Patent Application
20150232589
The present invention is directed to metallocene-catalyzed ethylene-based polymers, blends of such ethylene-based polymers, and articles made therefrom. Methods of making articles, particularly films, are also described.
Both low density polyethylenes (LDPEs) made using a conventional high-pressure is process and linear low density polyethylenes (LLDPEs) produced using a Ziegler-Natta catalyst in a gas phase process, and blends and articles made therefrom, are generally known in the art. While such polyethylenes are sometimes preferred because they provide relatively low-cost solutions to a number of needs, their properties render them less desirable than other polyethylenes for a number of applications. For example, LLDPE and LDPE films cannot be produced in high-stalk bubble blown film lines due to a lack of melt strength, and therefore cannot be produced with balanced machine direction (MD)—transverse direction (TD) shrink properties.
To meet higher TD shrinkability requirements, a double-bubble extrusion process may be used, but that process requires that the LLDPE either be cross-linked or coextruded with polypropylene. Those films provide good optical properties and high TD shrinkability, but very low MD and TD tear resistance.
High density, high crystallinity and high melt strength polyethylene materials like conventional high density polyethylene (HDPE) are well suited for a high-stalk bubble blown film extrusion process. Through the high-stalk process, HDPE film is able to achieve high TD orientation which will cause high TD shrinkability. However, HDPE film will also exhibit low toughness, i.e., low dart, puncture and tear resistance, and poor optical properties, i.e., high haze, low gloss and low clarity.
There is a need for a polymer and a process which are able to produce polyethylene film with high TD shrinkability even at thin gauge, good toughness (particularly as measured by, e.g., MD tear, dart and puncture resistance) and good optical properties (e.g., low haze and high gloss). Certain metallocene-catalyzed polyethylenes are able to be used in blends for a high-stalk process because of the melt strength they exhibit, and are also able to contribute desired toughness and optical properties to the films that are produced therewith. There is also a need for a high melt strength polymer useful for making heavy gauge films (e.g., >10 mil thick) and which yields improved toughness properties, i.e., impact and tear strength and stress crack resistance. There is a further need for a high melt strength polymer suitable for blow molding and thermoforming applications resulting in stiff finished products with high gloss levels and stress cracking resistance.
Embodiments of the invention provide ethylene-based polymers comprising about 80.0 to 99.0 wt. % of polymer units derived from ethylene and about 1.0 to about 20.0 wt. % of polymer units derived from one or more C3 to C20 α-olefin comonomers. The ethylene-based polymer has a local maximum loss angle at a complex modulus, G*, of 2.50×104 to is 1.00×106 Pa, preferably 2.50×104 to 1.00×105 Pa and a local minimum loss angle at a complex modulus, G*, of 1.00×104 to 3.00×104 Pa, preferably 1.25×104 to 2.00×104 Pa.
In another aspect, embodiments of the invention provide ethylene-based polymers having a particular combination of composition and complex modulus G* at a loss angle, δ, of 60° (denoted G*60). The ethylene-based polymers comprise about 80.0 to 99.0 wt. % of polymer units derived from ethylene and about 1.0 to about 20.0 wt. % of polymer units derived from one or more C3 to C20 α-olefin comonomers. The complex modulus, G*60, is <2.50×103 Pa, preferably <2.00×103 Pa.
Particular embodiments of the ethylene-based polymers of the invention comprise about 80.0 to 99.0 wt. % of polymer units derived from ethylene and about 1.0 to about 20.0 wt. % of polymer units derived from one or more C3 to C20 α-olefin comonomers and have a Comonomer Branch Distribution Index (CDBI)≧70.0%, preferably ≧80.0%, preferably ≧85.0%, preferably ≧90.0%; a melt index, I2.16, of about 0.05 to about 0.50 g/10 min.; a density of from about 0.930 to about 0.950 g/cm3; and a MWD of about 2.5 to about 5.5, preferably 4.0 to 5.0. Preferably, the ethylene-based polymers have about 0.05 to 0.5 long-chain branches per/1000 C atoms.
The ethylene-based polymer may be blended with one or more other polymer components. Embodiments of the invention include blend compositions comprising: 0.1 to 99.9 wt. %, of an ethylene-based polymer, and 0.1 to 99.9 wt. % of a polymer selected from the group consisting of:high density polyethylene, linear low density polyethylene, low density polyethylene, medium density polyethylene, differentiated polyethylene, polypropylenes (e.g., impact copolymers as well as polypropylene homopolymers and random copolymers) and combinations thereof
The ethylene-based compositions and blends thereof described herein may be used to make various articles of manufacture. Articles may be made by any suitable method (e.g., injection molding, blow molding, extrusion coating, foaming, casting, and combinations thereof) Some such articles may be extruded monolayer or multilayer films. The ethylene-based polymers and blends thereof are particularly suitable for use in thermoformed extruded sheets, particularly multilayer thermoformed extruded sheets, wherein the cap layer of the sheet comprises the ethylene-based polymer or blend thereof Ethylene-based polymers described herein may also be particularly useful in pipe applications. In other embodiments, the article may be a multilayer film having a core layer comprising an ethylene-based polymer or blend thereof Such films typically include outer layers A and B in surface contact with opposing surfaces of the core layer. Some such films have beneficial shrink and tear properties (e.g., a TD shrink of 20.0 to 70.0% or a combination of beneficial shrink and tear properties e.g., a TD shrink of 20.0 to 70.0% and a MD Elmendorf Tear of 0.5 to 10 g/μm).
Embodiments of the invention provide a polymer composition having an unexpected combination of properties, particularly when formed into articles such as films. The compositions have surprising rheological properties indicative of unusual polymer chain structure. Some polymers have high melt strength, making them particularly suitable for high-stalk blown film processes. In coextruded films such polymer compositions can provide a core layer that imparts an unexpected balance of shrinkage in the transverse direction (TD) and a tear strength in the machine direction (MD). In articles such as thermoformed sheets, the polymer compositions provide a surface layer having unexpected combination of gloss and scratch resistance, particularly in articles for coextruded sheet applications.
In the following description, all numbers disclosed herein are approximate values, regardless whether the word “about” or “approximate” is used in connection therewith. They may vary by 1%, 2%, 5%, and sometimes, 10 to 20%. Whenever a numerical range with a lower limit, RL and an upper limit, RU, is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=RL+k*(RU−RL), wherein k is a variable ranging from 1% to 100% with a 1% increment, i.e., k is 1%, 2%, 3%, 4%, 5%, . . . , 50%, 51%, 52%, . . . , 95%, 96%, 97%, 98%, 99%, or 100%. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed.
The ethylene-based polymer compositions herein refer to a polyethylene copolymer having about 99.0 to about 80.0 wt. %, 99.0 to 85.0 wt. %, 99.0 to 87.5 wt. %, 99.0 to 90.0 wt. %, 99.0 to 92.5 wt. %, 99.0 to 95.0 wt. %, or 99.0 to 97.0 wt. %, of polymer units is derived from ethylene and about 1.0 to about 20.0 wt. %, 1.0 to 15.0 wt. %, 1.0 to 12.5 wt. %, 1.0 to 10.0 wt. %, 1.0 to 7.5 wt. %, 1.0 to 5.0 wt. %, or 1.0 to 3.0 wt. % of polymer units derived from one or more C3 to C20 α-olefin comonomers, preferably C3 to C10 α-olefins, and more preferably C4 to C8 α-olefins. The α-olefin comonomer may be linear or branched, and two or more comonomers may be used, if desired. Examples of suitable comonomers include propylene, butene, 1-pentene; 1-pentene with one or more methyl, ethyl, or propyl substituents; 1-hexene; 1-hexene with one or more methyl, ethyl, or propyl substituents; 1-heptene; 1-heptene with one or more methyl, ethyl, or propyl substituents; 1-octene; 1-octene with one or more methyl, ethyl, or propyl substituents; 1-nonene; 1-nonene with one or more methyl, ethyl, or propyl substituents; ethyl, methyl, or dimethyl-substituted 1-decene; 1-dodecene; and styrene. Particularly suitable comonomers include 1-butene, 1-hexene, and 1-octene, 1-hexene being most preferred.
