spain) high temperature GPC chromatograph equipped with an internal IR5 infra-red detector (IR5) and 4-capillary viscometer (DV) coupled to a Precision Detectors (Now Agilent Technologies) 2-angle laser light scattering (LS) detector Model 2040. For all absolute Light scattering measurements, the 15-degree angle is used for measurement. The autosampler oven compartment was set at 160^ Celsius and the column compartment was set at 150° Celsius. The columns used were 4 Agilent "Mixed A" 30cm 20- micron linear mixed-bed columns. The chromatographic solvent used was 1,2,4 trichlorobenzene (TCB) and contained 200 ppm of butylated hydroxytoluene (BHT). The solvent source was nitrogen sparged. The injection volume used was 200 microliters and the flow rate was 1.0 milliliters / minute.

[0021] Calibration of the GPC column set was performed with 21 narrow molecular weight distribution polystyrene standards with molecular weights ranging from 580 to 8,400,000 and were arranged in 6 "cocktail" mixtures with at least a decade of separation between individual molecular weights. The standards were purchased from Agilent Technologies. The polystyrene standards were prepared at 0.025 grams in 50 milliliters of solvent for molecular weights equal to or greater than 1,000,000, and 0.05 grams in 50 milliliters of solvent for molecular weights lessthan 1,000,000. The polystyrene standards were dissolved at 80 degrees Celsius with gentle agitation for 30 minutes then cooled and the room temperature solution is transferred cooled into the autosampler dissolution oven at 160^C for 30 minutes. The polystyrene standard peak molecular weights were converted to polyethylene molecular weights using Equation 1 (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)):where M is the molecular weight, A has a value of 0.4074 and B is equal to 1.0.

[0022] A fifth order polynomial was used to fit the respective polyethylene-equivalent calibration points.

[0023] The total plate count of the GPC column set was performed with decane which was introduced into blank sample via a micropump controlled with the PolymerChar GPC-IR system. The plate count for the chromatographic system should be greater than 18,000 for the 4 Agilent "Mixed A" 30cm 20-micron linear mixed-bed columns.

[0024] Samples were prepared in a semi-automatic manner with the PolymerChar "Instrument Control" Software, wherein the samples were weight-targeted at 2 mg / ml, and the solvent (contained 200ppm BHT) was added to a pre nitrogen-sparged septa-capped vial, via the PolymerChar high temperature autosampler. The samples were dissolved for 3 hours at 160° Celsius under "low speed" shaking.

[0025] The calculations of Mn(CC), Mw(CC), and Mz(CC) were based on GPC results using the internal IR5 detector (measurement channel) of the PolymerChar GPC-IR chromatograph according to Equations 2-4, using PolymerChar GPCOne™ software, the baseline-subtracted IR chromatogram at each equally-spaced data collection point (i), and the polyethylene equivalent molecular weight obtained from the narrow standard calibration curve for the point (i) from Equation 1.

[0026] In orderto monitor the deviations overtime, a flowrate marker (decane) was introduced into each sample via a micropump controlled with the PolymerChar GPC-IR system. This flowrate marker (FM) was used to linearly correct the pump flowrate (Flowrate(nominal)) for each sample by RV alignment of the respective decane peak within the sample (RV(FM Sample)) to that of the decane peak within the narrow standards calibration (RV(FM Calibrated)). Any changes in the time of the decane marker peak are then assumed to be related to a linear-shift in flowrate (Flowrate(effective)) for the entire run. After calibrating the system based on a flow marker peak, the effective flowrate (with respect to the narrow standards calibration) is calculated as Equation 5. Processing of the flow marker peak was done via the PolymerChar GPCOne™ Software. Acceptable flowrate correction is such that the effective flowrate should be within + / -0.5% of the nominal flowrate.Flowrate(effective) = Flowrate(nominal) * (RV(FM Calibrated) / RV(FM Sample)) (EQS)

[0027] For the determination of the viscometer and light scattering detector offsets from the IR5 detector, the systematic Approach for the determination of multi-detector offsets is done in a manner consistent with that published by Balke, Mourey, et. Al. (Mourey and Balke, Chromatography Polym. Chpt 12, (1992)) (Balke, Thitiratsakul, Lew, Cheung, Mourey, Chromatography Polym. Chpt 13, (1992)), optimizing triple detector log (MW and IV) results from a linear homopolymer polyethylene standard (3.5 > Mw / Mn > 2.2) with a molecular weight in the range of 115,000 to 125,000 g / mol to the narrow standard column calibration results from the narrow standards calibration curve using PolymerChar GPCOne™ Software.

