Patent Application
20170129230
The present invention relates generally to cast films and in some aspects, cast films having improved toughness.
Various polymerization techniques, using different catalyst systems, have been employed to produce ethylene-based polymer compositions suitable for films. Ethylene-based polymer compositions are described in the following references: U.S. Pat. No. 5,844,045 (see also U.S. Pat. No. 5,869,575 and U.S. Pat. No. 6,448,341), U.S. Pat. No. 6,566,446, U.S. Pat. No. 5,677,383 (see also U.S. Pat. No. 6,111,023), U.S. Pat. No. 5,977,251, US2015/0148490, US20150148491 and WO2014/058639. However, there remains a need for compositions that can be used to form films with improved toughness, while maintaining a good balance of other film physical properties, such as tear strength, puncture, and optics.
The present invention utilizes ethylene-based polymers exhibiting certain features in the formation of cast films with desirable properties. For example, in some embodiments, the cast films have improved toughness (e.g., as measured by dart impact strength) as compared to cast films formed from other ethylene-based polymers, while maintaining a good balance of other properties (e.g., tear strength, optical properties, etc.).
In one aspect, the present invention provides a cast film comprising a layer formed from a composition comprising a first composition, wherein the first composition comprises at least one ethylene-based polymer and wherein the first composition comprises a MWCDI value greater than 0.9, and a melt index ratio (I10/I2) that meets the following equation: I10/I2≧7.0−1.2×log (I2).
These and other embodiments are described in more detail in the Detailed Description.
It has been discovered that the inventive compositions can be used to form inventive films with improved toughness. Such compositions contain an ethylene-based polymer that has a superior comonomer distribution, which is significantly higher in comonomer concentration, and a good distribution of comonomer, in the high molecular weight polymer molecules, and is significantly lower in comonomer concentration in the low molecular weight polymer molecules, as compared to conventional polymers of the art at the same overall density. It has also been discovered that the ethylene-based polymer has low LCB (Long Chain Branches), as indicated by low ZSVR, as compared to conventional polymers. As a result of this optimized distribution of the comonomer, as well as the inherent low LCB nature, the inventive compositions have more tie chains, and thus, improved film toughness. The inventive compositions can be useful in forming the inventive cast films of the present invention.
As discussed above, the invention provides a composition comprising a first composition, comprising at least one ethylene-based polymer, wherein the first composition comprises a MWCDI value greater than 0.9, and a melt index ratio (I10/I2) that meets the following equation: I10/I2≧7.0−1.2×log (I2).
The inventive composition may comprise a combination of two or more embodiments described herein.
The first composition may comprise a combination of two or more embodiments as described herein.
The ethylene-based polymer may comprise a combination of two or more embodiments as described herein.
In one embodiment, the first composition has a MWCDI value less than, or equal to, 10.0, further less than, or equal to, 8.0, further less than, or equal to, 6.0.
In one embodiment, the first composition has a MWCDI value less than, or equal to, 5.0, further less than, or equal to, 4.0, further less than, or equal to, 3.0.
In one embodiment, the first composition has a MWCDI value greater than, or equal to, 1.0, further greater than, or equal to, 1.1, further greater than, or equal to, 1.2.
In one embodiment, the first composition has a MWCDI value greater than, or equal to, 1.3, further greater than, or equal to, 1.4, further greater than, or equal to, 1.5.
In one embodiment, the first composition has a melt index ratio I10/I2 greater than, or equal to, 7.0, further greater than, or equal to, 7.1, further greater than, or equal to, 7.2, further greater than, or equal to, 7.3.
In one embodiment, the first composition has a melt index ratio I10/I2 less than, or equal to, 9.2, further less than, or equal to, 9.0, further less than, or equal to, 8.8, further less than, or equal to, 8.5.
In one embodiment, the first composition has a ZSVR value from 1.2 to 3.0, further from 1.2 to 2.5, further 1.2 to 2.0.
In one embodiment, the first composition has a vinyl unsaturation level greater than 10 vinyls per 1,000,000 total carbons. For example, greater than 20 vinyls per 1,000,000 total carbons, or greater than 50 vinyls per 1,000,000 total carbons, or greater than 70 vinyls per 1,000,000 total carbons, or greater than 100 vinyls per 1,000,000 total carbons.
In one embodiment, the first composition has a density in the range of 0.910 to 0.940 g/cm3, for example from 0.910 to 0.930, or from 0.910 to 0.925 g/cm3. For example, the density can be from a lower limit of 0.910, 0.912, or 0.914 g/cm3, to an upper limit of 0.925, 0.927, or 0.930 g/cm3 (1 cm3=1 cc).
In one embodiment, the first composition has a melt index (I2 or I2; at 190° C./2.16 kg) from 0.1 to 50 g/10 minutes, for example from 0.1 to 30 g/10 minutes, or from 0.1 to 20 g/10 minutes, or from 0.1 to 10 g/10 minutes. For example, the melt index (I2 or I2; at 190° C./2.16 kg) can be from a lower limit of 0.1, 0.2, or 0.5 g/10 minutes, to an upper limit of 1.0, 2.0, 3.0, 4.0, 5.0, 10, 15, 20, 25, 30, 40, or 50 g/10 minutes.
In one embodiment, the first composition has a molecular weight distribution, expressed as the ratio of the weight average molecular weight to number average molecular weight (Mw/Mn; as determined by cony. GPC) in the range of from 2.2 to 5.0. For example, the molecular weight distribution (Mw/Mn) can be from a lower limit of 2.2, 2.3, 2.4, 2.5, 3.0, 3.2, or 3.4, to an upper limit of 3.9, 4.0, 4.1, 4.2, 4.5, 5.0.
In one embodiment, the first composition has a number average molecular weight (Mn; as determined by cony. GPC) in the range from 10,000 to 50,000 g/mole. For example, the number average molecular weight can be from a lower limit of 10,000, 20,000, or 25,000 g/mole, to an upper limit of 35,000, 40,000, 45,000, or 50,000 g/mole.
In one embodiment, the first composition has a weight average molecular weight (Mw; as determined by cony. GPC) in the range from 70,000 to 200,000 g/mole. For example, the number average molecular weight can be from a lower limit of 70,000, 75,000, or 78,000 g/mole, to an upper limit of 120,000, 140,000, 160,000, 180,000 or 200,000 g/mole.
In one embodiment, the first composition has a melt viscosity ratio, Eta*0.1/Eta*100, in the range from 2.2 to 7.0. For example, the number average molecular weight can be from a lower limit of 2.2, 2.3, 2.4 or 2.5, to an upper limit of 6.0, 6.2, 6.5, or 7.0.
In one embodiment, the ethylene-based polymer is an ethylene/α-olefin interpolymer, and further an ethylene/α-olefin copolymer.
In one embodiment, the first ethylene-based polymer is an ethylene/α-olefin interpolymer, and further an ethylene/α-olefin copolymer.
In one embodiment, the α-olefin has less than, or equal to, 20 carbon atoms. For example, the α-olefin comonomers may preferably have 3 to 10 carbon atoms, and more preferably 3 to 8 carbon atoms. Exemplary α-olefin comonomers include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 4-methyl-1-pentene. The one or more α-olefin comonomers may, for example, be selected from the group consisting of propylene, 1-butene, 1-hexene, and 1-octene; or in the alternative, from the group consisting of 1-butene, 1-hexene and 1-octene, and further 1-hexene and 1-octene.
In one embodiment, the ethylene-based polymer, or first ethylene-based polymer, has a molecular weight distribution (Mw/Mn; as determined by cony. GPC) in the range from 1.5 to 4.0, for example, from 1.5 to 3.5, or from 2.0 to 3.0. For example, the molecular weight distribution (Mw/Mn) can be from a lower limit of 1.5, 1.7, 2.0, 2.1, or 2.2, to an upper limit of 2.5, 2.6, 2.8, 3.0, 3.5, or 4.0.
In one embodiment, the first composition further comprises a second ethylene-based polymer. In a further embodiment, the second ethylene-based polymer is an ethylene/α-olefin interpolymer, and further an ethylene/α-olefin copolymer, or a LDPE.
In one embodiment, the α-olefin has less than, or equal to, 20 carbon atoms. For example, the α-olefin comonomers may preferably have 3 to 10 carbon atoms, and more preferably 3 to 8 carbon atoms. Exemplary α-olefin comonomers include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 4-methyl-1-pentene. The one or more α-olefin comonomers may, for example, be selected from the group consisting of propylene, 1-butene, 1-hexene, and 1-octene; or in the alternative, from the group consisting of 1-butene, 1-hexene and 1-octene, and further 1-hexene and 1-octene.
In one embodiment, the second ethylene-based polymer is a heterogeneously branched ethylene/α-olefin interpolymer, and further a heterogeneously branched ethylene/α-olefin copolymer. Heterogeneously branched ethylene/α-olefin interpolymers and copolymers are typically produced using Ziegler/Natta type catalyst system, and have more comonomer distributed in the lower molecular weight molecules of the polymer.