Typically, although not necessarily, the ethylene-based polymers have a complex modulus, G*60, <2.50×103 Pa, preferably <2.00×103 Pa. The complex modulus can be measured at other loss angles. Some particular ethylene-based polymers have complex modulus at a loss angle, δ, of 50°, G*50, <50.00×103 Pa, preferably <25.00×103 Pa, preferably <20.00×103 Pa, preferably <10.00×103 Pa, preferably <5.00×103 Pa. Some ethylene based polymers have a G*=2,000 at a loss angle, δ, of ≦62.5°, particularly ≦60.0°, or from 60.0° to 62.5°, i.e., G*≦62.5=2.00×103, G*≦60.0 =2.00×103, or G*60.0-62.5=2.00×103.
Complex modulus and loss angles, δ, may be obtained from rheological data determined at the test temperature of 190 ° C. and analyzed using the Van Gurp-Palmen treatment (reference: M. Van Gurp and J. Palmen, Rheology Bulletin, 67, 5, 1998), whereby the loss angle, δ, (wherein δ=arctan−1(G″/G′); G″ represents the loss modulus (Pa) and G′ represents the storage modulus (Pa)) is plotted against the absolute value of the complex modulus |G*|=(G′2+G″2)″2. This representation of linear viscoelastic data is a powerful means of characterizing molecular and structural features of polymers. For example, low levels of long-chain branching in polyolefins can be detected and quantified on a relative basis, using this methodology.
Dynamic shear melt rheological data was measured with an Advanced Rheometrics Expansion System (ARES) using parallel plates (diameter=25 mm) at 190° C. using a pristine compression molded sample at each temperature. The measurements were made over the angular frequency that ranged from 0.01-100 rad/s. Depending on the molecular weight and temperature, strains of 10% and 15% were used and linearity of the response was verified. A nitrogen stream was circulated through the sample oven to minimize chain extension or cross-linking during the experiments. All the samples were compression molded at 190° C. and no stabilizers were added. A sinusoidal shear strain is applied to the material. If the strain amplitude is sufficiently small, the material behaves linearly.
While some polymers may be characterized by a value of the complex modulus at a particular loss angle as described above, another way to describe some ethylene-based polymers of the invention relates to features of the complex modulus values, G*, when considered over the range of loss angles from 30 to 90°. Such ethylene-based polymers may have a local maximum loss angle at a G* value of 2.50×104 to 1.00×106 Pa, preferably 2.50×104 to 1.00×105 Pa and a local minimum loss angle at a complex modulus, G*, of 1.00×104 to 3.00×104 Pa, preferably 1.25×104 to 2.00×104 Pa. In some such ethylene-based polymers, the local maximum loss angle is from 40.0 to 50.0°, preferably 40.0 to 45.0°, more preferably 42.5 to 45.0°. While not critical, some ethylene-based polymers may have a local minimum loss angle of from 40.0 to 50.0°, preferably 40.0 to 45.0°, more preferably 40.0 to 42.5°.
Some polyethylenes also have a strain hardening ratio of 1.0 to 10.0 at 10 sec−1. The upper limit on the range of the strain hardening ratio maybe 9.0, 8.0, 7.0, 6.0, 5.0, 4.0, 3.0, or 2.0. The lower limit on the range of the strain hardening ratio may be 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, or 9.0. Any combination lower and upper limits should be considered to be disclosed by the above limits on the strain hardening ratio, e.g., 2.0 to 9.0, 3.0 to 7.0, 1.0 to 4.0, 3.0 to 4.0 etc. “Strain Hardening Ratio” is defined as the ratio of two extensional viscosities: the numerator measured using an extensional viscometer reporting the maximum viscosity (at break), and the denominator being an extensional viscosity calculated from small amplitude strain experimental data using the method of Baumgaertel and Winter. The extensional viscosities are measured using the same experimental conditions (i.e., temperature, stabilization, etc.) as described in U.S. Pat. No. 6,225,432, incorporated herein by reference in its entirety.
Typically, the ethylene-based polymers also have a Composition Distribution Breadth Index (CDBI) of at least 70%, preferably ≧80.0%, preferably ≧85.0%, preferably ≧90.0%. CDBI is generally the weight percent of the ethylene-based polymer having a comonomer content within ±25% of the median comonomer content. The CDBI of a copolymer is readily determined utilizing well known techniques for isolating individual is fractions of a sample of the copolymer. One such technique is Temperature Rising Elution Fractionation (TREF), as described in Wild, et al., J. Poly. Sci. Poly. Phys. Ed., vol. 20, p. 441 (1982), which is incorporated herein by reference.
To determine CDBI, a solubility distribution curve is first generated for the copolymer. This may be accomplished using data acquired from TREF techniques described above. This solubility distribution curve is a plot of the weight fraction of the copolymer that is solubilized as a function of temperature. This is converted to a weight fraction versus composition distribution curve. For the purpose of simplifying the correlation of composition with elution temperature the weight fractions less than 15,000 are ignored. These low weight fractions generally represent a trivial portion of the plastomer of the present invention. The remainder of this description and the appended claims maintain the convention of ignoring weight fractions below 15,000 in the CDBI measurements. For further details regarding the determination of CDBI of a copolymer which are known to those skilled in the art, see, for example, PCT Patent Application WO 93/03093, published Feb. 18, 1993.
The ethylene-based polymers preferably have a melt index, I2.16, of about 0.05 to about 0.50 g/10 min., particularly 0.08 to 0.35 g/10 min., or 0.10 to 0.30 g/10 min., more particularly 0.15 to 0.35 g/10 min., as determined in accordance with ASTM D-1238 under a load of 2.16 kg and at a temperature of 190° C. Some ethylene-based polymers also have a high-load melt index, I2.16, of about 5.0 to about 20.0 g/10 min., particularly about 7.0 to about 15.0 g/10 min., more particularly about 9.0 to about 12.0 g/10 min., as determined in accordance with ASTM D-1238 under a load of 21.6 kg and at a temperature of 190° C. The melt index ratio (I2.16/I2.16) of the ethylene-based polymers has a lower limit of about 10.0 and an upper limit of about 400.0. The lower limit on the melt index ratio may be 15.0, 20.0, 30.0, 40.0, 50.0, 55.0, 60.0, 65.0, or 70.0. The upper limit on the melt index ratio may be 300.0, 200.0 100.0, 95.0, 90.0, 80.0, 75.0, or 70.0. Any combination of lower and upper limits should be considered to be disclosed by the above limits on the melt index ratio, e.g., 10.0 to 400.0, 40.0 to 200.0, 50.0 to 100.0, 60.0 to 80.0, etc.
Particular ethylene-based polymers have a density of from about 0.925 to about 0.955 g/cm3; more particularly 0.930 to 0.950 g/cm3, or 0.935 to 0.945 g/cm3, determined using chips cut from plaques compression molded in accordance with ASTM D-1928 Procedure C, aged in accordance with ASTM D-618 Procedure A, and measured as specified by ASTM D-1505.
Typically, although not necessarily, ethylene-based polymers have a molecular weight distribution (MWD, defined as Mw/Mn) of about 2.5 to about 5.5, preferably 4.0 to is 5.0. The expression Mw/Mn is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn). The weight average molecular weight is given by:
The number average molecular weight is given by:
The z-average molecular weight is given by:
where ni in the foregoing equations is the number fraction of molecules of molecular weight Mi. Measurements of Mw, Mz, and Mn are typically determined by Gel Permeation Chromatography as disclosed in Macromolecules, Vol. 34, No. 19, p. 6812 (2001).