[0028] The absolute molecular weight data was obtained in a manner consistent with that published by Zimm (Zimm, B.H., J. Chem. Phys., 16, 1099 (1948)) and Kratochvil (Kratochvil, P., Classical Light Scattering from Polymer Solutions, Elsevier, Oxford, NY (1987)) using PolymerChar GPCOne™ software. The overall injected concentration, used in the determination of the molecular weight, was obtained from the mass detector area and the mass detector constant, derived from a suitable linear polyethylene homopolymer, or one of the polyethylene standards of known weight-average molecular weight. The calculated molecular weights (using GPCOne™) were obtained using a light scattering constant, derived from one or more of the polyethylene standards mentioned below, and a refractive index concentration coefficient, dn / dc, of -0.104.Generally, the mass detector response (IR5) and the light scattering constant (determined using GPCOne™) should be determined from a linear standard with a molecular weight in excess of about 50,000 g / mole. The viscometer calibration (determined using GPCOne™) can be accomplished using the methods described by the manufacturer, or, alternatively, by using the published values of suitable linear standards, such as Standard Reference Materials (SRM) 1475a (available from National Institute of Standards and Technology (NIST)). A viscometer constant (obtained using GPCOne™) is calculated which relates specific viscosity area (DV) and injected mass for the calibration standard to its intrinsic viscosity. The chromatographic concentrations are assumed low enough to eliminate addressing 2ndviral coefficient effects (concentration effects on molecular weight).

[0029] The absolute weight average molecular weight (MW(Abs>) is obtained (using GPCOne™) from the Area of the Light Scattering (LS) integrated chromatogram (factored by the light scattering constant) divided by the mass recovered from the mass constant and the mass detector (IR5) area. The molecular weight and intrinsic viscosity responses are linearly extrapolated at chromatographic ends where signal to noise becomes low (using GPCOne™).Other respective moments, Mn<abs), Mw(abs), and Mz(abs) are be calculated according to Equations6-8 as follows:

[0030] gpcBR Branching Index by Triple Detector GPC (TD-GPC). The gpcBR branching index is determined by first calibrating the light scattering, viscosity, and infrared IR5 detectors as described previously. Baselines are then subtracted from the light scattering, viscometer, and IR5 (measurement channel) chromatograms. Integration windows are then set to ensure integration of all of the low molecular weight retention volume range in the light scattering and viscometer chromatograms that indicate the presence of detectable polymer from the infrared (IR5)chromatogram. Linear polyethylene standards are then used to establish polyethylene and polystyrene Mark-Houwink constants. Upon obtaining the constants, the two values are used to construct two linear reference conventional calibrations for polyethylene molecular weight and polyethylene intrinsic viscosity as a function of elution volume, as shown in Equations (9) and(10):

[0031] The gpcBR branching index is a robust method for the characterization of long chain branching as described in Yau, Wallace W., "Examples of Using 3D-GPC— TREE for Polyolefin Characterization," Macromol. Symp., 2007, 257, 29-45. The index avoids the "slice-by-slice" 3D- GPC calculations traditionally used in the determination of g' values and branching frequency calculations, in favor of whole polymer detector areas. From TD-GPC data, one can obtain the sample bulk absolute weight average molecular weight (MW(Abs>) by the light scattering (LS) detector, using the peak area method. The method avoids the "slice-by-slice" ratio of light scattering detector signal over the concentration detector signal, as required in a traditional g' determination.

[0032] With TD-GPC, sample intrinsic viscosities are also obtained independently using Equation(11). The area calculation in Equation (11) offers more precision, because, as an overall sample area, it is much less sensitive to variation caused by detector noise and TD-GPC settings on baseline and integration limits. More importantly, the peak area calculation is not affected by the detector volume offsets. Similarly, the high-precision sample intrinsic viscosity ([ / ?]) is obtained by the area method shown in Equation (11):where hspistands for the specific viscosity as acquired from the viscometer detector.

[0033] To determine the gpcBR branching index, the light scattering elution area for the sample polymer is used to determine the molecular weight of the sample (MW( bs)). The viscositydetector elution area for the sample polymer is used to determine the intrinsic viscosity ([ / ?]) of the sample.

[0034] Initially, the molecular weight and intrinsic viscosity for a linear polyethylene standard sample, such as SRM1475a or an equivalent, are determined using the conventional calibrations ("cc") for both molecular weight and intrinsic viscosity as a function of elution volume, per Equations (3) and (12):

[0035] Equation (13) is used to determine the gpcBR branching index: (Eq. 13)wherein [rj] is the measured intrinsic viscosity, [rj]ccis the intrinsic viscosity from the conventional calibration, MW(Abs) is the measured weight average molecular weight, and Mw(cc) is the weight average molecular weight of the conventional calibration. The weight average molecular weight by light scattering (LS) is commonly referred to as "absolute weight average molecular weight". The Mw(cc) from Equation (3) using conventional GPC molecular weight calibration curve ("conventional calibration") is often referred to as "polymer chain backbone molecular weight," "conventional weight average molecular weight".

[0036] All statistical values with the "cc" subscript are determined using their respective elution volumes, the corresponding conventional calibration as previously described, and the concentration (ci). The values of "MW(Abs)" and "[h]" are measured values based on the mass detector, LALLS, and viscometer areas. The value of KPE is adjusted iteratively, until the linear reference sample has a gpcBR measured value of zero. For example, the final values for a and Log K for the determination of gpcBR in this particular case are 0.725 and -3.391, respectively, for polyethylene, and 0.722 and -3.993, respectively, for polystyrene. These polyethylene coefficients were then entered into Equation 13.