In one embodiment, the second ethylene-based polymer has a molecular weight distribution (Mw/Mn) in the range from 3.0 to 5.0, for example from 3.2 to 4.6. For example, the molecular weight distribution (Mw/Mn) can be from a lower limit of 3.2, 3.3, 3.5, 3.7, or 3.9, to an upper limit of 4.6, 4.7, 4.8, 4.9, or 5.0.
In one embodiment, the composition comprises from 50 to 80 wt %, or from 50 to 85 wt %, or from 50 to 90 wt %, or from 50 to 95 wt % of the first composition, based on the weight of the composition.
In one embodiment, the composition comprises greater than or equal to 80 wt %, or greater than or equal to 85 wt %, or greater than or equal to 90 wt %, or greater than or equal to 95 wt %, or greater than or equal to 98 wt % of the first composition, based on the weight of the composition.
In one embodiment, the composition further comprises another polymer. In a further embodiment, the polymer is selected from the following: a LLDPE, a VLDPE (a very low density polyethylene), a MDPE, a LDPE, a HDPE, a HMWHDPE (a high molecular weight HDPE), a propylene-based polymer, a polyolefin plastomer, a polyolefin elastomer, an olefin block copolymer, an ethylene vinyl acetate, an ethylene acrylic acid, an ethylene methacrylic acid, an ethylene methyl acrylate, an ethylene ethyl acrylate, an ethylene butyl acrylate, a polyisobutylene, a maleic anhydride-grafted polyolefin, an ionomer of any of the foregoing, or a combination thereof.
In one embodiment, the composition further comprises a LDPE. In a further embodiment, the LDPE is present in an amount from 5 to 50 wt %, further from 10 to 40 wt %, further from 15 to 30 wt %, based on the weight of the composition. In a further embodiment, the LDPE has a density from 0.915 to 0.930 g/cc, and a melt index (12) from 0.15 to 30 g/10 min, further from 0.25 to 20 g/10 min.
In one embodiment, the composition further comprises one or more additives.
The invention also provides an article comprising at least one component formed from an inventive composition as described herein. In a further embodiment, the article is a film or a coating.
In some embodiments, the present invention relates to a cast film formed from any of the inventive compositions as described herein. In some embodiments, the cast film is a monolayer film. The cast film, in some embodiments, is a multilayer film. In some embodiments, the cast film comprises up to 35 layers.
In some embodiments, a cast film of the present invention has a thickness of up to 30 mils. For example, the cast film can have a thickness from a lower limit of 0.2 mils, 0.3 mils, 0.5 mils, 1.0 mil, 1.75 mils, or 2.0 mils to an upper limit of 10 mils, 15 mils, 20 mils, 25 mils, or 30 mils.
A cast film of the present invention, in some embodiments, comprises at least 20 percent by weight of the inventive composition, preferably at least 30 percent by weight of the inventive composition, and more preferably at least 40 percent by weight of the inventive composition.
In some embodiments where the cast film is a multilayer film, the film can further comprise a second layer, wherein the second layer comprises a polymer selected from the following: the inventive composition, a LLDPE, a VLDPE (a very low density polyethylene), a MDPE, a LDPE, a HDPE, a HMWHDPE (a high molecular weight HDPE), a propylene-based polymer, a polyolefin plastomer, a polyolefin elastomer, an olefin block copolymer, an ethylene vinyl acetate, an ethylene acrylic acid, an ethylene methacrylic acid, an ethylene methyl acrylate, an ethylene ethyl acrylate, an ethylene butyl acrylate, an isobutylene, a maleic anhydride-grafted polyolefin, an ionomer of any of the foregoing, or a combination thereof. The cast film, in some embodiments, can comprise a third layer, wherein the third layer comprises a polymer selected from the following: the first composition, a LLDPE, a VLDPE, a LDPE, a MDPE, a HDPE, a HMWHDPE, a propylene-based polymer, a polyolefin plastomer, a polyolefin elastomer, an olefin block copolymer, an ethylene vinyl acetate, an ethylene acrylic acid, an ethylene methacrylic acid, an ethylene methyl acrylate, an ethylene ethyl acrylate, an ethylene butyl acrylate, an isobutylene, a maleic anhydride-grafted polyolefin, an ionomer of any of the foregoing, or a combination thereof.
A multilayer cast film can comprise up to 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11 layers in various embodiments.
In some embodiments, the inventive composition used in the layer of cast film has a density in the range of 0.885 to 0.945 g/cm3, for example from 0.895 to 0.940, or from 0.905 to 0.935 g/cm3, or from 0.910 to 0.928 g/cm3. For example, the density can be from a lower limit of 0.885, 0.895, 0.905, or 0.910 g/cm3, to an upper limit of 0.928, 0.935, 0.940, or 0.945 g/cm3 (1 cm3=1 cc).
In one embodiment, the inventive composition used in the layer of cast film has a melt index (I2 or I2; at 190° C./2.16 kg) from 0.5 to 30 g/10 minutes, for example from 1 to 15 g/10 minutes, or from 2 to 10 g/10 minutes. For example, the melt index (I2 or I2; at 190° C./2.16 kg) can be from a lower limit of 0.5, 1, or 2 g/10 minutes, to an upper limit of 10, 15, or 30 g/10 minutes. In some embodiments, the cast film can be stretched up to 300% elongation in machine direction.
In some embodiments, the cast film comprising a layer formed from the inventive composition can be laminated to another film or a woven structure.
In some embodiments, a cast film of the present invention can comprise coextruded multilayer films comprising a core component that is a nanolayer structure. In such embodiments, the core component can be a layer comprising any of the inventive compositions disclosed herein. In some embodiments, the core component comprises 15 to 4,000 layers (sublayers). Each layer (sublayer) can have a thickness of 10 nanometers to 10 microns in some embodiments. In some embodiments, the layers (sublayers) in the core component comprise two or more types of films.
Cast films of the present invention can be incorporated into a variety of articles including, for example, food packages, industrial and consumer packaging materials, foamed films, and others.
Food packages can comprise a cast film according to the present invention. A variety of food items known to those of skill in the art can be provided in such food packages including, for example, solid foods, liquids, beverages, cooking ingredients (e.g., sugar, flour, etc.), etc. Exemplary food packaging materials include films for packaging baked goods, candy wrap, cheese, and others.
Industrial and consumer packaging materials can comprise a cast film according to the present invention. Exemplary industrial and consumer packaging materials include stretch wrap, silage wrap, protective films, and others. In embodiments related to silage wraps, in some embodiments, the silage wrap can further comprise polyisobutylene.
Polymerization processes include, but are not limited to, solution polymerization processes, using one or more conventional reactors, e.g., loop reactors, isothermal reactors, adiabatic reactors, stirred tank reactors, autoclave reactors in parallel, series, and/or any combinations thereof. The ethylene based polymer compositions may, for example, be produced via solution phase polymerization processes, using one or more loop reactors, adiabatic reactors, and combinations thereof.
In general, the solution phase polymerization process occurs in one or more well mixed reactors, such as one or more loop reactors and/or one or more adiabatic reactors at a temperature in the range from 115 to 250° C.; for example, from 135 to 200° C., and at pressures in the range of from 300 to 1000 psig, for example, from 450 to 750 psig.
In one embodiment, the ethylene based polymer composition (e.g., the first composition of claim 1) may be produced in two loop reactors in series configuration, the first reactor temperature is in the range from 115 to 200° C., for example, from 135 to 165° C., and the second reactor temperature is in the range from 150 to 210° C., for example, from 185 to 200° C. In another embodiment, the ethylene based polymer composition may be produced in a single reactor, the reactor temperature is in the range from 115 to 200° C., for example from 130 to 190° C. The residence time in a solution phase polymerization process is typically in the range from 2 to 40 minutes, for example from 5 to 20 minutes. Ethylene, solvent, one or more catalyst systems, optionally one or more cocatalysts, and optionally one or more comonomers, are fed continuously to one or more reactors. Exemplary solvents include, but are not limited to, isoparaffins. For example, such solvents are commercially available under the name ISOPAR E from ExxonMobil Chemical. The resultant mixture of the ethylene based polymer composition and solvent is then removed from the reactor or reactors, and the ethylene based polymer composition is isolated. Solvent is typically recovered via a solvent recovery unit, i.e., heat exchangers and separator vessel, and the solvent is then recycled back into the polymerization system.
In one embodiment, the ethylene based polymer composition may be produced, via a solution polymerization process, in a dual reactor system, for example a dual loop reactor system, wherein ethylene, and optionally one or more α-olefins, are polymerized in the presence of one or more catalyst systems, in one reactor, to produce a first ethylene-based polymer, and ethylene, and optionally one or more α-olefins, are polymerized in the presence of one or more catalyst systems, in a second reactor, to produce a second ethylene-based polymer. Additionally, one or more cocatalysts may be present.
In another embodiment, the ethylene based polymer composition may be produced via a solution polymerization process, in a single reactor system, for example, a single loop reactor system, wherein ethylene, and optionally one or more α-olefins, are polymerized in the presence of one or more catalyst systems. Additionally, one or more cocatalysts may be present.