Ethylene-based polymers may also be characterized by an averaged 1% secant modulus (M) of from 10,000 to 60,000 psi (pounds per square inch), and a relation between M and the dart drop impact strength in g/mil (DIS) complying with formula (A):
DIS≧0.8*[100+e(11.71−0.000268 M+2.183×10
where “e” represents 2.7183, the base Napierian logarithm, M is the averaged modulus in psi, and DIS is the 26 inch dart impact strength. The DIS is preferably from about 120 to about 1000 g/mil, even more preferably, from about 150 to about 800 g/mil.
The relationship of the Dart Impact Strength to the averaged 1% secant modulus is thought to be an indicator of long-chain branching in the ethylene-based polymer. Thus, alternatively ethylene-based polymers of certain embodiments may be characterized as having long-chain branches. Long-chain branches for the purposes of this invention represent the branches formed by reincorporation of vinyl-terminated macromers, not the branches formed by incorporation of the comonomers. The number of carbon atoms on the long-chain branches ranges from a chain length of at least one carbon more than two carbons is less than the total number of carbons in the comonomer to several thousands. For example, a long-chain branch of an ethylene/hexene ethylene-based polymer is at least five (5) carbons in length (i.e., 6 carbons less 2 equals 4 carbons plus one equals a minimum branch length of five carbons for long-chain branches). Particular ethylene-based polymers have a 0.05 to 1.0, particularly 0.05 to 0.5, 0.1 to 0.4, or 0.2 to 0.3, long-chain branches per 1000 carbon atoms. Ethylene-based polymers having levels of long-chain branching greater than 1.0 long-chain branch per 1000 carbon atoms may have some beneficial properties, e.g., improved processability, shear thinning, and/or delayed melt fracture, and/or improved melt strength.
Various methods are known for determining the presence of long-chain branches. For example, long-chain branching can be determined using 13C nuclear magnetic resonance (NMR) spectroscopy and to a limited extent, e.g., for ethylene homopolymers and for certain copolymers, and it can be quantified using the method of Randall (Journal of Macromolecular Science, Rev. Macromol. Chem. Phys., C29 (2&3), pp. 285-297). Although conventional 13C NMR spectroscopy cannot determine the length of a long-chain branch in excess of about six carbon atoms, there are other known techniques useful for quantifying or determining the presence of long-chain branches in ethylene-based polymers, such as ethylene/1-octene interpolymers. For those ethylene-based polymers wherein the 13C resonances of the comonomer overlap completely with the 13C resonances of the long-chain branches, either the comonomer or the other monomers (such as ethylene) can be isotopically labeled so that the long-chain branches can be distinguished from the comonomer. For example, a copolymer of ethylene and 1-octene can be prepared using 13C-labeled ethylene. In this case, the resonances associated with macromer incorporation will be significantly enhanced in intensity and will show coupling to neighboring 13C carbons, whereas the octene resonances will be unenhanced.
Alternatively, the degree of long-chain branching in ethylene-based polymers may be quantified by determination of the branching index. The branching index g′ is defined by the following equation:
where g′ is the branching index, IVBr is the intrinsic viscosity of the branched ethylene-based polymer and IVLin is the intrinsic viscosity of the corresponding linear ethylene-based polymer having the same weight average molecular weight and molecular weight distribution as the branched ethylene-based polymer and, in the case of copolymers and terpolymers, substantially the same relative molecular proportion or proportions of monomer units. For the purposes, the molecular weight and molecular weight distribution are considered “the same” if the respective values for the branched polymer and the corresponding linear polymer are within 10% of each other. Preferably, the molecular weights are the same and the MWD of the polymers are within 10% of each other. A method for determining intrinsic viscosity of polyethylene is described in Macromolecules, 2000, 33, pp. 7489-7499. Intrinsic viscosity may be determined by dissolving the linear and branched polymers in an appropriate solvent, e.g., trichlorobenzene, typically measured at 135° C. Another method for measuring the intrinsic viscosity of a polymer is ASTM D-5225-98-Standard Test Method for Measuring Solution Viscosity of Polymers with a Differential Viscometer, which is incorporated by reference herein in its entirety.
The branching index, g′, is inversely proportional to the amount of branching. Thus, lower values for g′ indicate relatively higher amounts of branching. The amounts of short and long-chain branching each contribute to the branching index according to the formula: g′=g′LCB×g′SCB. Thus, the branching index due to long-chain branching may be calculated from the experimentally determined value for g′ as described by Scholte, et al., in J. App. Polymer Sci., 29, pp. 3763-3782 (1984), incorporated herein by reference.
While any suitable polymerization method (including solution or slurry polymerization methods) may be used, the ethylene-based polymers of the present invention may be readily obtained via a continuous gas phase polymerization using supported catalyst comprising an activated molecularly discrete catalyst in the substantial absence of an aluminum alkyl based scavenger (e.g., triethylaluminum (TEAL), trimethylaluminum (TMAL), triisobutyl aluminum (TIBAL), tri-n-hexylaluminum (TNHAL), and the like).
Ethylene-based polymers of the invention can be made with zirconium transition metal metallocene-type catalyst systems. Non-limiting examples of metallocene catalysts and catalyst systems useful in practicing the present invention include those described in, U.S. Pat. Nos. 5,466,649, 6,476,171, 6,225,426, and 7,951,873; and in the references cited therein, all of which are fully incorporated herein by reference. Particularly useful catalyst systems include supported dimethylsilyl bis(tetrahydroindenyl) zirconium dichloride.
Supported polymerization catalyst may be deposited on, bonded to, contacted with, or incorporated within, adsorbed or absorbed in, or on, a support or carrier. In another embodiment, the metallocene is introduced onto a support by slurrying a presupported activator in oil, a hydrocarbon such as pentane, solvent, or non-solvent, then adding the metallocene as a solid while stirring. The metallocene may be finely divided solids. Although the metallocene is typically of very low solubility in the diluting medium, it is found to distribute onto the support and be active for polymerization. Very low solubilizing media such as mineral oil (e.g., Kaydo™ or Drakol™) or pentane may be used. The diluent can be filtered off and the remaining solid shows polymerization capability much as would be expected if the catalyst had been prepared by traditional methods such as contacting the catalyst with methylalumoxane in toluene, contacting with the support, followed by removal of the solvent. If the diluent is volatile, such as pentane, it may be removed under vacuum or by nitrogen purge to afford an active catalyst. The mixing time may be greater than 4 hours, but shorter times are suitable.
Typically in a gas phase polymerization process, a continuous cycle is employed where in one part of the cycle of a reactor, a cycling gas stream, otherwise known as a recycle stream or fluidizing medium, is heated in the reactor by the heat of polymerization. This heat is removed in another part of the cycle by a cooling system external to the reactor. (See for example U.S. Pat. Nos. 4,543,399, 4,588,790, 5,028,670, 5,317,036, 5,352,749, 5,405,922, 5,436,304, 5,453,471, 5,462,999, 5,616,661, and 5,668,228 all of which are fully incorporated herein by reference.)
Generally, in a gas fluidized bed process for producing polymers, a gaseous stream containing one or more monomers is continuously cycled through a fluidized bed in the presence of a catalyst under reactive conditions. The gaseous stream is withdrawn from the fluidized bed and recycled back into the reactor. Simultaneously, polymer product is withdrawn from the reactor and fresh monomer is added to replace the polymerized monomer. The reactor pressure may vary from 100 psig (680 kPag)-500 psig (3448 kPag), or in the range of from 200 psig (1379 kPag)-400 psig (2759 kPag), or in the range of from 250 psig (1724 kPag)-350 psig (2414 kPag). The reactor operated at a temperature in the range of 60° C. to 120° C., 60° C. to 115° C., 70° C. to 110° C., 70° C. to 95° C., or 85° C. to 95° C. The productivity of the catalyst or catalyst system is influenced by the main monomer partial pressure. The mole percent of the main monomer, ethylene, is from 25.0-90.0 mole percent, or 50.0-90.0 mole percent, or 70.0-85.0 mole percent, and the monomer partial pressure is in the range of from 75 psia (517 kPa)-300 psia (2069 kPa), or 100-275 psia (689-1894 kPa), or 150-265 psia (1034-1826 kPa), or 200-250 psia (1378-1722 kPa), which are typical conditions in a gas phase polymerization process.