[0037] Once the K and a values have been determined using the procedure discussed previously, the procedure is repeated using the branched samples. The branched samples are analyzed using the final Mark-Houwink constants obtained from the linear reference as the best "cc" calibration values are applied.

[0038] Differential Scanning Calorimetry (DSC). In preparation for Differential Scanning Calorimetry (DSC) testing, pellet samples are first loaded into a 1 in. diameter chase of 0.13mm thickness and compression molded into a film under 25,000 lbs of pressure at 190°C for approximately 10 seconds. The resulting film is then cooled to room temperature. The film is then subjected to a punch press in order to extract a disk that will fit the aluminum DSC test pan. The disk is then weighed individually (note: sample weight is approximately 5-6mg), placed into the aluminum pan, and sealed before being inserted into the DSC test chamber.

[0039] In reference to ASTM standard D3418, the DSC test is conducted using a heat-cool-heat cycle. First the sample is heated to 150°C with a rate of 10°C / min and held isothermally for 5 min. to remove thermal and process history. The sample is then quenched to -40°C at a rate of 10°C / min. and held isothermally once again for 5 min. Lastly, the sample is heated at a rate of 10°C / min. to 150°C for the second heating cycle. For data analysis, the melting temperatures and enthalpy of fusion is extracted from the second heating curve, whereas the enthalpy of crystallization is determined from the cooling curve. The enthalpy of fusion (Hf) and crystallization are obtained by integrating the DSC thermogram from -20°C to the end of melting and crystallization, respectively. The heat of fusion of 100% crystalline polyethylene is taken to be 292 J / g to calculate the wt% crystallinity using Equation A below. The DSC tests are performed using the TA Instruments Discovery DSC and data analyses are conducted via TA Instruments Universal Analysis and TRIOS software packages.

[0040] Equation A: % Crystallinity = ((Hf) / 292 J / g) x 100

[0041] n-Hexane Extractables. The term "n-hexane extractables" as used herein, refers to the amount of n-hexane soluble material extracted from the resultant polymer composition by n- hexane. The extraction process follows both the Food and Drug Administration (FDA) procedure for determining the solvent extractable portion of the polyolefin (21 CFR 177.1520 (d)(3)(ii)) and ASTM D5227. Polymer pellets are pressed or extruded into film with a thickness of 3 to 4 mils, then cut into l x l inch square pieces. Film pieces are weighed (2.5 ± 0.05g) then placed in a basket then extracted for two hours in a n-hexane vessel at 49.5 ± 0.5 °C in a heated water bath as described in ASTM D5227. After two hours, the films are removed, rinsed with clean n-hexane,and dried in a vacuum oven (80 ± 5°C) at full vacuum for two hours. The films are then placed in a desiccator and allowed to cool to room temperature for a minimum of one hour. The films are then reweighed, and the amount of mass loss due to extraction in n-hexane is calculated. N- hexane extractables are reported in wt%.

[0042] 1H NMR. Nuclear Magnetic Resonance H NMR for unsaturations). N MR spectroscopic methods for determining polyethylene unsaturation, for example see Busico, V., et al., Macromolecules, 2005, 38, 6988.

[0043] 1 / 7 NMR Sample Preparation. Samples were prepared by adding ~0.1 g of sample to 3.25g of 50 / 50 by weight l,l,2,2-tetrachlorethane-d2 / perchloroethylene (TCE / PCE) containing 0.001 M Cr(AcAc)s and about 75 ppm butylated hydroxytoluene (BHT), in a Norell 1001-7 10mm NMR tube. The samples were capped, sealed with Teflon tape, and then heated and vortexed at about 110 to 115°C to dissolve and ensure homogeneity.

[0044] 1H NMR Data Acquisition Parameters.1H NMR was performed on a Bruker AVANCE 600 MHz spectrometer equipped with a Bruker high-temperature CryoProbe at a sample temperature of 120°C. Spectra were acquired with ZG pulse, 1.8s AQ, 64 or 128 scans with a relaxation delay of 14s.

[0045] 1H NMR Data Analysis.3H NMR Calculations for unsaturated groups per one thousand carbon atoms (1000C). The spectra were referenced to the residual proton signal of TCE at 6.0 ppm. The total polymer integral from about -0.5 to 2.5 ppm was set to an arbitrary value, for example, 2000. The corresponding integrals for unsaturations (cis- and trans-vinylenes from about 5.40 to 5.60 ppm, trisubstituted from about 5.16 to 5.35 ppm, vinyl from about 5.0 to 5.15 ppm, and vinylidene from about 4.75 to 4.85 ppm) were obtained. The BHT -OH signal at about 4.9 ppm was not included in the integral areas. The integral of the whole polymer is divided by 2 to obtain the total polymer carbons. 1000 in this example. The unsaturated group integrals divided by the corresponding number of protons contributing to that integral represent the moles of each type of unsaturation per 1000 moles of total polymer carbons. This is referred to as unsaturated groups per 1000 carbons ("100 / C").