As discussed above, the invention provides a process to form a composition comprising at least two ethylene-based polymers, said process comprising the following:
polymerizing ethylene, and optionally at least one comonomer, in solution, in the present of a catalyst system comprising a metal-ligand complex of Structure I, to form a first ethylene-based polymer; and
polymerizing ethylene, and optionally at least one comonomer, in the presence of a catalyst system comprising a Ziegler/Natta catalyst, to form a second ethylene-based polymer; and wherein Structure I is as follows:
wherein:
M is titanium, zirconium, or hafnium, each, independently, being in a formal oxidation state of +2, +3, or +4; and
n is an integer from 0 to 3, and wherein when n is 0, X is absent; and
each X, independently, is a monodentate ligand that is neutral, monoanionic, or dianionic; or two Xs are taken together to form a bidentate ligand that is neutral, monoanionic, or dianionic; and
X and n are chosen, in such a way, that the metal-ligand complex of formula (I) is, overall, neutral; and
each Z, independently, is O, S, N(C1-C40)hydrocarbyl, or P(C1-C40)hydrocarbyl; and wherein the Z-L-Z fragment is comprised of formula (1):
R1 through R16 are each, independently, selected from the group consisting of the following: a substituted or unsubstituted (C1-C40)hydrocarbyl, a substituted or unsubstituted (C1-C40)heterohydrocarbyl, Si(RC)3, Ge(RC)3, P(RP)2, N(RN)2, ORC, SRC, NO2, CN, CF3, RCS(O)—, RCS(O)2—, (RC)2C═N—, RCC(O)O—, RCOC(O)—, RCC(O)N(R)—, (RC)2NC(O)—, halogen atom, hydrogen atom; and wherein each RC is independently a (C1-C30)hydrocarbyl; RP is a (C1-C30)hydrocarbyl; and RN is a (C1-C30)hydrocarbyl; and
wherein, optionally, two or more R groups (from R1 through R16) can combine together into one or more ring structures, with such ring structures each, independently, having from 3 to 50 atoms in the ring, excluding any hydrogen atom.
An inventive process may comprise a combination of two or more embodiments as described herein.
In one embodiment, said process comprises polymerizing ethylene, and optionally at least one α-olefin, in solution, in the presence of a catalyst system comprising a metal-ligand complex of Structure I, to form a first ethylene-based polymer; and polymerizing ethylene, and optionally at least one α-olefin, in the presence of a catalyst system comprising a Ziegler/Natta catalyst, to form a second ethylene-based polymer. In a further embodiment, each α-olefin is independently a C1-C8 α-olefin.
In one embodiment, optionally, two or more R groups from R9 through R13, or R4 through R8 can combine together into one or more ring structures, with such ring structures each, independently, having from 3 to 50 atoms in the ring, excluding any hydrogen atom.
In one embodiment, M is hafnium.
In one embodiment, R3 and R14 are each independently an alkyl, and further a C1-C3 alkyl, and further methyl.
In one embodiment, R1 and R16 are each as follows:
In one embodiment, each of the aryl, heteroaryl, hydrocarbyl, heterohydrocarbyl, Si(RC)3, Ge(RC)3, P(RP)2, N(RN)2, ORC, SRC, RCS(O)—, RCS(O)2—, (RC)2C═N—, RCC(O)O—, RCOC(O)—, RCC(O)N(R)—, (RC)2NC(O)—, hydrocarbylene, and heterohydrocarbylene groups, independently, is unsubstituted or substituted with one or more RS substituents; and each RS independently is a halogen atom, polyfluoro substitution, perfluoro substitution, unsubstituted (C1-C18)alkyl, F3C—, FCH2O—, F2HCO—, F3CO—, R3Si—, R3Ge—, RO—, RS—, RS(O)—, RS(O)2—, R2P—, R2N—, R2C═N—, NC—, RC(O)O—, ROC(O)—, RC(O)N(R)—, or R2NC(O)—, or two of the RS are taken together to form an unsubstituted (C1-C18)alkylene, wherein each R independently is an unsubstituted (C1-C18)alkyl.
In one embodiment, two or more of R1 through R16 do not combine to form one or more ring structures.
In one embodiment, the catalyst system suitable for producing the first ethylene/α-olefin interpolymer is a catalyst system comprising bis((2-oxoyl-3-(dibenzo-1H-pyrrole-1-yl)-5-(methyl)phenyl)-2-phenoxymethyl)-methylene-1,2-cyclohexanediylhafnium (IV) dimethyl, represented by the following Structure: IA:
The Ziegler/Natta catalysts suitable for use in the invention are typical supported, Ziegler-type catalysts, which are particularly useful at the high polymerization temperatures of the solution process. Examples of such compositions are those derived from organomagnesium compounds, alkyl halides or aluminum halides or hydrogen chloride, and a transition metal compound. Examples of such catalysts are described in U.S. Pat. Nos. 4,612,300; 4,314,912; and 4,547,475; the teachings of which are incorporated herein by reference.
Particularly suitable organomagnesium compounds include, for example, hydrocarbon soluble dihydrocarbylmagnesium, such as the magnesium dialkyls and the magnesium diaryls. Exemplary suitable magnesium dialkyls include, particularly, n-butyl-sec-butylmagnesium, diisopropylmagnesium, di-n-hexylmagnesium, isopropyl-n-butyl-magnesium, ethyl-n-hexyl-magnesium, ethyl-n-butylmagnesium, di-n-octylmagnesium, and others, wherein the alkyl has from 1 to 20 carbon atoms. Exemplary suitable magnesium diaryls include diphenylmagnesium, dibenzylmagnesium and ditolylmagnesium. Suitable organomagnesium compounds include alkyl and aryl magnesium alkoxides and aryloxides and aryl and alkyl magnesium halides, with the halogen-free organomagnesium compounds being more desirable.
Halide sources include active non-metallic halides, metallic halides, and hydrogen chloride. Suitable non-metallic halides are represented by the formula R′X, wherein R′ is hydrogen or an active monovalent organic radical, and X is a halogen. Particularly suitable non-metallic halides include, for example, hydrogen halides and active organic halides, such as t-alkyl halides, allyl halides, benzyl halides and other active hydrocarbyl halides. By an active organic halide is meant a hydrocarbyl halide that contains a labile halogen at least as active, i.e., as easily lost to another compound, as the halogen of sec-butyl chloride, preferably as active as t-butyl chloride. In addition to the organic monohalides, it is understood that organic dihalides, trihalides and other polyhalides that are active, as defined hereinbefore, are also suitably employed. Examples of preferred active non-metallic halides, include hydrogen chloride, hydrogen bromide, t-butyl chloride, t-amyl bromide, allyl chloride, benzyl chloride, crotyl chloride, methylvinyl carbinyl chloride, a-phenylethyl bromide, diphenyl methyl chloride, and the like. Most preferred are hydrogen chloride, t-butyl chloride, allyl chloride and benzyl chloride.
Suitable metallic halides include those represented by the formula MRy-a Xa, wherein: M is a metal of Groups IIB, IIIA or IVA of Mendeleev's periodic Table of Elements; R is a monovalent organic radical; X is a halogen; y has a value corresponding to the valence of M; and “a” has a value from 1 to y. Preferred metallic halides are aluminum halides of the formula AlR3-a Xa, wherein each R is independently hydrocarbyl, such as alkyl; X is a halogen; and a is a number from 1 to 3. Most preferred are alkylaluminum halides, such as ethylaluminum sesquichloride, diethylaluminum chloride, ethylaluminum dichloride, and diethylaluminum bromide, with ethylaluminum dichloride being especially preferred. Alternatively, a metal halide, such as aluminum trichloride, or a combination of aluminum trichloride with an alkyl aluminum halide, or a trialkyl aluminum compound may be suitably employed.
Any of the conventional Ziegler-Natta transition metal compounds can be usefully employed, as the transition metal component in preparing the supported catalyst component. Typically, the transition metal component is a compound of a Group IVB, VB, or VIB metal. The transition metal component is generally, represented by the formulas: TrX′4-q (OR1)q, TrX′4-q (R2)q, VOX′3 and VO(OR)3.
Tr is a Group IVB, VB, or VIB metal, preferably a Group IVB or VB metal, preferably titanium, vanadium or zirconium; q is 0 or a number equal to, or less than, 4; X′ is a halogen, and R1 is an alkyl group, aryl group or cycloalkyl group having from 1 to 20 carbon atoms; and R2 is an alkyl group, aryl group, aralkyl group, substituted aralkyls, and the like.
The aryl, aralkyls and substituted aralkys contain 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms. When the transition metal compound contains a hydrocarbyl group, R2, being an alkyl, cycloalkyl, aryl, or aralkyl group, the hydrocarbyl group will preferably not contain an H atom in the position beta to the metal carbon bond. Illustrative, but non-limiting, examples of aralkyl groups are methyl, neopentyl, 2,2-dimethylbutyl, 2,2-dimethylhexyl; aryl groups such as benzyl; cycloalkyl groups such as 1-norbornyl. Mixtures of these transition metal compounds can be employed if desired.