Other gas phase processes contemplated by the process of the invention include those described in U.S. Pat. Nos. 5,627,242, 5,665,818 and 5,677,375, and European published patent applications EP-A-0 794 200, EP-A-0 802 202 and EP-B-634 421 all of is which are herein fully incorporated by reference.
It may be beneficial in slurry or gas phase processes, to operate in the substantial absence of or essentially free of any scavengers, such as triethylaluminum, trimethylaluminum, triisobutylaluminum, and tri-n-hexylaluminum and diethyl aluminum chloride and the like. Such processes are described in PCT Publication WO 96/08520, which is herein fully incorporated by reference.
Additionally, the use of a process continuity aid, while not required, may be desirable in any of the foregoing processes. Such continuity aids are well known to persons of skill in the art and include, for example, metal stearates.
Ethylene-based polymers described herein can be blended with another polymer components, particularly other alpha-olefin polymers such as polypropylene and/or polyethylene homopolymer and copolymer compositions (e.g., LLDPE, HDPE, MDPE, LDPE, and other differentiated polyethylenes). The ethylene-based polymer may be present in such blends in an amount of from 0.1 to 99.9 wt. %. The upper limit on the amount of ethylene-based polymer in such blends may be 99.5 wt. %, 99.0 wt. %, 98.0 wt. %, 97.0 wt. %, 96.0 wt. %, 95.0 wt. %, 90.0 wt. %, 85.0 wt. %, 80.0 wt. %, 75.0 wt. %, 70.0 wt. %, 60.0 wt. %, 50.0 wt. %, 40.0 wt. %, 30.0 wt. %, 25.0 wt. %, 20.0 wt. %, 15.0 wt. %, 10.0 wt. %, 5.0 wt. %, 4.0 wt. %, 3.0 wt. %, 2.0 wt. %, 1.0 wt. %, or 0.5 wt. %. The lower limit on the amount of ethylene-based polymer in such blends may be 99.5 wt. %, 99.0 wt. %, 98.0 wt. %, 97.0 wt. %, 96.0 wt. %, 95.0 wt. %, 90.0 wt. %, 85.0 wt. %, 80.0 wt. %, 75.0 wt. %, 70.0 wt. %, 60.0 wt. %, 50.0 wt. %, 40.0 wt. %, 30.0 wt. %, 25.0 wt. %, 20.0 wt. %, 15.0 wt. %, 10.0 wt. %, 5.0 wt. %, 4.0 wt. %, 3.0 wt. %, 2.0 wt. %, 1.0 wt. %, or 0.5 wt. %. Blend compositions including any upper and lower limit of ethylene-based polymer are envisioned (e.g., 0.5 to 99.5 wt. %, 10.0 to 90.0 wt. %, 20.0 to 80.0 wt. %, 25.0 to 75.0 wt. %, 40.0 to 60.0 wt. %, 45.0 to 55.0 wt. %, 5.0 to 50.0 wt. %, 10.0 to 40.0 wt. %, 20.0 to 30.0 wt. %, 50.0 to 95.0 wt. %, 60.0 to 90.0 wt. %, 70.0 to 80.0 wt. %, 1.0 to 15.0 wt. %, 1.0 to 10.0 wt. %, 1.0 to 5.0 wt. %, 85.0 to 99.0 wt. %, 90 to 99.0 wt. %, or 95.0 to 99.0 wt %). The amount of ethylene-based polymer is based on the total weight of the polymer blend.
In certain embodiments, the ethylene-based polymer may be blended with one or more propylene-based polymers (e.g., homopolymer, copolymer, or impact copolymer including >50.0 mol % of polymer units derived from propylene). In addition to blends having the compositional limits described above, particularly useful polypropylene-containing blends comprise less than 50.0 wt. % (e.g. 2.0 to 49.5 wt. %, 5.0 to 45.0 wt. %, 7.5 to 42.5 wt. % 10.0 to 40.0 wt. 20.0 to 30.0 wt. %, 25.0 to 49.5 wt. % 30.0 to 49.5 wt. %, 35.0 to is 45.0 wt. %) propylene-based polymer. Some useful propylene-based polymers include those having one or more of the following properties:
1) propylene content of at least 85 wt. % (preferably at least 90 wt. %, preferably at least 95 wt. %, preferably at least 97 wt. %, preferably 100 wt %); and/or
2) Mw of 30 to 2,000 kg/mol (preferably 50 to 1,000 kg/mol, preferably 90 to 500 kg/mol); and/or
3) Mw/Mn of 1 to 40 (preferably 1.4 to 20, preferably 1.6 to 10, preferably 1.8 to 3.5, preferably 1.8 to 2.5); and/or
4) branching index (g′) of 0.2 to 2.0 (preferably 0.5 to 1.5, preferably 0.7 to 1.3, preferably 0.9 to 1.1); and/or
5) melt flow rate (MFR) of 1 to 300 dg/min (preferably 5 to 150 dg/min, preferably 10 to 100 dg/min, preferably 20 to 60 dg/min); and/or
6) melting point (Tm, peak second melt) of at least 100° C. (preferably at least 110° C., preferably at least 120° C., preferably at least 130° C., preferably at least 140° C., preferably at least 150° C., preferably at least 160° C., preferably at least 165° C.); and/or
7) crystallization temperature (Tc, peak) of at least 70° C. (preferably at least 90° C., preferably at least 110° C., preferably at least 130° C.); and/or
8) heat of fusion (Hf) of 40 to 160 J/g (preferably 50 to 140 J/g, preferably 60 to 120 J/g, preferably 80 to 100 J/g); and/or
9) crystallinity of 5 to 80% (preferably 10 to 75%, preferably 20 to 70%, preferably 30 to 65%, preferably 40 to 60%); and/or
10) propylene meso diads of 90% or more (preferably 92% or more, preferably 94% or more, preferably 96% or more); and/or
11) heat deflection temperature (HDT) of 45 to 140° C. (preferably 60 to 135° C., preferably 75 to 125° C.); and/or
12) Gardner impact strength at 23° C. of 30 to 1300 J (preferably 40 to 800 J, preferably 50 to 600 J); and/or
13) flexural modulus of 300 to 3000 MPa (preferably 600 to 2500 MPa, preferably 800 to 2000 MPa, preferably 1000 to 1500 MPa).
In a preferred embodiment, the propylene polymer is selected from polypropylene homopolymer, polypropylene copolymers, and blends thereof The homopolymer may be atactic polypropylene, isotactic polypropylene, highly isotactic polypropylene, syndiotactic polypropylene, and blends thereof The copolymer can be a random copolymer, a statistical copolymer, a block copolymer, and blends thereof
The method of making the polypropylene is not critical, as it can be made by slurry, solution, gas-phase, high-pressure, or other suitable processes, through the use of catalyst systems appropriate for the polymerization of polyolefins, such as Ziegler-Natta-type catalysts, metallocene-type catalysts, other appropriate catalyst systems or combinations thereof In a preferred embodiment the propylene polymers are made by the catalysts, activators and processes described in U.S. Pat. Nos. 5,741,563, 6,342,566, 6,384,142, and PCT Publication Nos. WO 03/040201 and WO 97/19991. Such catalysts are well known in the art, and are described in, for example, Z
Polypropylene homopolymers or copolymers useful in the present invention may have some level of isotacticity or syndiotacticity. In one embodiment, the polypropylene is isotactic polypropylene, and in another embodiment, the polypropylene is highly isotactic polypropylene. In a desirable embodiment, the polypropylene is a polypropylene homopolymer having at least 85% (preferably at least 90%) isotactic pentads. In another desirable embodiment, the polypropylene is a polypropylene homopolymer having at least 85% (preferably at least 90%) syndiotactic pentads.