[0046] 13C Nuclear Magnetic Resonance (13C NMR for Branching). Samples for13C NMR were prepared by adding approximately 3g of 1,1,2,2-tetrachloroethane (TCE) containing 25 wt% TCE-d2 and 0.025 M Cr(AcAc)3, to about 0.25 g polymer sample, in a 10 mm NMR tube. The samples were then dissolved and homogenized by heating the tube and its contents to 120-140°C using a heating block and vortex mixer. Each dissolved sample was visually inspected to ensure homogeneity. Samples were thoroughly mixed immediately prior to analysis and were not allowed to cool before insertion into the heated NMR sample holders.

[0047] All data were collected using a Bruker 600 MHz spectrometer equipped with a 10 mm high temperature cryoprobe. The13C data was acquired using a 7.8 second pulse repetition delay, 90-degree flip angles, and inverse gated decoupling, with a sample temperature of 120°C. All measurements were made on non-spinning samples in locked mode. Samples were allowed to thermally equilibrate prior to data acquisition. The13C NMR chemical shifts were internally referenced to the EEE triad at 30.0 ppm. Table A lists the peak assignments used for branching measurement in LDPE. The "C6+" value is a direct measure of C6+branches in LDPE, where the long branches are not distinguished from "chain ends." The "32.2 ppm" peak, representing the third carbon from the end of all chains or branches of six or more carbons, is used to determine the "C6+" value.

[0048] Table A: Branching Type and13C NMR integral ranges used for quantitationCTA = chain transfer agent or telogen

[0049] Melt strength. Melt strength measurements were conducted on a Gbttfert Rheotens71.97 (Gbttfert Inc.; Rock Hill, SC), attached to a Gbttfert Rheotester 2000 capillary rheometer. The melted sample (about 25 to 30 grams) was fed with a Gbettfert Rheotester 2000capillary rheometer, equipped with a flat entrance angle (180 degrees) of length of 30 mm, diameter of 2.0 mm, and an aspect ratio (length / diameter) of 15. After equilibrating the samples at 190 °C for 10 minutes, the piston was run at a constant piston speed of 0.265 mm / second. The standard test temperature was 190°C. The sample was drawn uniaxia lly to a set of accelerating nips, located 100 mm below the die, with an acceleration of 2.4 mm / s2The tensile force was recorded as a function of the take-up speed of the nip rolls. Melt strength was reported as the average plateau force (cN) before the strand broke. The following conditions were used in the melt strength measurements: plunger speed = 0.265 mm / second; wheel acceleration = 2.4 mm / s2; capillary diameter = 2.0 mm; capillary length = 30 mm; and barrel diameter = 12 mm.

[0050] Viscosity. For preparation, test samples were initially placed into a 1.5 in. diameter chase of thickness 3.10mm and compression molded at a pressure of 25,000 lbs. for 6.5 min. at 190°C with a Carver Hydraulic Press (Model #4095.4NE2003). After cooling to room temperature, the sample is extracted to await rheological testing.

[0051] The DMS (dynamic mechanical spectroscopy) frequency sweep is conducted using 25mm parallel plates at frequencies ranging from 0.1 to 100 rad / s. The test gap separating the plates is 1.8mm and a strain that satisfies linear viscoelastic conditions is utilized, typically 10% strain. Each test is conducted under a nitrogen atmosphere and isothermal conditions at 190°C. To initiate the DMS test, the rheometer oven is first allowed to equilibrate at 190°C for at least 30 min before loading the sample into the test geometry. The sample is then equilibrated in the oven, with the door closed, for 1 min. The test gap is then set to 1.8 mm, and the sample is allotted 5 min. to relax the resulting normal force. Afterwards, the oven is quickly opened, and the sample is trimmed so that no polymer is outside the diameter of the plates. The DMS measurement is then initiated after reclosing the oven. During the test, the shear elastic or storage modulus (G'), the viscous modulus (G") and complex viscosity are measured. All DMS frequency tests are conducted on an ARES-G2 rotational rheometer manufactured by TA Instruments. Data analyses are conducted via TA Instruments TRIOS software.BRIEF DESCRIPTION OF THE DRAWINGS

[0052] FIG. 1 is a chart showing the chemical structures for different types of carbon-carbon double bonds (unsaturation in polymer chain) for vinylene, trisubstituted, vinyl, and vinylidene.

[0053] FIG. 2 is a block diagram of the process reaction system used to produce the inventive examples.