Illustrative examples of the transition metal compounds include TiCl4, TiBr4, Ti(OC2H5)3C1, Ti(OC2H5)Cl3, Ti(OC4H9)3Cl, Ti(OC3H7)2Cl2, Ti(OC6H13)2Cl2, Ti(OC8H17)2Br2, and Ti(OC12H25)Cl3, Ti(O-iC3H7)4, and Ti(O-nC4H9)4. Illustrative examples of vanadium compounds include VCl4, VOCl3, VO(OC2H5)3, and VO(OC4H9)3. Illustrative examples of zirconium compounds include ZrCl4, ZrCl3(OC2H5), ZrCl2(OC2H5)2, ZrCl(OC2H5)3, Zr(OC2H5)4, ZrCl3(OC4H9), ZrCl2(OC4H9)2, and ZrCl(OC4H9)3.
An inorganic oxide support may be used in the preparation of the catalyst, and the support may be any particulate oxide, or mixed oxide which has been thermally or chemically dehydrated, such that it is substantially free of adsorbed moisture. See U.S. Pat. Nos. 4,612,300; 4,314,912; and 4,547,475; the teachings of which are incorporated herein by reference.
In one embodiment, the composition comprises a MWCDI value greater than 0.9.
In one embodiment, the composition comprises a melt index ratio (I10/I2) that meets the following equation: I10/I2≧7.0−1.2×log (I2).
The composition may comprise one embodiment, or a combination of two or more embodiments, as listed above for the “first composition.”
An inventive process may comprise a combination of two or more embodiments described herein.
The above described catalyst systems can be rendered catalytically active by contacting it to, or combining it with, the activating co-catalyst, or by using an activating technique, such as those known in the art, for use with metal-based olefin polymerization reactions. Suitable activating co-catalysts, for use herein, include alkyl aluminums; polymeric or oligomeric alumoxanes (also known as aluminoxanes); neutral Lewis acids; and non-polymeric, non-coordinating, ion-forming compounds (including the use of such compounds under oxidizing conditions). A suitable activating technique is bulk electrolysis. Combinations of one or more of the foregoing activating co-catalysts and techniques are also contemplated. The term “alkyl aluminum” means a monoalkyl aluminum dihydride or monoalkylaluminum dihalide, a dialkyl aluminum hydride or dialkyl aluminum halide, or a trialkylaluminum. Aluminoxanes and their preparations are known at, for example, U.S. Pat. No. 6,103,657. Examples of preferred polymeric or oligomeric alumoxanes are methylalumoxane, triisobutylaluminum-modified methylalumoxane, and isobutylalumoxane.
Exemplary Lewis acid activating co-catalysts are Group 13 metal compounds containing from 1 to 3 hydrocarbyl substituents as described herein. In some embodiments, exemplary Group 13 metal compounds are tri(hydrocarbyl)-substituted-aluminum or tri(hydrocarbyl)-boron compounds. In some other embodiments, exemplary Group 13 metal compounds are tri(hydrocarbyl)-substituted-aluminum or tri(hydrocarbyl)-boron compounds are tri((C1-C10)alkyl)aluminum or tri((C6-C18)aryl)boron compounds and halogenated (including perhalogenated) derivatives thereof. In some other embodiments, exemplary Group 13 metal compounds are tris(fluoro-substituted phenyl)boranes, in other embodiments, tris(pentafluorophenyl)borane. In some embodiments, the activating co-catalyst is a tris((C1-C20)hydrocarbyl) borate (e.g., trityl tetrafluoroborate) or a tri((C1-C20)hydrocarbyl)ammonium tetra((C1-C20)hydrocarbyl)borane (e.g., bis(octadecyl)methylammonium tetrakis(pentafluorophenyl)borane). As used herein, the term “ammonium” means a nitrogen cation that is a ((C1-C20)hydrocarbyl)4N+, a ((C1-C20)hydrocarbyl)3N(H)+, a ((C1-C20)hydrocarbyl)2N(H)2+, (C1-C20)hydrocarbylN(H)3+, or N(H)4+, wherein each (C1-C20)hydrocarbyl may be the same or different.
Exemplary combinations of neutral Lewis acid activating co-catalysts include mixtures comprising a combination of a tri((C1-C4)alkyl)aluminum and a halogenated tri((C6-C18)aryl)boron compound, especially a tris(pentafluorophenyl)borane. Other exemplary embodiments are combinations of such neutral Lewis acid mixtures with a polymeric or oligomeric alumoxane, and combinations of a single neutral Lewis acid, especially tris(pentafluorophenyl)borane with a polymeric or oligomeric alumoxane. Exemplary embodiments ratios of numbers of moles of (metal-ligand complex):(tris(pentafluoro-phenylborane): (alumoxane) [e.g., (Group 4 metal-ligand complex):(tris(pentafluoro-phenylborane):(alumoxane)] are from 1:1:1 to 1:10:30, other exemplary embodiments are from 1:1:1.5 to 1:5:10.
Many activating co-catalysts and activating techniques have been previously taught, with respect to different metal-ligand complexes, in the following U.S. patents: U.S. Pat. No. 5,064,802; U.S. Pat. No. 5,153,157; U.S. Pat. No. 5,296,433; U.S. Pat. No. 5,321,106; U.S. Pat. No. 5,350,723; U.S. Pat. No. 5,425,872; U.S. Pat. No. 5,625,087; U.S. Pat. No. 5,721,185; U.S. Pat. No. 5,783,512; U.S. Pat. No. 5,883,204; U.S. Pat. No. 5,919,983; U.S. Pat. No. 6,696,379; and U.S. Pat. No. 7,163,907. Examples of suitable hydrocarbyloxides are disclosed in U.S. Pat. No. 5,296,433. Examples of suitable Bronsted acid salts for addition polymerization catalysts are disclosed in U.S. Pat. No. 5,064,802; U.S. Pat. No. 5,919,983; U.S. Pat. No. 5,783,512. Examples of suitable salts of a cationic oxidizing agent and a non-coordinating, compatible anion, as activating co-catalysts for addition polymerization catalysts, are disclosed in U.S. Pat. No. 5,321,106. Examples of suitable carbenium salts as activating co-catalysts for addition polymerization catalysts are disclosed in U.S. Pat. No. 5,350,723. Examples of suitable silylium salts, as activating co-catalysts for addition polymerization catalysts, are disclosed in U.S. Pat. No. 5,625,087. Examples of suitable complexes of alcohols, mercaptans, silanols, and oximes with tris(pentafluorophenyl)borane are disclosed in U.S. Pat. No. 5,296,433. Some of these catalysts are also described in a portion of U.S. Pat. No. 6,515,155 B1, beginning at column 50, at line 39, and going through column 56, at line 55, only the portion of which is incorporated by reference herein.
In some embodiments, the above described catalyst systems can be activated to form an active catalyst composition by combination with one or more cocatalyst, such as a cation forming cocatalyst, a strong Lewis acid, or a combination thereof. Suitable cocatalysts for use include polymeric or oligomeric aluminoxanes, especially methyl aluminoxane, as well as inert, compatible, noncoordinating, ion forming compounds. Exemplary suitable cocatalysts include, but are not limited to, modified methyl aluminoxane (MMAO), bis(hydrogenated tallow alkyl)methyl, tetrakis(pentafluorophenyl)borate(1-) amine, triethyl aluminum (TEA), and any combinations thereof.
In some embodiments, one or more of the foregoing activating co-catalysts are used in combination with each other. In one embodiment, a combination of a mixture of a tri((C1-C4)hydrocarbyl)aluminum, tri((C1-C4)hydrocarbyl)borane, or an ammonium borate with an oligomeric or polymeric alumoxane compound, can be used.
An inventive composition may comprise one or more additives. Additives include, but are not limited to, antistatic agents, color enhancers, dyes, lubricants, fillers (for example, TiO2 or CaCO3), opacifiers, nucleators, processing aids, pigments, primary anti-oxidants, secondary anti-oxidants, UV stabilizers, anti-blocks, slip agents, tackifiers, fire retardants, anti-microbial agents, odor reducer agents, anti-fungal agents, and combinations thereof. An inventive composition may comprise from about 0.001 to about 10 percent by the combined weight of such additives, based on the weight of the composition including such additives. In some embodiments, such as applications where fire resistance is important, the combined weight of such additives can be up to 40 weight percent.
An inventive composition may further comprise one or more other polymers. For example one or more other ethylene-based polymers (such polymers differ in one or more properties from the ethylene-based polymer of the first composition and the second ethylene-based polymer; i.e., density, melt index, comonomer, Mn, Mw, and/or MWD), or one or more propylene-based polymers, or combinations thereof. Such compositions may be blended via any method, known to a person of ordinary skill in the art, including, but not limited to, dry blending, and melt blending via any suitable equipment, for example, an extruder.
The invention provides for an article comprising at least one component formed from an inventive composition. Articles includes, but are not limited to, film, sheets, coatings, and multilayer structures. Multilayer structures typically comprise one or more film layers or sheets comprising an inventive composition. The multilayer structure may further comprise one or more layers comprising one or more polyamides, one or more polyesters, one or more olefin-based polymers, and combinations thereof.