In a particularly preferred embodiment, the propylene polymers useful herein are produced by a metallocene catalyst system, and have a Mw/Mn of 1.5 to 3 (preferably 1.8 to 2.5) and a CDBI of 80 wt. % or more (preferably 90 wt. % or more).
In another embodiment the propylene polymer is a random copolymer, also known as an “RCP,” comprising propylene and up to 20 mole % of ethylene or a C4 to C20 olefin, preferably up to 20 mole % ethylene, preferably from 1 to 10 mole % ethylene.
The blends may be formed using conventional equipment and methods, such as by dry blending the individual components and subsequently melt mixing in a mixer, or by mixing the components together directly in a mixer, such as, for example, a Banbury mixer, a Haake mixer, a Brabender internal mixer, or a single or twin-screw extruder, which may include a compounding extruder and a side-arm extruder used directly downstream of a polymerization process. Additionally, additives may be included in the blend, in one or more components of the blend, and/or in a product formed from the blend, such as a film, as desired. Such additives are well known in the art, and can include, for example: fillers; is antioxidants (e.g., hindered phenolics such as IRGANOX™ 1010 or IRGANOX™ 1076 available from Ciba-Geigy); phosphites (e.g., IRGAFOS™ 168 available from Ciba-Geigy); anti-cling additives; tackifiers, such as polybutenes, terpene resins, aliphatic and aromatic hydrocarbon resins, alkali metal and glycerol stearates and hydrogenated rosins; UV stabilizers; heat stabilizers; antiblocking agents; release agents; anti-static agents; pigments; colorants; dyes; waxes; silica; fillers; talc and the like.
Ethylene-based polymer and blends thereof may be used in a variety of end-use applications. Films comprising ethylene-based polymers are particularly useful. Such films include, for example, monolayer and multilayer blown, extruded, and/or cast stretch and/or shrink films. Film applications improved by higher melt strength, e.g., thick film and geomembrane applications, may be particularly benefitted. Films including the ethylene-based polymer are also useful as cling film, sealing films, oriented films, snack packaging, heavy duty bags, grocery sacks, baked and frozen food packaging, medical packaging, industrial liners, membranes, etc., in food-contact and non-food contact applications.
The total thickness of monolayer and multilayer films may vary based upon the application desired. A total film thickness of about 5-100 μm, more typically about 10-50 μm, is suitable for most applications. In some applications, particularly geomembrane applications, the films may have a thickness of 100 μm to 5.0 mm, particularly 1.0 to 5.0 mm, or 2.0 to 4.0 mm. Those skilled in the art will appreciate that the thickness of individual layers for multilayer films may be adjusted based on desired end-use performance, resin or copolymer employed, equipment capability, and other factors. The materials forming each layer may be coextruded through a coextrusion feedblock and die assembly to yield a film with two or more layers adhered together but differing in composition. Coextrusion can be adapted for use in both cast film or blown film processes.
Particular embodiments of the invention related to monolayer films comprising an ethylene-based polymer according to the invention. When used in multilayer films, the ethylene-based polymer may be used in any layer of the film, or in more than one layer of the film, as desired. When more than one layer of the film comprises an ethylene-based polymer, each such layer can be individually formulated; i.e., the layers comprising the ethylene-based polymer can be the same or different chemical composition, density, melt index, thickness, etc., depending upon the desired properties of the film.
To facilitate discussion of different film structures, the following notation is used herein. Each layer of a film is denoted “A” or “B”, where “A” indicates a conventional film layer as defined below, and “B” indicates a film layer comprising an ethylene-based polymer is (or blend including an ethylene-based polymer). Where a film includes more than one A layer or more than one B layer, one or more prime symbols (′, ″, ′″, etc.) are appended to the A or B symbol to indicate layers of the same type (conventional or inventive) that can be the same or can differ in one or more properties, such as chemical composition, density, melt index, thickness, etc. Finally, the symbols for adjacent layers are separated by a slash (/). Using this notation, a three-layer film having an inner layer of a LLDPE polymer blend disposed between two outer, conventional film layers would be denoted A/B/A′. Similarly, a five-layer film of alternating conventional/inventive layers would be denoted A/B/A′/B′/A″. Unless otherwise indicated, the left-to-right or right-to-left order of layers does not matter, nor does the order of prime symbols; e.g., an A/B film is equivalent to a B/A film, and an A/A′/B/A″ film is equivalent to an A/B/A′/A″ film. The relative thickness of each film layer is similarly denoted, with the thickness of each layer relative to a total film thickness of 100 (dimensionless) indicated numerically and separated by slashes; e.g., the relative thickness of an A/B/A′ film having A and A′ layers of 10 μm each and a B layer of 30 μm is denoted as 20/60/20.
For the various films described herein, the “A” layer can comprise any material known in the art for use in multilayer films or in film-coated products. Thus, for example, each A layer can be formed of a polyethylene homopolymer or copolymer, and the polyethylene can be, for example, a VLDPE, a LDPE, a LLDPE, a MDPE, a HDPE, or a DPE, as well as other polyethylenes known in the art. The polyethylene can be produced by any suitable process, including metallocene-catalyzed processes and Ziegler-Natta catalyzed processes. Further, each A layer can be a blend of two or more such polyethylenes and can include additives known in the art. Further, one skilled in the art will understand that the layers of a multilayer film must have the appropriate viscosity match. Examples of suitable A layers are described in US2008/0038533, filed Apr. 24, 2007, the disclosure of which is incorporated herein by reference in its entirety.
The “B” layer comprises an ethylene-based polymer or blend thereof, and can be any of such blends described herein. In some embodiments, the B layer consists essentially of an ethylene-based polymer. In other embodiments, the B layer consists essentially of two or more ethylene-based polymers. In still other embodiments, the B layer comprises (a) from 0.1 to 99.9 wt. %, 10.0 to 90.0 wt. %, 20.0 to 80.0 wt. %, 30.0 to 70.0 wt. %, 40.0 to 60.0 wt. %, or 45.0 to 55.0 wt. % of an ethylene-based polymer as described herein; and (b) from 99.9 to 0.1 wt. %, 90.0 to 10.0 wt. %, 80.0 to 20.0 wt. %, 70.0 to 30.0 wt. %, 60.0 to 40.0 wt. %, or 55.0 to 45.0 wt. %, of a polymer selected from the group consisting of very low density is polyethylene, medium density polyethylene, differentiated polyethylene, and combinations thereof, wherein the wt. % values are based on the total weight of the film.
In certain embodiments, particularly those related to sheeting applications where a balance of high gloss and high scratch resistance is desired, the multilayer film has a structure where at least one outer layer of the film is a B layer, e.g., B/A/A′, B/A/B, B/A/B′ etc. The thickness of each layer of the film, and of the overall film, is not particularly limited, but is determined according to the desired properties of the film. Typical film layers have a thickness of from about 1 to about 1000 μm, more typically from about 5 to about 100 μm, and typical films have an overall thickness of from about 10 to about 100 μm.
Some films including ethylene-based polymers of the invention are characterized by unique properties. For example, some films comprising ethylene-based polymers have one or more of the following gloss values: a 20° Gloss of 5.0 to 15.0, preferably 7.5 to 15.0; a 60° Gloss of 30.0 to 60.0, preferably 40.0 to 60.0; and/or an 80° Gloss of 60.0 to 80.0, preferably 70.0 to 80.0. Gloss, a dimensionless number, is measured as specified by ASTM D-2457 at the reported angles.