[0054] FIG. 3 is a perspective view of a blow-fill-seal ("BFS") ampoule in accordance with an embodiment of the present disclosure.DETAILED DESCRIPTION

[0055] The present disclosure provides a composition. In an embodiment, the composition includes an ethylene homopolymer having (i) a density from 0.9285 g / cc to 0.9315 g / cc; (ii) a melt index from 0.32 g / 10 min to 0.48 g / 10 min; and (iii) a hexane extractables content from 0.2 wt% to 0.7 wt%.1. Composition

[0056] The present ethylene homopolymer composition is produced under polymerization conditions in a polymerization reactor having an autoclave reactor portion and a tubular reactor portion (interchangeably referred to as "autoclave / tubular hybrid"). The autoclave reactor portion has two or more injection points for an initiator and ethylene monomer feeds. The tubular portion has two or more injection points for the initiator and ethylene monomer feed.

[0057] The term "polymerization conditions," as used herein, refers to process parameters under which ethylene is polymerized in the presence of a chain transfer agent. Polymerization conditions include, for example, polymerization reactor conditions (reactor type), reactor pressure, reactor temperature, concentrations of reagents and polymer, solvent, carrier, residence time and distribution, influencing the molecular weight distribution and polymer structure. The term polymerization conditions, as used herein, includes (i) the presence of a chain transfer agent that is propionaldehyde and (ii) the presence of a free radical initiator with the ethylene monomer in the polymerization reactor.

[0058] A "chain transfer agent," or CTA as used herein, refers to a compound that is capable ofexchanging an alkyl group or a polymeryl group on the chain transfer agent with a growing polymer chain on the catalyst, the exchange resulting in termination of the polymer chain growth under the polymerization conditions. The chain transfer agent can be an aldehyde (such as propionaldehyde, for example) and / or a ketone (such as methyl ethyl ketone, for example) and exclude other chain transfer agents such as alfa-olefins or alkanes such as propylene, isobutane, 1-butene and n-butane which lower the crystallinity of the resultant ethylene homopolymer.

[0059] A "free radical initiator," (or "initiator") as used herein, may include organic initiators such as dicumyl peroxide, di-tert-butyl peroxide, t-butyl perbenzoate, benzoyl peroxide, cumene hydroperoxide, t-butyl peroctoate, methyl ethyl ketone peroxide, 2,5dimethyl-2,5-di(t-butyl peroxy)hexane, lauryl peroxide, tert-butyl peracetate, and combinations thereof. Ethylene monomer is polymerized under the polymerization conditions (a polymerization reaction with propionaldehyde and one or more free radical initiators to form an ethylene homopolymer.

[0060] In an embodiment, the ethylene homopolymer is produced in an autoclave / tubular hybrid polymerization reactor under one, some, or all of the following polymerization conditions:(i) a first autoclave zone (top reactor zone) operating at a temperature from 150 °C to 170 °C, or from 160 °C to 170 °C, or from 165 °C to 170 °C; and / or(ii) a second autoclave zone (bottom reactor zone) operating at a temperature from 150 °C to 170 °C, or from 160 °C to 170 °C, or from 165 °C to 170 °C; and / or(iii) a reactor inlet having a pressure from 2350 bar to 2500 bar, or from 2400 bar to 2500 bar, or from 2400 bar to 2450 bar; and / or(iv) a first tubular zone operating at a temperature peak from 230 °C to 260 °C, or from 240 °C to 260 °C, or from 250 °C to 260 °C, and / or(vi) a second tubular zone operating at a temperature peak from 230 °C to 260 °C, or from 240 °C to 260 °C, or from 250 °C to 260 °C.

[0061] The ethylene homopolymer produced in the autoclave / tubular hybrid polymerization reactor under polymerization conditions is an LDPE. The ethylene homopolymer has one, some, or all of the following properties:(i) a density from 0.9250 g / cc to 0.9350 g / cc, or from 0.9290 g / cc to 0.9320 g / cc, orfrom 0.9285 g / cc to 0.9315 g / cc; and / or(ii) a melt index from 0.10 g / 10 min to 0.50 g / 10 min, or from 0.20 g / 10 min to 0.49 g / 10 min, or from 0.32 g / 10 min to 0.48 g / 10 min; and / or(iii) a hexane extractables content from 0.1 wt% to 0.8 wt%, or from 0.2 wt% to 0.7 wt%, or from 0.3 wt% to 0.6 wt%, or from 0.3 wt% to 0.5 wt%.

[0062] In an embodiment, the ethylene homopolymer produced in the autoclave / tubular hybrid under polymerization conditions is an LDPE. The ethylene homopolymer has one, some, or all of the following properties:(i) a density from 0.9250 g / cc to 0.9350 g / cc, or from 0.9290 g / cc to 0.9320 g / cc, or from 0.9285 g / cc to 0.9315 g / cc; and / or(ii) a melt index from 0.10 g / 10 min to 0.50 g / 10 min, or from 0.20 g / 10 min to 0.49 g / 10 min, or from 0.32 g / 10 min to 0.48 g / 10 min; and / or(iii) a hexane extractables content from 0.1 wt% to 0.8 wt%, or from 0.2 wt% to 0.7 wt%, or from 0.3 wt% to 0.6 wt%, or from 0.3 wt% to 0.5 wt%; and / or(iv) a crystallinity from 54% to 62%, or from 54% to 58%, or from 55% to 58%, or from 56% to 57%; and / or(v) an absolute weight average molecular weight (Mw(Abs)) from 150,000 to 220,000 g / mol, or from 170,000 to 210,000 g / mol, or from 190,000 to 210,000 g / mol; and / or(vi) an Mw(cc) / Mn(cc) from 4.5 to 6.5 or from 5.0 to 5.5; and / or(vii) a gpcBR from 1.2 to 2.0, or from 1.4 to 1.9, or from 1.5 to 1.8; and / or(viii) a vinylidene content from 0.050 / 1000 carbons to 0.080 / 1000 carbons, or from 0.060 / 1000 carbons to 0.070 / 1000 carbons; and / or(ix) a total unsaturation per 1000 carbons from 0.12 to 0.15, or from 0.12 to 0.14.2. Article