In one embodiment, the inventive compositions according to the present invention are characterized by one or more of the followings: (a) having a Dart impact A of at least 400 g, measured according to ASTM D1709 (Method A), when said composition is formed into a monolayer blown film having a thickness of 1 mil; and/or (b) having a normalized machine direction Elmendorf tear of at least 250 g/mil, measured according to ASTM D1922, when said polyolefin composition is formed into a monolayer blown film having a thickness of 1 mil.
In one embodiment, an inventive composition further comprises from 5 to 20 percent by weight of low density polyethylene (LDPE). In a further embodiment, the composition has a Dart Impact A greater than 275 g, preferably greater than 300 g, measured according to ASTM D1709, when said composition is formed into a monolayer blown film having a thickness of 1 mil.
In some embodiments, the present invention relates to a cast film formed from any of the inventive compositions as described herein. In some embodiments, the cast film is a monolayer film. The cast film, in some embodiments, is a multilayer film. Cast films can be formed from inventive compositions using methods and equipment well-known to those of skill in the art.
The amount of the inventive composition to use in cast films of the present invention can depend on a number of factors including, for example, whether the film is a monolayer or multilayer film, the other layers in the film if it is a multilayer film, the desired properties of the film, the end use application of the film, the desired properties of the film, the equipment available to manufacture the film, and others. A cast film of the present invention, in some embodiments, comprises at least 20 percent by weight of the inventive composition, preferably at least 30 percent by weight of the inventive composition, and more preferably at least 40 percent by weight of the inventive composition.
Cast films of the present invention can have a variety of thicknesses. The thickness of the cast film can depend on a number of factors including, for example, whether the film is a monolayer or multilayer film, the other layers in the film if it is a multilayer film, the desired properties of the film, the end use application of the film, the desired properties of the film, the equipment available to manufacture the film, and others. In some embodiments, a cast film of the present invention has a thickness of up to 30 mils. For example, the cast film can have a thickness from a lower limit of 0.2 mils, 0.3 mils, 0.5 mils, 1.0 mil, 1.75 mils, or 2.0 mils to an upper limit of 10 mils, 15 mils, 20 mils, 25 mils, or 30 mils.
In embodiments where the cast film comprises a multilayer film, the number of layers in the film can depend on a number of factors including, for example, the desired properties of the film, the desired thickness of the film, the content of the other layers of the film, whether any of the layers in the film are to be foamed, the end use application of the film, the equipment available to manufacture the film, and others. A multilayer cast film can comprise up to 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11 layers in various embodiments.
The inventive composition, in some embodiments, can be used in more than one layer of the film. Other layers within a multilayer film of the present invention can comprise, in various embodiments, a polymer selected from the following: the inventive composition, a LLDPE, a VLDPE (a very low density polyethylene), a MDPE, a LDPE, a HDPE, a HMWHDPE (a high molecular weight HDPE), a propylene-based polymer, a polyolefin plastomer, a polyolefin elastomer, an olefin block copolymer, an ethylene vinyl acetate, an ethylene acrylic acid, an ethylene methacrylic acid, an ethylene methyl acrylate, an ethylene ethyl acrylate, an ethylene butyl acrylate, an isobutylene, a maleic anhydride-grafted polyolefin, an ionomer of any of the foregoing, or a combination thereof. In some embodiments, a multilayer film of the present invention can comprise one or more tie layers known to those of skill in the art.
In some embodiments, in a cast film comprising a layer formed from the composition comprising the inventive composition, the layer can be a sealant layer and/or an abuse layer.
In some embodiments, the cast film comprising a layer formed from the inventive composition can be laminated to another film or a woven structure.
Cast films of the present invention, in some embodiments, can be corona treated and/or printed (e.g., reverse or surface printed) using techniques known to those of skill in the art.
The cast films of the present invention may be subjected to a post-quench orientation step where the film is stretched at a temperature below the melting point of any polyethylene used in the film. The degree of stretching could be from 1.1:1 to 5:1 in the machine direction or the cross (transverse) direction or both directions. The degree of stretching is the ratio of the original film thickness to that of the film thickness of the stretched portion of the film. So the portion of the film that originally was 100 micron after a 3:1 stretch ratio in one direction (for example, the machine direction) would be 33 micron. In some embodiments the post-quench stretching is less than 4.5:1, 4:1, or 3.5:1 in the machine direction, the cross direction or both directions. In some preferred embodiments, the stretching is done in only one direction (that is, monoaxial orientation). In such cases, it may be preferred that the orientation be only in the machine direction. In some embodiments where the cast films are to be oriented, the orientation can be performed in-line (i.e., just after extrusion), or off-line as part of a separate process or at a different location.
For example, the stretching can be conducted in the machine direction using a set of rolls and in the cross direction using a tenter frame, or using other methods which uniformly stretch the films. Alternatively, the films may be stretched by techniques which stretch the film in a non-uniform manner such that localized regions of the film remain unstretched. Such techniques include local stretching, interdigitized rollers or embossing techniques. It should be understood that with such localized stretching, the degree of stretching referred to above for some embodiments (that is from 1.1 to 3.5 to 1) refers to the stretch in the area which were subjected to the stretching and not the overall film.
Cast films of the present invention can be incorporated into a variety of articles including, for example, food packages, industrial and consumer packaging materials, foamed films, and others. Cast films of the present invention might be particularly useful in applications that require a film with high dart, puncture and/or tear resistance properties.
In some embodiments, cast films of the present invention can be used to form laminates by laminating the film to a substrate (e.g., paperboard, metallic films, and other substrates to which cast films can be laminated).
Food packages can comprise a cast film according to the present invention. A variety of food items known to those of skill in the art can be provided in such food packages including, for example, solid foods, liquids, beverages, cooking ingredients (e.g., sugar, flour, etc.), etc. Exemplary food packaging materials include films for packaging baked goods, candy wrap, cheese, and others.
Industrial and consumer packaging materials can comprise a cast film according to the present invention. Exemplary industrial and consumer packaging materials include stretch wrap, silage wraps, protective films, and others. In embodiments related to silage wraps, in some embodiments, the silage wrap can further comprise polyisobutylene.
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.
The term “composition,” as used herein, includes material(s) which comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition.
The term “comprising,” and derivatives thereof, is not intended to exclude the presence of any additional component, step or procedure, whether or not the same is disclosed herein. In order to avoid any doubt, all compositions claimed herein 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 “polymer,” as used herein, refers to a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The generic term polymer thus embraces the term homopolymer (employed to refer to polymers prepared from only one type of monomer, with the understanding that trace amounts of impurities can be incorporated into the polymer structure), and the term interpolymer as defined hereinafter. Trace amounts of impurities may be incorporated into and/or within the polymer.
The term “interpolymer,” as used herein, refers to a polymer prepared by the polymerization of at least two different types of monomers. The generic term interpolymer thus includes copolymers (employed to refer to polymers prepared from two different types of monomers), and polymers prepared from more than two different types of monomers.
The term, “olefin-based polymer,” as used herein, refers to a polymer that comprises, in polymerized form, a majority amount of olefin monomer, for example ethylene or propylene (based on the weight of the polymer), and optionally may comprise at least one polymerized comonomer.
The term, “ethylene-based polymer,” as used herein, refers to a polymer that comprises a majority amount of polymerized ethylene monomer (based on the total weight of the polymer), and optionally may comprise at least one polymerized comonomer.
The term, “ethylene/α-olefin interpolymer,” as used herein, refers to an interpolymer that comprises, in polymerized form, a majority amount of ethylene monomer (based on the weight of the interpolymer), and at least one α-olefin.
The term, “ethylene/α-olefin copolymer,” as used herein, refers to a copolymer that comprises, in polymerized form, a majority amount of ethylene monomer (based on the weight of the copolymer), and an α-olefin, as the only two monomer types.
The term “propylene-based polymer,” as used herein, refers to a polymer that comprises, in polymerized form, a majority amount of propylene monomer (based on the total weight of the polymer) and optionally may comprise at least one polymerized comonomer.
Melt indices I2 (or 12) and I10 (or I10) were measured in accordance to ASTM D-1238 (method B) at 190° C. and at 2.16 kg and 10 kg load, respectively. Their values are reported in g/10 min.
Samples for density measurement were prepared according to ASTM D4703. Measurements were made, according to ASTM D792, Method B, within one hour of sample pressing.
Each sample was compression-molded into “3 mm thick×25 mm diameter” circular plaque, at 177° C., for five minutes, under 10 MPa pressure, in air. The sample was then taken out of the press and placed on a counter top to cool.
Constant temperature, frequency sweep measurements were performed on an ARES strain controlled rheometer (TA Instruments), equipped with 25 mm parallel plates, under a nitrogen purge. For each measurement, the rheometer was thermally equilibrated, for at least 30 minutes, prior to zeroing the gap. The sample disk was placed on the plate, and allowed to melt for five minutes at 190° C. The plates were then closed to 2 mm, the sample trimmed, and then the test was started. The method had an additional five minute delay built in, to allow for temperature equilibrium. The experiments were performed at 190° C., over a frequency range from 0.1 to 100 rad/s, at five points per decade interval. The strain amplitude was constant at 10%. The stress response was analyzed in terms of amplitude and phase, from which the storage modulus (G′), loss modulus (G″), complex modulus (G*), dynamic viscosity (η* or Eta*), and tan δ (or tan delta) were calculated.