Some multilayer films have a particular combination of tear resistance and shrink properties. For example, a multilayer film comprising opposing outer layers A in surface contact with a core layer comprising an ethylene-based polymer has a TD shrink of 20.0 to 70.0%. Some such films have an Elmendorf Tear of 0.5 to 10.0 g/μm. In particular such embodiments, the outer layers A comprise an ethylene copolymer having at least 50 wt. % ethylene-derived units and up to 50 wt. %, preferably 1 wt. % to 35 wt. %, even more preferably 1 wt. % to 6 wt. % of a C3 to C20 comonomer (preferably hexene or octene), based upon the weight of the copolymer. The polyethylene copolymers preferably have a composition distribution breadth index (CDBI) of 60% or more, preferably 60% to 80%, preferably 65% to 80%. In another preferred embodiment, the ethylene copolymer has a density of 0.910 to 0.950 g/cm3 (preferably 0.915 to 0.930 g/cm3, preferably 0.915 to 0.923 g/cm3), a CDBI of 60% to 80%, preferably between 65% and 80%, and a melt index, I2.16 of about 0.5 to 5.0 g/10 min. Preferably these polymers are metallocene polyethylenes (mPEs). Such ethylene copolymers are available from ExxonMobil Chemical Company under the tradename Exceed™ mPEs. Other outer layers A comprise an mPE having at least some amount of long-chain branching; a CBDI≧70.0, a density of 0.910 to 0.950 g/cm3 (preferably 0.915 to 0.940 g/cm3, preferably 0.918 to 0.923 g/cm3), a melt index of about 0.1 to 3.0 g/min. Some such mPEs are available from ExxonMobil Chemical Company under the tradename Enable™ mPE resins.
Such films may be formed by any number of well-known extrusion or coextrusion techniques discussed below. Films may be unoriented, uniaxially oriented or biaxially oriented. Physical properties of the film may vary depending on the film forming techniques used.
One technique for making film structures described above, and for which the ethylene-based polymers are particularly suitable, is a high-stalk blown film processes. One such process comprises 1) providing an ethylene-based polymer described above and 2) extruding the ethylene-based polymer through an annular die to form an extruded tube of molten material. The tube has a tube diameter that is substantially the annular die diameter. However, while continuously extruding the tube, the tube of molten material expands downstream of said annular die to form a bubble. The bubble diameter may then exceed (i) the annular die diameter and (ii) the tube diameter. The bubble has a frost line which comprises a demarcation line between said molten material and solid biaxially oriented film. The frost line is located on the bubble at a height of least 5.0, preferably 10.0, preferably 20.0 times the die diameter. The ethylene-based polymers are particularly suitable in such processes, having a neck-height-ratio (neck height/die diameter) from 2.0 to 12.0, preferably from 4.0 to 12.0, more preferably 6.0 to 12.0 and/or a blow-up-ratio (BUR, bubble diameter/die diameter) from 2.0 to 8.0, preferably 3.0 to 8.0, more preferably, 4.0 to 8.0, more preferably still 6.0 to 8.0.
In other words, high-stalk blown film processes may benefit from ethylene-based polymers comprising about 80.0 to 99.0 wt. % of polymer units derived from ethylene and about 1.0 to about 20.0 wt. % of polymer units derived from one or more C3 to C20 α-olefin comonomers where such polymers have a complex modulus, G*60, <2.50×103 Pa, preferably <2.00×103 Pa. Preferably the ethylene-based polymer has a complex modulus, G*50, <50.00×103 Pa, preferably <25.00×103 Pa, preferably <20.00×103 Pa, preferably <10.00×103 Pa, preferably <5.00×103 Pa, and one or more of the following: a CDBI≧70.0%, preferably ≧80.0%, preferably ≧85.0%, preferably ≧90.0%; a melt index, I2.16, of about 0.05 to about 0.50 g/10 min., preferably 0.08 to 0.35 g/10 min., more preferably 0.10 to 0.30 g/10 min.; a density of from about 0.930 to about 0.950 g/cm3; preferably 0.935 to 0.945 g/cm3and/or a MWD of about 2.5 to about 5.5, preferably 4.0 to 5.0.
In another aspect, the ethylene-based polymers described herein may be suitable for methods of making pipe for transmission or distribution of water and gases. In other words, the method of making the pipe includes selecting an ethylene-based polymer is described herein to make a pipe by any known methods, some of which are described in U.S. Pat. Nos. 6,204,349; 6,191,227; 5,908,679; 5,683,767; 5,417,561; and 5,290,498, the disclosures of all of the preceding patents are incorporated by reference in their entirety.
An ethylene-based polymer comprising about 80.0 to 99.0 wt. % of polymer units derived from ethylene and about 1.0 to about 20.0 wt. % of polymer units derived from one or more C3 to C20 α-olefin comonomers; the ethylene-based polymer having a complex modulus, G*60, <2.50×103 Pa, preferably <2.00×103 Pa.
An ethylene-based polymer comprising about 80.0 to 99.0 wt. % of polymer units derived from ethylene and about 1.0 to about 20.0 wt. % of polymer units derived from one or more C3 to C20 α-olefin comonomers; the ethylene-based polymer having a CDBI≧70.0%, preferably ≧80.0%, preferably ≧85.0%, preferably ≧90.0%; a melt index, I2.16, of about 0.05 to about 0.50 g/10 min.; a density of from about 0.930 to about 0.950 g/cm3; and a MWD of about 2.5 to about 5.5, preferably 4.0 to 5.0, preferably having a complex modulus, G*60, <2.50×103 Pa, preferably <2.00×103 Pa.
An ethylene-based polymer comprising about 80.0 to 99.0 wt. % of polymer units derived from ethylene and about 1.0 to about 20.0 wt. % of polymer units derived from one or more C3 to C20 α-olefin comonomers; the ethylene-based polymer having a local maximum loss angle at a complex modulus, G*, of 2.50×104 to 1.00×106 Pa, preferably 2.50×104 to 1.00×105 Pa and a local minimum loss angle at a complex modulus, G*, of 1.00×104 to 3.00×104 Pa, preferably 1.25×104 to 2.00×104 Pa.
The ethylene-based polymer of any of Embodiments A to C, wherein the ethylene-based polymer has a density of 0.935 to 0.945 g/cm3.
The ethylene-based polymer of any of Embodiments A to D, wherein the ethylene-based polymer has a melt index, I2.16, of 0.08 to 0.35 g/10 min., preferably 0.10 to 0.30 g/10 min.
The ethylene-based polymer of any of Embodiments A to E, wherein the ethylene-based polymer has a 20° Gloss of 5.0 to 15.0.
The ethylene-based polymer of any of Embodiments A to F, wherein the ethylene-based polymer has a 60° Gloss of 30.0 to 60.0.
The ethylene-based polymer of any of Embodiments A to G, wherein the ethylene-based polymer has an 80° Gloss of 60.0 to 80.0.
The ethylene-based polymer of any of Embodiments A to H having a complex modulus, G*50, <50.00×103 Pa, preferably <25.00×103 Pa, preferably <20.00×103 Pa, preferably <10.00×103 Pa, preferably <5.00×103 Pa.
The ethylene-based polymer of any of Embodiments A to I, wherein the local maximum loss angle is from 40.0 to 50.0°, preferably, 40.0 to 45.0°, more preferably 42.5 to 45.0°.
The ethylene-based polymer of any of Embodiments A to J, wherein the local minimum loss angle is from 40.0 to 50.0°, preferably, 40.0 to 45.0°, more preferably 40.0 to 42.5°.
The ethylene-based polymer of any of Embodiments A to K, comprising 1.0 to 5.0 wt. %, particularly 1.0 to 3.0 wt. % of polymer units derived from one or more C3 to C20 α-olefin comonomers, preferably C3 to C10 α-olefins, and more preferably C4 to C8 α-olefins, most preferably hexene-1.