[0063] The present disclosure provides an article. In an embodiment, the article includes the present ethylene homopolymer. The ethylene homopolymer has (i) a density from 0.9285 g / ccto 0.9315 g / cc; (ii) a melt index from 0.32 g / 10 min to 0.48 g / 10 min; and (iii) a hexane extractables content from 0.2 wt% to 0.7 wt%.

[0064] In an embodiment, the article is a container. The container includes a sidewall. The sidewall is composed of the ethylene homopolymer.

[0065] In an embodiment, the container is a Blow-Fill-Seal container ("BFS" container). A "BFS container," as used herein, is a container produced in an automated manufacturing process by which polymeric containers, such as bottles or ampoules, are, in a continuous operation, blow- formed, filled, and sealed. The BFS container is manufactured in a sterile, enclosed area inside a machine. An advantage of the BFS manufacturing process is that the process is a closed and automated system. The BFS container is formed within the BFS machine, filled with sterile solution, and the BFS container is closed, with limited, or no, human intervention.

[0066] FIG. 3 shows a BFS container 110. In the BFS container manufacturing process, the present composition ( / .e., LDPE, and optional additives) is melted, extruded into a sidewall 112 which is shaped in the form of a cylindrical tube (a "parison," or a continuous sidewall), and formed into a container by blowing sterile air or nitrogen into the cylindrical tube to force the present composition (in the melted state) into the shape of the mold. Cooling of the container begins within seconds after it is formed, as the mold is chilled. A medicament 114 (typically a liquid, a semi-liquid or a gel) is then filled into the just-formed polymeric container while still inside the mold. The BFS machine then closes sidewall 112 upon itself by sealing the top end and the bottom end of the cylindrical tube, thereby forming a sealed BFS container 110 with sidewall 112 defining a body portion 116, a top portion 118, a bottom portion 120, and a closed chamber 122 with medicament 114 (or a cosmetic) therein. In other words, BFS container 110 is made from a single continuous sidewall 112. BFS container also includes a tab 124 (also made from the present composition) for opening container 110 and dispensing, or otherwise discharging, medicament 114 from chamber 122.

[0067] Sidewall 112 of container 110 is composed of the present ethylene homopolymer. The ethylene homopolymer has one, some, or all of the following properties:(i) a density from 0.9250 g / cc to 0.9350 g / cc, or from 0.9290 g / cc to 0.9320 g / cc, or from 0.9285 g / cc to 0.9315 g / cc; and / orYl(ii) a melt index from 0.10 g / 10 min to 0.50 g / 10 min, or from 0.20 g / 10 min to 0.49 g / 10 min, or from 0.32 g / 10 min to 0.48 g / 10 min; and / or(iii) a hexane extractables content from 0.1 wt% to 0.8 wt%, or from 0.2 wt% to 0.7 wt%, or from 0.3 wt% to 0.6 wt%, or from 0.3 wt% to 0.5 wt.

[0068] In an embodiment, sidewall 112 of container 110 is composed of the present ethylene homopolymer. The ethylene homopolymer has one, some, or all of the following properties:(i) a density from 0.9250 g / cc to 0.9350 g / cc, or from 0.9290 g / cc to 0.9320 g / cc, or from 0.9285 g / cc to 0.9315 g / cc; and / or(ii) a melt index from 0.10 g / 10 min to 0.50 g / 10 min, or from 0.20 g / 10 min to 0.49 g / 10 min, or from 0.32 g / 10 min to 0.48 g / 10 min; and / or(iii) a hexane extractables content from 0.1 wt% to 0.8 wt%, or from 0.2 wt% to 0.7 wt%, or from 0.3 wt% to 0.6 wt%, or from 0.3 wt% to 0.5 wt%; and / or(iv) a crystallinity from 54% to 62%, or from 54% to 62%, or from 54% to 58% or from 55% to 58%, or from 56% to 57%; and / or(v) an absolute weight average molecular weight (Mw(Abs)) from 150,000 to 220,000 g / mol, or from 170,000 to 210,000 g / mol, or from 190,000 to 210,000 g / mol; and / or(vi) an Mw(cc) / Mn(cc) from 4.5 to 6.5 or from 5.0 to 5.5; and / or(vii) a gpcBR from 1.2 to 2.0, or from 1.4 to 1.9 or from 1.5 to 1.8; and / or(viii) a vinylidene content from 0.050 / 1000 carbons to 0.080 / 1000 carbons, or from 0.060 / 1000 carbons to 0.070 / 1000 carbons; and / or(ix) a total unsaturation per 1000 carbons from 0.12 to 0.15, or from 0.12 to 0.14.