Conventional Gel Permeation Chromatography (Cony. GPC)
A GPC-IR high temperature chromatographic system from PolymerChar (Valencia, Spain), was equipped with a Precision Detectors (Amherst, Mass.), 2-angle laser light scattering detector Model 2040, an IR5 infra-red detector and a 4-capillary viscometer, both from PolymerChar. Data collection was performed using PolymerChar Instrument Control software and data collection interface. The system was equipped with an on-line, solvent degas device and pumping system from Agilent Technologies (Santa Clara, Calif.).
Injection temperature was controlled at 150 degrees Celsius. The columns used, were three, 10-micron “Mixed-B” columns from Polymer Laboratories (Shropshire, UK). The solvent used was 1,2,4-trichlorobenzene. The samples were prepared at a concentration of “0.1 grams of polymer in 50 milliliters of solvent.” The chromatographic solvent and the sample preparation solvent each contained “200 ppm of butylated hydroxytoluene (BHT).” Both solvent sources were nitrogen sparged. Ethylene-based polymer samples were stirred gently at 160 degrees Celsius for three hours. The injection volume was “200 microliters,’ and the flow rate was “1 milliliters/minute.” The GPC column set was calibrated by running 21 “narrow molecular weight distribution” polystyrene standards. The molecular weight (MW) of the standards ranges from 580 to 8,400,000 g/mole, and the standards were contained in six “cocktail” mixtures. Each standard mixture had at least a decade of separation between individual molecular weights. The standard mixtures were purchased from Polymer Laboratories. The polystyrene standards were prepared at “0.025 g in 50 mL of solvent” for molecular weights equal to, or greater than, 1,000,000 g/mole, and at “0.050 g in 50 mL of solvent” for molecular weights less than 1,000,000 g/mole.
The polystyrene standards were dissolved at 80° C., with gentle agitation, for 30 minutes. The narrow standards mixtures were run first, and in order of decreasing “highest molecular weight component,” to minimize degradation. The polystyrene standard peak molecular weights were converted to polyethylene molecular weight using Equation 1 (as described in Williams and Ward, J. Polym. Sci., Polym. Letters, 6, 621 (1968)):
Mpolyethylene=A×(Mpolystyrene)B (Eqn. 1),
where M is the molecular weight, A is equal to 0.4316 and B is equal to 1.0.
Number-average molecular weight (Mn(conv gpc)), weight average molecular weight (Mw-cony gpc), and z-average molecular weight (Mz(conv gpc)) were calculated according to Equations 2-4 below.
In Equations 2-4, the RV is column retention volume (linearly-spaced), collected at “1 point per second,” the IR is the baseline-subtracted IR detector signal, in Volts, from the IR5 measurement channel of the GPC instrument, and MPE is the polyethylene-equivalent MW determined from Equation 1. Data calculation were performed using “GPC One software (version 2.013H)” from PolymerChar.
Zero-shear viscosities were obtained via creep tests, which were conducted on an AR-G2 stress controlled rheometer (TA Instruments; New Castle, Del.), using “25-mm-diameter” parallel plates, at 190° C. The rheometer oven was set to test temperature for at least 30 minutes, prior to zeroing the fixtures. At the testing temperature, a compression molded sample disk was inserted between the plates, and allowed to come to equilibrium for five minutes. The upper plate was then lowered down to 50 μm (instrument setting) above the desired testing gap (1.5 mm). Any superfluous material was trimmed off, and the upper plate was lowered to the desired gap. Measurements were done under nitrogen purging, at a flow rate of 5 L/min. The default creep time was set for two hours. Each sample was compression-molded into a “2 mm thick×25 mm diameter” circular plaque, at 177° C., for five minutes, under 10 MPa pressure, in air. The sample was then taken out of the press and placed on a counter top to cool.
A constant low shear stress of 20 Pa was applied for all of the samples, to ensure that the steady state shear rate was low enough to be in the Newtonian region. The resulting steady state shear rates were in the range from 10−3 to 10−1 s−1 for the samples in this study. Steady state was determined by taking a linear regression for all the data, in the last 10% time window of the plot of “log (J(t)) vs. log(t),” where J(t) was creep compliance and t was creep time. If the slope of the linear regression was greater than 0.97, steady state was considered to be reached, then the creep test was stopped. In all cases in this study, the slope meets the criterion within one hour. The steady state shear rate was determined from the slope of the linear regression of all of the data points, in the last 10% time window of the plot of “c vs. t,” where c was strain. The zero-shear viscosity was determined from the ratio of the applied stress to the steady state shear rate.
In order to determine if the sample was degraded during the creep test, a small amplitude oscillatory shear test was conducted before, and after, the creep test, on the same specimen from 0.1 to 100 rad/s. The complex viscosity values of the two tests were compared. If the difference of the viscosity values, at 0.1 rad/s, was greater than 5%, the sample was considered to have degraded during the creep test, and the result was discarded.
Zero-Shear Viscosity Ratio (ZSVR) is defined as the ratio of the zero-shear viscosity (ZSV) of the branched polyethylene material to the ZSV of a linear polyethylene material (see ANTEC proceeding below) at the equivalent weight average molecular weight (Mw(conv gpc)), according to the following Equation 5:
The ZSV value was obtained from creep test, at 190° C., via the method described above. The Mw(conv gpc) value was determined by the conventional GPC method (Equation 3), as discussed above. The correlation between ZSV of linear polyethylene and its Mw(conv gpc) was established based on a series of linear polyethylene reference materials. A description for the ZSV-Mw relationship can be found in the ANTEC proceeding: Karjala et al., Detection of Low Levels of Long-chain Branching in Polyolefins, Annual Technical Conference-Society of Plastics Engineers (2008), 66th 887-891.
A stock solution (3.26 g) was added to “0.133 g of the polymer sample” in 10 mm NMR tube. The stock solution was a mixture of tetrachloroethane-d2 (TCE) and perchloroethylene (50:50, w:w) with 0.001M Cr3+. The solution in the tube was purged with N2, for 5 minutes, to reduce the amount of oxygen. The capped sample tube was left at room temperature, overnight, to swell the polymer sample. The sample was dissolved at 110° C. with periodic vortex mixing. The samples were free of the additives that may contribute to unsaturation, for example, slip agents such as erucamide. Each 1H NMR analysis was run with a 10 mm cryoprobe, at 120° C., on Bruker AVANCE 400 MHz spectrometer.
Two experiments were run to get the unsaturation: the control and the double presaturation experiments. For the control experiment, the data was processed with an exponential window function with LB=1 Hz, and the baseline was corrected from 7 to −2 ppm. The signal from residual 1H of TCE was set to 100, and the integral Itotal from −0.5 to 3 ppm was used as the signal from whole polymer in the control experiment. The “number of CH2 group, NCH2,” in the polymer was calculated as follows in Equation 1A:
NCH2=Itotal/2 (Eqn. 1A).
For the double presaturation experiment, the data was processed with an exponential window function with LB=1 Hz, and the baseline was corrected from about 6.6 to 4.5 ppm. The signal from residual 1H of TCE was set to 100, and the corresponding integrals for unsaturations (Ivinylene, Itrisubstituted, Ivinyl and Ivinylidene) were integrated. It is well known to use NMR spectroscopic methods for determining polyethylene unsaturation, for example, see Busico, V., et al., Macromolecules, 2005, 38, 6988. The number of unsaturation unit for vinylene, trisubstituted, vinyl and vinylidene were calculated as follows:
N
vinylene
=I
vinylene/2 (Eqn. 2A),
N
trisubstituted
=I
trisubstitute (Eqn. 3A),
N
vinyl
=I
vinyl/2 (Eqn. 4A),
N
vinylidene
=I
vinylidene/2 (Eqn. 5A).
The unsaturation units per 1,000 carbons, all polymer carbons including backbone carbons and branch carbons, were calculated as follows:
N
vinylene/1,000C=(Nvinylene/NCH2)*1,000 (Eqn. 6A),
N
trisubstituted/1,000C=(Ntrisubstituted/NCH2)*1,000 (Eqn. 7A),
N
vinyl/1,000C=(Nvinyl/NCH2)*1,000 (Eqn. 8A)
N
vinylidene/1,000C=(NvinylideneNCH2)*1,000 (Eqn. 9A),
The chemical shift reference was set at 6.0 ppm for the 1H signal from residual proton from TCE-d2. The control was run with ZG pulse, NS=4, DS=12, SWH=10,000 Hz, AQ=1.64 s, D1=14 s. The double presaturation experiment was run with a modified pulse sequence, with 01P=1.354 ppm, O2P=0.960 ppm, PL9=57 db, PL21=70 db, NS=100, DS=4, SWH=10,000 Hz, AQ=1.64 s, D1=1 s (where D1 is the presaturation time), D13=13 s. Only the vinyl levels were reported in Table 2 below.
Samples are prepared by adding approximately 3 g of a 50/50 mixture of tetra-chloroethane-d2/orthodichlorobenzene, containing 0.025 M Cr(AcAc)3, to a “0.25 g polymer sample” in a 10 mm NMR tube. Oxygen is removed from the sample by purging the tube headspace with nitrogen. The samples are then dissolved, and homogenized, by heating the tube and its contents to 150° C., using a heating block and heat gun. Each dissolved sample is visually inspected to ensure homogeneity.