An article of manufacture comprising an ethylene-based polymer according to any of Embodiments A to L, wherein said article is formed by a manufacturing process selected from the group consisting of injection molding, blow molding, extrusion coating, foaming, casting, and combinations thereof
An article of manufacture comprising an ethylene-based polymer according to any of Embodiments A to L, wherein said article comprises a thermoformed extruded sheet.
An article of manufacture of Embodiment N wherein the thermoformed extruded sheet is a multilayer extruded sheet having a cap layer comprising the ethylene/alpha-olefin of any of Embodiments A to L.
An article of manufacture of Embodiment M, wherein said article is an extruded monolayer film.
An article of manufacture of Embodiment M, wherein said article is an extruded multilayer film.
A multilayer film comprising an outer layer A in surface contact with a first surface of a core layer comprising an ethylene-based polymer according to any of Embodiments A to L, a second surface of the core layer in surface contact with a layer B, wherein the multilayer film has a TD shrink of 20.0 to 70.0%.
The multilayer film of Embodiment R having a MD Elmendorf Tear of 0.5 to 10.0 g/μm.
The multilayer film of Embodiment R or S, wherein the ethylene-based polymer has 0.05 to 0.5 long-chain branches per/1000 C atoms.
A polymer blend composition comprising 1) 0.1 to 99.9 wt. % of an ethylene-based polymer according to any of Embodiments A to L; and 2) 0.1 to 99.9 wt. % of a polymer selected from the group consisting of high density polyethylene, linear low density polyethylene, low density polyethylene, medium density polyethylene, differentiated polyethylene and combinations thereof. Blends including polypropylene homopolymers and copolymers, including impact copolymers, and combinations thereof are also particularly useful in some applications.
A process for producing a film, comprising 1) providing an ethylene-based polymer of any of Embodiments A to L or blend thereof and 2) extruding the ethylene-based polymer or blend thereof through an annular die to form an extruded tube of molten material to provide the tube with a tube diameter which is substantially the annular die diameter; while continuously extruding the tube, expanding the tube, downstream of said annular die, to attenuate the walls thereof to form the tube of molten material into a bubble of a bubble diameter which exceeds (i) the annular die diameter and (ii) the tube diameter; wherein said bubble has a frost line which comprises a demarcation line between said molten material and solid biaxially oriented film; said frost line located on the bubble at a height of least 5, preferably 10, preferably 20 times the die diameter.
The process of Embodiment V, wherein the ethylene-based polymer comprises about 80.0 to 99.0 wt. % of polymer units derived from ethylene and about 1.0 to about 20.0 wt. % of polymer units derived from one or more C3 to C20 α-olefin comonomers; the ethylene-based polymer having a complex modulus, G*60, <2.50×103 Pa, preferably <2.00×103 Pa.
The process of Embodiment V or Embodiment W, wherein the ethylene-based polymer has a complex modulus, G*50, <50.00×103 Pa, preferably <25.00×103 Pa, preferably <20.00×103 Pa, preferably <10.00×103 Pa, preferably <5.00×103 Pa.
The process of any of Embodiments V to X, wherein the ethylene-based polymer has a CDBI≧70.0%, preferably ≧80.0%, preferably ≧85.0%, preferably ≧90.0%; a melt index, I2.16, of about 0.05 to about 0.50 g/10 min.; a density of from about 0.930 to about 0.950 g/cm3; and a MWD of about 2.5 to about 5.5, preferably 4.0 to 5.0.
The process of any of Embodiments V to Y, wherein the ethylene-based polymer has a density of 0.935 to 0.945 g/cm3.
The process of any of Embodiments V to Z, wherein the ethylene-based polymer has a melt index, I2.16, of 0.08 to 0.35 g/10 min., preferably 0.10 to 0.30 g/10 min.
The process of any of Embodiments V to AA wherein the Neck-Height-Ratio (Neck Height/Die Diameter) is from 2.0 to 12.0.
The process of any of Embodiments U to AB, wherein the Blow-Up-Ratio (BUR, Bubble Diameter/Die Diameter) is from 2.0 to 8.0.
The properties described herein can be determined in accordance with the following test procedures. Where any of these properties is referenced in the appended claims, it is to be measured in accordance with the specified test procedure.
Where applicable, the properties and descriptions below are intended to encompass measurements in both the machine and transverse directions. Such measurements are reported separately with the designation “MD” indicating a measurement in the machine direction and “TD” indicating a measurement in the transverse direction.
Gauge, reported in μm, is measured using a Measuretech Series 200 instrument. The instrument measures film thickness using a capacitance gauge. For each film sample, ten film thickness datapoints are measured per inch of film as the film is passed through the gauge in a transverse direction. From these measurements, an average gauge measurement is determined and reported.
Elmendorf Tear, reported in grams (g) or grams per μm (g/μm), is measured as specified by ASTM D-1922.
Haze, reported as a percentage (%), is measured as specified by ASTM D-1003.
Dart Drop Impact or Dart Drop Impact Strength (DIS), reported in grams (g) and/or grams per μm (g/μm), is measured as specified by ASTM D-1709, method A.
Peak Puncture Force, reported in pounds (lb) and/or pounds per μm (lb/mil), is determined according to ASTM D-3763.
Shrink, reported as a percentage, is measured by cutting circular specimens from a film using a 100 mm die. The samples were marked in their respective directions, dusted with talc, and placed on a pre-heated, talc covered tile. The samples were then heated using a heat gun (model HG-501A) for approximately 10 to 45 seconds, or until the dimensional change ceased. An average of three specimens is reported. A negative shrinkage number is indicates expansion of a dimension after heating when compared to its pre-heating dimension.
Where any of the above properties are reported in pounds per square inch, grams per μm, or in any other dimensions that are reported per unit area or per unit thickness, the ASTM methods cited for each property have been followed except that the film gauge is measured in accordance with ASTM D-374, Method C.
Inventive LLDPE resins were prepared using the metallocene catalysts and gas phase processes described above. In particular, preparation of the inventive LLDPEs used in the following examples was substantially as described in the examples set forth in U.S. Pat. No. 6,476,171, which is incorporated by reference herein in its entirety. Process conditions were manipulated as needed to achieve resins having the resulting density and melt index measurements identified below.
Ethylene is polymerized with 1-hexene using the metallocene catalysts and gas phase processes substantially as described in the examples set forth in U.S. Pat. No. 6,476,171, which is incorporated by reference herein in its entirety. Process conditions are manipulated to a polymer having a having a CBDI≧70.0, a density of 0.940 g/cm3, a melt index (I2.16) of 0.15 g/10 min., a melt index ratio (I2.16/I2.16) of 70.0.
A metallocene-catalyzed ethylene-hexene copolymer having a CDBI>60%, a density of 0.918 g/cm3, and a melt index (I2.16) of 1.0 g/10 min., available from ExxonMobil Chemical Company as Exceed™ 1018.
A high molecular weight ethylene copolymer having a density of 0.949 g/cm3, a melt index (I2.16) of 0.10 g/10 min., and a high load melt index (I2.16) of 10 g/10 min., available from ExxonMobil Chemical Company as Paxon™ BA 50-100.
A low density polyethylene with a density of 0.924 g/cm3 and a melt index (I2.16) of 0.7 g/10 min., available from ExxonMobil Chemical Company as LD 071.
A metallocene-catalyzed, long-chain branched, ethylene/1-hexene copolymer having a CBDI≧70.0, a density 0.920 g/cm3, a melt index of about 1.0 g/10 min., and a melt index ratio (I21.6/I2.16) of 34, available from ExxonMobil Chemical Company as Enable™ 20-10.
A metallocene-catalyzed, long-chain branched, ethylene/1-hexene copolymer having a CBDI≧70.0, a density 0.935 g/cm3, a melt index of about 0.5 g/10 min., and a melt index ratio (I21.6/I2.16) of 49, available from ExxonMobil Chemical Company as Enable™ 35-05.