[0069] Nonlimiting examples of medicament present in chamber 122 and in direct contact with sidewall 112 include liquid ophthalmics (such as sterile eye drops), inhalational anesthetics, biologies, lavaging agents, and vaccines.

[0070] Sidewall 112 may be uniform thickness or may vary in thickness along a length of BFS container 110, from top portion 118, to body portion 116, and to bottom portion 120. In an embodiment, continuous sidewall 112 forms closed top portion 118, body portion 116, andbottom portion 120. In a further embodiment, continuous sidewall 112 has a thickness from 0.3 millimeters (mm) to 2.5 mm, or from 0.3 mm to 1.5 mm, or from 0.3 mm to 1.0 mm and forms a closed chamber having a volume from 0.1 cubic centimeters (cc) to 200 cc, or from 0.5 cc to 100 cc, or from 1.0 cc to 50 cc.

[0071] In an embodiment, sidewall 112 is a continuous sidewall with no seam, and / or with no seal, and / or with no heat seal.

[0072] In an embodiment, body portion 116 is a continuous body portion and has no seam, and / or body portion 116 has no heat seal.

[0073] By way of example, and not limitation, some embodiments of the present disclosure will now be described in detail in the following examples.EXAMPLES

[0074] Inventive ethylene homopolymer was produced via a high pressure, free-radical initiated polymerization process in an autoclave / tubular hybrid polymerization reactor, as depicted in FIG. 2. The autoclave / tubular hybrid polymerization reactor A includes autoclave reactor portion 12 (or "AC reactor") and tubular reactor portion 13 (or "two-zone reactor"). The autoclave reactor portion 12 has two or more injection points for the initiator and monomer feeds. The tubular reactor portion 13 has two peroxide injection points making it a two-zone tubular reactor 13 in series with the autoclave reactor 12.

[0075] The autoclave / tubular hybrid polymerization reactor A includes autoclave reactor portion 12 and tubular reactor portion 13. The autoclave / tubular hybrid polymerization reactor A is a component in a process reaction system 19. The process reaction system 19 in FIG. 2 is a partially closed-loop dual recycle high-pressure, low density polyethylene production system. The process reaction system 19 includes a fresh ethylene feed 1, a booster compressor 14, a primary compressor 15, a hyper compressor 16, and the autoclave / tubular hybrid polymerization reactor A includes autoclave reactor portion 12 and tubular reactor portion 13. The autoclave / tubular hybrid polymerization reactor includes autoclave reactor portion 12 and tubular reactor portion 13. The autoclave reactor portion 12 includes an autoclave reactor portion with three (or four) adiabatic autoclave reactor zones coupled to the tubular reactorportion with a two-zone tubular reactor 13. The autoclave reactor portion 12 contains 50 / 50 split ethylene feeds 11 and 3, with the first ethylene feed 11 being fed to the top of autoclave reactor portion 12 (i.e., autoclave zone 1), and the second ethylene feed 3 fed to the side of autoclave reactor portionl2 at autoclave zone 2. Peroxide initiators are injected into autoclave reactor portion to initiate the polymerization reactions. Peroxide initiators are also injected into tubular reactor portion 13. The tubular reactor portion 13 uses cooling jackets mounted around the outer shell of the tubular reactor. The polymer product (ethylene homopolymer) and the ethylene monomer were separated using a high-pressure separator 17, a high pressure recycle, a low pressure separator 18, and a low pressure recycle. The chain transfer agent (CTA) was then injected into the suction side of hyper compressor 16.

[0076] The polymerization conditions used for producing the inventive ethylene homopolymer and comparative samples are set forth in Tables 1A, IB, 1C, ID below. The numerals in parentheses in the "property" column in Table 1A and in Table 1C correspond to the reference numerals in FIG. 2.

[0077] Table 1A: Polymerization conditions for producing the inventive examples

[0078] The free radical initiator injected into the autoclave reactor portion is tert-butyl peroxypivalate. The free radical initiator for the tubular reactor portion is a mixture of tert-butylperoxy-2-ethylhexanoate and tert-butyl peroxyacetate. Table IB below provides the range of peroxide concentrations used.

[0079] Table IB. - peroxide concentrations

[0080] Table 1C: Process conditions for producing the inventive examplesCJ = cooling jacket

[0081] Applicant discovered using propionaldehyde ("PA") (Table 1C) as the sole CTA (i) contributes to narrowing the Mw / Mn of the ethylene homopolymer, (ii) has a carbonyl form, which forms a weak bond with hydrogen, which causes higher amounts of long chain branching (LCB), to increase the melt strength, and (iii) contributes to increasing the crystallinity, due to the high reactivity of propionaldehyde.