All data are collected using a Bruker 400 MHz spectrometer. The data is acquired using a 6 second pulse repetition delay, 90-degree flip angles, and inverse gated decoupling with a sample temperature of 120° C. All measurements are made on non-spinning samples in locked mode. Samples are allowed to thermally equilibrate for 7 minutes prior to data acquisition. The 13C NMR chemical shifts were internally referenced to the EEE triad at 30.0 ppm.
C13 NMR Comonomer Content: It is well known to use NMR spectroscopic methods for determining polymer composition. ASTM D 5017-96; J. C. Randall et al., in “NMR and Macromolecules” ACS Symposium series 247; J. C. Randall, Ed., Am. Chem. Soc., Washington, D.C., 1984, Ch. 9; and J. C. Randall in “Polymer Sequence Determination”, Academic Press, New York (1977) provide general methods of polymer analysis by NMR spectroscopy.
A GPC-IR, high temperature chromatographic system from PolymerChar (Valencia, Spain) was equipped with a Precision Detectors' (Amherst, Mass.) 2-angle laser light scattering detector Model 2040, and an IR5 infra-red detector (GPC-IR) and a 4-capillary viscometer, both from PolymerChar. The “15-degree angle” of the light scattering detector was used for calculation purposes. Data collection was performed using PolymerChar Instrument Control software and data collection interface. The system was equipped with an on-line, solvent degas device and pumping system from Agilent Technologies (Santa Clara, Calif.).
Injection temperature was controlled at 150 degrees Celsius. The columns used, were four, 20-micron “Mixed-A” light scattering columns from Polymer Laboratories (Shropshire, UK). The solvent was 1,2,4-trichlorobenzene. The samples were prepared at a concentration of “0.1 grams of polymer in 50 milliliters of solvent.” The chromatographic solvent and the sample preparation solvent each contained “200 ppm of butylated hydroxytoluene (BHT).” Both solvent sources were nitrogen sparged. Ethylene-based polymer samples were stirred gently, at 160 degrees Celsius, for three hours. The injection volume was “200 microliters,” and the flow rate was “1 milliliters/minute.”
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 g/mole. These standards were arranged in six “cocktail” mixtures, with at least a decade of separation between individual molecular weights. The standards were purchased from Polymer Laboratories (Shropshire UK). 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 g/mole, and at “0.050 grams in 50 milliliters of solvent” for molecular weights less than 1,000,000 g/mole. The polystyrene standards were dissolved at 80 degrees Celsius, with gentle agitation, for 30 minutes. The narrow standards mixtures were run first, and in order of decreasing “highest molecular weight component,” to minimize degradation. The polystyrene standard peak molecular weights were converted to polyethylene molecular weights using Equation 1B (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)):
Mpolyethylene=A×(Mpolystyrene)B (Eqn. 1B),
where M is the molecular weight, A has a value of approximately 0.40 and B is equal to 1.0. The A value was adjusted between 0.385 and 0.425 (depending upon specific column-set efficiency), such that NBS 1475A (NIST) linear polyethylene weight-average molecular weight corresponded to 52,000 g/mole, as calculated by Equation 3B, below:
In Equations 2B and 3B, RV is column retention volume (linearly-spaced), collected at “1 point per second.” The IR is the baseline-subtracted IR detector signal, in Volts, from the measurement channel of the GPC instrument, and the MPE is the polyethylene-equivalent MW determined from Equation 1B. Data calculation were performed using “GPC One software (version 2.013H)” from PolymerChar.
A calibration for the IR5 detector ratios was performed using at least ten ethylene-based polymer standards (polyethylene homopolymer and ethylene/octene copolymers; narrow molecular weight distribution and homogeneous comonomer distribution) of known short chain branching (SCB) frequency (measured by the 13C NMR Method, as discussed above), ranging from homopolymer (0 SCB/1000 total C) to approximately 50 SCB/1000 total C, where total C=carbons in backbone+carbons in branches. Each standard had a weight-average molecular weight from 36,000 g/mole to 126,000 g/mole, as determined by the GPC-LALS processing method described above. Each standard had a molecular weight distribution (Mw/Mn) from 2.0 to 2.5, as determined by the GPC-LALS processing method described above. Polymer properties for the SCB standards are shown in Table A.
The “IR5 Area Ratio (or “IR5Methyl Channel Area/IR5Measurement Channel Area”)” of “the baseline-subtracted area response of the IR5 methyl channel sensor” to “the baseline-subtracted area response of IR5 measurement channel sensor” (standard filters and filter wheel as supplied by PolymerChar: Part Number IR5_FWM01 included as part of the GPC-IR instrument) was calculated for each of the “SCB” standards. A linear fit of the SCB frequency versus the “IR5 Area Ratio” was constructed in the form of the following Equation 4B:
SCB/1000totalC=A0+[A1×(IR5Methyl Channel Area/IR5Measurement Channel Area)] (Eqn. 4B),
where A0 is the “SCB/1000 total C” intercept at an “IR5 Area Ratio” of zero, and A1 is the slope of the “SCB/1000 total C” versus “IR5 Area Ratio,” and represents the increase in the “SCB/1000 total C” as a function of “IR5 Area Ratio.”
A series of “linear baseline-subtracted chromatographic heights” for the chromatogram generated by the “IR5 methyl channel sensor” was established as a function of column elution volume, to generate a baseline-corrected chromatogram (methyl channel). A series of “linear baseline-subtracted chromatographic heights” for the chromatogram generated by the “IR5 measurement channel” was established as a function of column elution volume, to generate a base-line-corrected chromatogram (measurement channel).
The “IR5 Height Ratio” of “the baseline-corrected chromatogram (methyl channel)” to “the baseline-corrected chromatogram (measurement channel)” was calculated at each column elution volume index (each equally-spaced index, representing 1 data point per second at 1 ml/min elution) across the sample integration bounds. The “IR5 Height Ratio” was multiplied by the coefficient A1, and the coefficient A0 was added to this result, to produce the predicted SCB frequency of the sample. The result was converted into mole percent comonomer, as follows in Equation 5B:
Mole Percent Comonomer={SCBf/[SCBf+((1000−SCBf*Length of comonomer)/2)]}*100 (Eqn. 5B),
where “SCBf” is the “SCB per 1000 total C” and the “Length of comonomer”=8 for octene, 6 for hexene, and so forth.
Each elution volume index was converted to a molecular weight value (Mwi) using the method of Williams and Ward (described above; Eqn. 1B). The “Mole Percent Comonomer (y axis)” was plotted as a function of Log(Mwi), and the slope was calculated between Mwi of 15,000 and Mwi of 150,000 g/mole (end group corrections on chain ends were omitted for this calculation). An EXCEL linear regression was used to calculate the slope between, and including, Mwi from 15,000 to 150,000 g/mole. This slope is defined as the molecular weighted comonomer distribution index (MWCDI=Molecular Weighted Comonomer Distribution Index).
Representative Determination of MWCDI (Inventive First Composition 2) A plot of the measured “SCB per 1000 total C(=SCBf)” versus the observed “IR5 Area Ratio” of the SCB standards was generated (see
The “IR5 Height Ratio” was determined for Inventive Example 2 (see integration shown in
The SCBf was converted into “Mole Percent Comonomer” via Equation 5B. The “Mole Percent Comonomer” was plotted as a function of polyethylene-equivalent molecular weight, as determined using Equation 1B, as discussed above. See
The following physical properties were measured on the films produced (see experimental section).
Samples measured for internal haze and overall (total) haze were sampled and prepared according to ASTM D1003. Internal haze was obtained via refractive index matching using mineral oil on both sides of the films. A Hazeguard Plus (BYK-Gardner USA; Columbia, Md.) was used for testing. Surface haze was determined as the difference between total haze and internal haze. The total haze was reported as the average of five measurements.
The Elmendorf Tear test determines the average force to propagate tearing through a specified length of plastic film or non rigid sheeting, after the tear has been started, using an Elmendorf-type tearing tester.
After film production from the sample to be tested, the film was conditioned for at least 40 hours at 23° C. (+/−2° C.) and 50% R.H (+/−5) as per ASTM standards. Standard testing conditions were 23° C. (+/−2° C.) and 50% R.H (+/−5) as per ASTM standards.
The force, in grams, required to propagate tearing across a film or sheeting specimen was measured using a precisely calibrated pendulum device. In the test, acting by gravity, the pendulum swung through an arc, tearing the specimen from a precut slit. The specimen was held on one side by the pendulum and on the other side by a stationary member. The loss in energy by the pendulum was indicated by a pointer or by an electronic scale. The scale indication was a function of the force required to tear the specimen.
The sample specimen geometry used in the Elmendorf tear test was the ‘constant radius geometry,’ as specified in ASTM D1922. Testing is typically carried out on specimens that have been cut from both the film MD and CD directions. Prior to testing, the film specimen thickness was measured at the sample center. A total of 15 specimens per film direction were tested, and the average tear strength and average thickness reported. The average tear strength was normalized to the average thickness.