A metallocene-catalyzed, long-chain branched, ethylene/1-hexene copolymer having a CBDI≧70.0, a density 0.920 g/cm3, a melt index of about 0.5 g/10 min., a melt index ratio (I21.6/I2.16) of 38, and available from ExxonMobil Chemical Company as Enable™ 20-05 (CE6).
A metallocene-catalyzed, long-chain branched, ethylene/1-hexene copolymer having a CBDI≧70.0, a density 0.927 g/cm3, a melt index of about 0.5 g/10 min., available from ExxonMobil Chemical Company as Enable™ 27-05.
An ethylene/1-octene plastomer having a CDBI>90%, a density of 0.902 g/cm3, a melt index of 1.1 g/10 min., and available from ExxonMobil Chemical Company as Exact™ 0201.
An ethylene/1-hexene plastomer having a CDBI>90%, a density of 0.86 to 0.925 g/cm3, a melt index of 1.2 g/10 min., and available from ExxonMobil Chemical Company as Exact™ 3132.
A low density polyethylene homopolymer with a density of 0.923 g/cm3 and a melt index (I2.16) of 2.0 g/10 min., available from ExxonMobil Chemical Company as LD105.30.
A low density polyethylene with a density of 0.921 g/cm3 and a melt index (I2.16) of 4.2 g/10 min., available from ExxonMobil Chemical Company as LD201.48.
The rheological properties of Examples 1-6 are examined by the Van Gurp-Palmen treatment. As shown in
Example 1, on the other hand, displays a different behavior. In both high and low ends of the loss angle range, the complex modulus generally decreases. But in an intermediate region, the complex modulus increase to a maximum value before again decreasing. In other words, unlike the Van Gurp-Palmen plot of Examples 2-6, that of Example 1 displays at least one region where the slope is positive. The difference in the loss angle between the local maximum and the local minimum in Example 1 is about 4°, but could be 5.0°, 7.0°, 10.0°, or 15.0° or more in other embodiments. The difference in the complex modulus values between the local maximum and the local minimum in Example 1 is about 52,100 Pa, but it is envisioned that other inventive ethylene-based polymers could, depending on the branching structure of the polymer chains, have a difference that could be greater or less than that observed for Example 1. Van Gurp-Palmen data is collected in Table 1.
modulus of 2,000 Pa. As
A monolayer film comprising the ethylene-based polymer of Example 1 having a thickness of 45 μm is formed in a high-stalk film-forming process at a blow-up ratio (BUR) of 6.6 and a neck height ratio (NHR) of 12.
A monolayer film comprising the ethylene-based polymer of Example 1 having a thickness of 30 μm is formed in a high-stalk film-forming process at a BUR of 3.4 and a NHR of 3.5.
A monolayer film comprising a metallocene-catalyzed, long-chain branched, ethylene/1-hexene copolymer having a CBDI≧70.0, a density 0.927 g/cm3, a melt index of about 0.30 g/10 min., available from ExxonMobil Chemical Company as Enable™ 27-03, and having a thickness of 30 μm is formed in an in-pocket film-forming process at a is BUR of 3.
A monolayer film comprising a high molecular weight, film grade polyethylene having a density of 0.952 g/cm3, a melt index (I2.16) of 0.050 g/10 min., and a high-load melt index (I21.6) of 9.5 g/10 min., available from ExxonMobil Chemical Company as HDPE HTA 001HP2, and having a thickness of 30 μm is formed in a high-stalk film-forming process at a BUR of 4 and a NHR of 8.
The film of Example 16 is substantially repeated except that the film has a thickness of 15 μm.
A monolayer film comprising a polyethylene having a density of 0.950 g/cm3 and a melt index (I2.16) of 0.05 g/10 min., (Formosa HDPE 9001) having a thickness of 20 μm is formed in a high-stalk film-forming process at a BUR of 6 and a NHR of 11.
A 3-layer film having comprising outer layers of an ethylene-propylene-butene terpolymer and a core layer comprising the metallocene-catalyzed, long-chain branched, ethylene/1-hexene copolymer of Example 15. The thickness of each skin layer is 20.0% of the core layer and the total film thickness is 14 μm is formed in a double bubble film-forming process at a BUR of 5.
A monolayer film comprising the metallocene-catalyzed, long-chain branched, ethylene/1-hexene copolymer of Example 15 having a thickness of 30 μm is formed in a high-stalk film-forming process at a BUR of 4 and a NHR of 4.
A monolayer film comprising the metallocene-catalyzed, long-chain branched, ethylene/1-hexene copolymer of Example 15 having a thickness of 15 μm is formed in a high-stalk film-forming process at a BUR of 4 and a NHR of 4.
A monolayer film comprising the metallocene-catalyzed, long-chain branched, ethylene/1-hexene copolymer of Example 6 having a thickness of 15 μm is formed in a high-stalk film-forming process at a BUR of 4 and a NHR of 4.
A 3-layer film having comprising outer layers of the polymer of Example 2 and a core layer comprising ethylene-based polymer of Example 1 having a total film thickness of 30 μm is formed in a high-stalk film-forming process at a BUR of 2.4 and a NHR of 3.5. The thickness of each outer layer is 50.0% of the core layer thickness.
A 3-layer film having comprising outer layers of the polymer of is Example 7 and a core layer comprising ethylene-based polymer of Example 1 having a total film thickness of 30 μm is formed in a high-stalk film-forming process at a BUR of 6.75 and a NHR of 12. The thickness of each outer layer is ⅓ of the core layer thickness.
A 3-layer film having comprising outer layers of the polymer of Example 2 and a core layer comprising ethylene-based polymer of Example 1 having a total film thickness of 15 μm is formed in a high-stalk film-forming process at a BUR of 6.75and a NHR of 12. The thickness of each outer layer is ⅓ of the core layer thickness.
A 3-layer film having comprising outer layers of a metallocene-catalyzed ethylene-hexene copolymer having a CDBI>60%, a density of 0.918 g/cm3and a melt index (I2.16) of 2.0 g/10 min. and available from ExxonMobil Chemical Company as Exceed™ 2018 and a core layer comprising ethylene-based polymer of Example 1 having a total film thickness of 15 μm is formed in a high-stalk film-forming process at a BUR of 6.75and a NHR of 12. The thickness of each outer layer is ⅓ of the core layer thickness.
The properties of the films of Examples 13-26 are collected in Table 2.
In the Examples 27-32, the effect of BUR and NHR conditions on film properties was evaluated for monolayer films of the ethylene-based polymer of Example 1. These results are collected in Table 3.
A two-layer coextrusion film for a geomembrane application comprising essentially the ethylene-based polymer of Example 1 contained in both layers having a thickness of 2 mm is formed in a pocket film-forming process at a blow-up ratio (BUR) of 1.2. 3 wt. % masterbatch was added to provide additional antioxidant and carbon black. The film with a bubble circumference of 7000 mm is extruded at a rate of 750 kg/hr using a die gap of 2.8 mm. The properties of the film of Example 33 are set out in Table 4.
Although the present invention has been described in considerable detail with reference to certain aspects and embodiments thereof, other aspects and embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.
Certain features of the present invention are described in terms of a set of numerical upper limits and a set of numerical lower limits. It should be appreciated that ranges from any lower limit to any upper limit are within the scope of the invention unless otherwise indicated.
All patents, test procedures, and other documents cited in this application are fully incorporated herein by reference for all jurisdictions in which such incorporation is permitted.
The present application claims priority to and the benefit of U.S. Ser. No. 61/733,119, filed Dec. 4, 2012, and EP 13155249.9 filed Feb 14, 2013; U.S. Ser. No. 61/700,966, filed on Sep. 14, 2012 and EP 12191880.9 filed Nov. 8, 2012 entitled, “Ethylene-Based Polymers and Articles Made Therefrom,” the disclosures of which is hereby incorporated by reference herein in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2013/057463 | 8/30/2013 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61700966 | Sep 2012 | US | |
| 61733119 | Dec 2012 | US |