[0082] The cooling jackets ("CJ") in Table 1C are connected with different cooling drums, which are operated at different pressures. The pressures of the cooling drums can vary between 6-12 bar.

[0083] Table ID below provides polymerization conditions for comparative samples ("CS") CS 1- CS 5 where "tube" refers to a tubular polymerization reactor and "AC-LT" refers to an autoclave / tubular hybrid polymerization reactor as shown in FIG. 2.Table ID - Polymerization conditions

[0084] Inventive examples 1-3 (IE1-3) were produced using the polymerization conditions listed in Tables 1A, IB, and 1C. The properties of inventive examples ("IE") I El-3 and comparative samples 1-5 (CS1-5) are provided in Table 2 below.

[0085] Table 2: Properties of IE1-3 and CS1-5

[0086] The branching values of CS1-5 and IE2 are provided in Table 3 below.

[0087] Table 3: Branching values for CS1-5 and IE2 (in branches per 1000 carbons) as measured by13C NMR.Table 3

[0088] The unsaturation values for CS1-5 and IE2 are provided in Table 4 below.

[0089] Table 4: Unsaturation values of CS1-5 and IE2 (in unsaturation groups per 1000 carbons) as measured byTH NMR.

[0090] Table 5: The molecular weight values for I El-3 and CS1-5

[0091] Table 6: The gpcBR values for I El-3 and CS1-5

[0092] Table 7: The viscosity values of IE3 and CS1-5 measured by DMS at 190 °C

[0093] Bounded by no particular theory, Applicant discovered that the polymerization reaction of ethylene monomer in the autoclave / tubular hybrid polymerization reactor under polymerization conditions of Tables 1A, IB, 1C and including:(i) autoclave zone 1 temperature of 168°C,(ii) autoclave zone 2 temperature of 166.8°C,(iii) tubular zone 1 peak temperature of 257°C,(iv) tubular zone 2 peak temperature of 256°C,(v) reactor pressure of 2440 barg, and(vi) propionaldehyde feed rate of 16.7kg / hr unexpectedly yields ethylene homopolymer with density of 0.9285-0.9315 g / cc, high purity (less than 0.8 wt% hexane extractables) with high crystallinity (crystallinity greater than 50%) and low Ml (Ml less than 0.5 g / 10 min), which is desirable for blow-fill-seal applications and blow-fill-seal medical applications in particular.

[0094] I El-3 each has a lower hexane extractables content (i.e., higher purity) compared to the hexane extractables content of CS1-5 (I El-3 -- 0.38-0.41% compared to CS1-5 — 0.63-2.02%) and I El-3 exhibit high crystallinity (56.2-56.8%) and low Ml (0.40-0.43 g / 10 min) which is desired for medical blow-fill-seal applications.

[0095] It is specifically intended that the present disclosure not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.

Claims

CLAIMS1. A composition comprising: an ethylene homopolymer comprising(i) a density from 0.9285 g / cc to 0.9315 g / cc;(ii) a melt index from 0.32 g / 10 min to 0.48 g / 10 min; and(iii) a hexane extractables content from 0.2 wt% to 0.7 wt%.

2. The composition of claim 1 wherein the ethylene homopolymer has(iv) a crystallinity from 54% to 58%.

3. The composition of any of claims 1-2, wherein the ethylene homopolymer has(v) an absolute weight average molecular weight (Mw(Abs)) from 150,000 g / mol to 220,000 g / mol.

4. The composition of any of claims 1-3, wherein the ethylene homopolymer has(vi) a Mw(cc) / Mn(cc) from 4.5 to 6.5.

5. An article comprising: an ethylene homopolymer comprising(i) a density from 0.9285g / cc to 0.9315g / cc;(ii) a melt index from 0.32g / 10 min to 0.48g / 10 min; and(iii) a hexane extractables content from 0.2 wt% to 0.7 wt%.

6. The article of claim 5 wherein the ethylene homopolymer has(iv) a crystallinity from 54% to 58%.

7. The article of any of claims 5-6, wherein the ethylene homopolymer has(v) an absolute weight average molecular weight (Mw(Abs)) from 150,000 g / mol to 220,000 g / mol.

8. The article of any of claims 5-7, wherein the ethylene homopolymer has a Mw(cc) / Mn(cc) from 4.5 to 6.5.

9. The article of any of claims 5-8, wherein the article is a container comprising a sidewall, the sidewall comprising the ethylene homopolymer.

10. The article of claim 9 wherein the sidewall defines a closed chamber; and a medicament is present in the closed chamber.

11. The article of any of claims 9-10 wherein the sidewall is a monolayer structure and has a thickness from 0.3 mm to 2.5 mm.

12. The article of any of claims 9-11 wherein the closed chamber has a volume from 0.1 cc to 200 cc.

13. The article of any of claims 9-12 wherein the container is a blow-fill-seal container.

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