The film MD (Machine Direction) and CD (Cross Direction) secant modulus and tensile break strength (or tensile strength) were measured with an Instron universal tester according to ASTM D882-10. The reported secant modulus value was the average of five measurements. The tensile break strength was determined using five film samples in each direction, with each sample being “1 inch×6 inches” in size.
The Puncture test determines the resistance of a film to the penetration of a probe at a standard low rate, a single test velocity. The puncture test method is based on ASTM D5748. After film production, the film was conditioned for at least 40 hours at 23° C. (+/−2° C.) and 50% R.H (+/−5), as per ASTM standards. Standard testing conditions are 23° C. (+/−2° C.) and 50% R.H (+/−5), as per ASTM standards. Puncture was measured on a tensile testing machine. Square specimens were cut from a sheet to a size of “6 inches by 6 inches.” The specimen was clamped in a “4 inch diameter” circular specimen holder, and a puncture probe was pushed into the centre of the clamped film at a cross head speed of 10 inches/minute. The internal test method follows ASTM D5748, with one modification. It deviated from the ASTM D5748 method, in that the probe used was a “0.5 inch diameter” polished steel ball on a “0.25 inch” support rod (rather than the 0.75 inch diameter, pear shaped probe specified in D5748).
There was a “7.7 inch” maximum travel length to prevent damage to the test fixture. There was no gauge length; prior to testing, the probe was as close as possible to, but not touching the specimen.
A single thickness measurement was made in the centre of the specimen. For each specimen, the maximum force, the force at break, the penetration distance, and the energy to break were determined. A total of five specimens were tested to determine an average puncture value. The puncture probe was cleaned using a “Kim-wipe” after each specimen.
The film Dart Drop test determines the energy that causes a plastic film to fail, under specified conditions of impact by a free falling dart. The test result is the energy, expressed in terms of the weight of the missile falling from a specified height, which would result in the failure of 50% of the specimens tested.
After the film was produced, it was conditioned for at least 40 hours at 23° C. (+/−2° C.) and 50% R.H (+/−5), as per ASTM standards. Standard testing conditions are 23° C. (+/−2° C.) and 50% R.H (+/−5), as per ASTM standards.
The test result was reported as either by Method A, which uses a 1.5″ diameter dart head and 26″ drop height, or by Method B, which uses a 2″ diameter dart head and 60″ drop height. The sample thickness was measured at the sample center, and the sample then clamped by an annular specimen holder with an inside diameter of 5 inches. The dart was loaded above the center of the sample, and released by either a pneumatic or electromagnetic mechanism.
Testing was carried out according to the ‘staircase’ method. If the sample failed, a new sample was tested with the weight of the dart reduced by a known and fixed amount. If the sample did not fail, a new sample was tested with the weight of the dart increased by a known amount. After 20 specimens had been tested, the number of failures was determined. If this number was 10, then the test is complete. If the number was less than 10, then the testing continued, until 10 failures had been recorded. If the number was greater than 10, testing was continued, until the total of non-failures was 10. The Dart Drop strength was determined from these data, as per ASTM D1709, and expressed in grams, as either the Dart Drop Impact of Type A or Type B. In some cases, the sample Dart Drop Impact strength may lie between A and B. In these cases, it is not possible to obtain a quantitative dart value.
Ultimate stretch is tested on a Highlight Film Test System from Highlight Industries. A film roll is placed on the unwind section of the machine and the film is passed through a set of rollers. The film is then unwound with increasing force until it reaches its ultimate stretch point. Load cells measure the amount of force applied and a calculation is made to determine the amount of stretch present in the film, measured in percent. The stretch force @200% is also determined.
This test uses a Bruceton staircase method to determine the maximum force to load at which the film can be passed over a test probe for three wraps with no failures. The test probe is inserted into the test stand at the desired protrusion distance. The film is positioned such that the test probe is aligned with the center of the film. The film is attached to the test stand and the wrapper started. Once the wrapper reaches the designated target for pre-stretch, the film is allowed to pass over the probe for a maximum of three wraps. Any breakage of the film during any of the wrap is considered a failure at that force to load setting. Depending on the performance of the film at the load setting (i.e. passed or failed), the force to load is adjusted up or down, and the test is repeated at the new load setting. This continues until the maximum force at which no failures occurs is found. The equipment and settings used in this method are as follows:
The following examples illustrate the present invention, but are not intended to limit the scope of the invention.
Inventive first compositions 1, 2 and 3, each contain two ethylene-octene copolymers. Each composition was prepared, via solution polymerization, in a dual series loop reactor system according to U.S. Pat. No. 5,977,251 (see
The first catalyst system comprised a bis((2-oxoyl-3-(dibenzo-1H-pyrrole-1-yl)-5-(methyl)phenyl)-2-phenoxymethyl)-methylene-1,2-cyclohexanediylhafnium (IV) dimethyl, represented by the following formula (CAT 1):
The molar ratios of the metal of CAT 1, added to the polymerization reactor, in-situ, to that of Cocat1 (modified methyl aluminoxane), or Cocat2 (bis(hydrogenated tallow alkyl)methyl, tetrakis(pentafluorophenyl)borate(1-) amine), are shown in Table 1.
The second catalyst system comprised a Ziegler-Natta type catalyst (CAT 2). The heterogeneous Ziegler-Natta type catalyst-premix was prepared substantially according to U.S. Pat. No. 4,612,300, by sequentially adding to a volume of ISOPAR E, a slurry of anhydrous magnesium chloride in ISOPAR E, a solution of EtAlCl2 in heptane, and a solution of Ti(O-iPr)4 in heptane, to yield a composition containing a magnesium concentration of 0.20M, and a ratio of Mg/Al/Ti of 40/12.5/3. An aliquot of this composition was further diluted with ISOPAR-E to yield a final concentration of 500 ppm Ti in the slurry. While being fed to, and prior to entry into, the polymerization reactor, the catalyst premix was contacted with a dilute solution of Et3Al, in the molar Al to Ti ratio specified in Table 1, to give the active catalyst.
The polymerization conditions for the inventive first compositions 1, 2 and 3 are reported in Table 1. As seen in Table 1, Cocat. 1 (modified methyl aluminoxane (MMAO)); and Cocat. 2 (bis(hydrogenated tallow alkyl)methyl, tetrakis(pentafluorophenyl)borate(1-) amine) were each used as a cocatalyst for CAT 1. Additional properties of the inventive compositions 1, 2 and 3 were measured, and are reported in Table 2. The GPC MWD profiles, and corresponding comonomer distribution overlays, are shown in
Comparative compositions A and B, each contain two ethylene-octene copolymers, and each was prepared, via solution polymerization, in a dual loop reactor system, in the presence of a first catalyst system, as described below, in the first reactor, and a second catalyst system, as described below, in the second reactor. The first catalyst system comprised titanium, [N-(1,1-dimethylethyl)-1,1-dimethyl-1-[(1,2,3,3a,8a-η)-1,5,6,7-tetrahydro-2-methyl-s-indacen-1-yl]silanaminato(2-)-κN][(1,2,3,4-η)-1,3-pentadiene]-(CAT 3, a constrained geometry catalyst). The second catalyst system comprised the Ziegler-Natta premix (CAT 2), as discussed above.
The polymerization conditions for comparative compositions A and B are reported in Table 1. As seen in Table 1, Cocat. 1 (modified methyl aluminoxane (MMAO)) and Cocat. 2 (bis(hydrogenated tallow alkyl)methyl, tetrakis(pentafluorophenyl)borate(1-) amine) were each used as cocatalyst for CAT 3. Additional properties of the comparative compositions A and B were measured, and are reported in Table 2. The GPC MWD profiles, and corresponding comonomer distribution overlays, are shown in
Comparative C is an ethylene-hexene copolymer composition, commercially available under the commercial designation EXCEED 1018CA from EXXONMOBIL Chemical Company, and having a density of approximately 0.918 g/cm3, a melt index (I2 or I2), measured at 190° C. and 2.16 kg, of approximately 1.0 g/10 minutes. Additional properties of the comparative example C were measured, and are reported in Table 2. The GPC MWD profile, and corresponding comonomer distribution overlay, is shown in
Comparative D is an ethylene-octene copolymer composition, provided by The Dow Chemical Company, under the commercial designation ELITE 5230G, and having a density of approximately 0.916 g/cm3, a melt index (I2 or I2), measured at 190° C. and 2.16 kg, of approximately 4.0 g/10 minutes. Additional properties of the comparative example D were measured, and are reported in Table 2. The GPC MWD profile, and corresponding comonomer distribution overlay, is shown in
Monolayer cast films of inventive composition 3 and comparative composition D were fabricated on a 5 layer, Egan Davis Standard coextrusion cast film line. Film thickness was maintained at 0.8 mil (0.0008 in or 0.02 mm). The cast line consisted of three 2½″ and two 2″ “30:1 L/D Egan Davis Standard MAC extruders,” which are air cooled. All extruders had moderate work DSB (Davis Standard Barrier) type screws. A CMR 2000 microprocessor monitored and controlled the operations. The extrusion process was monitored by pressure transducers, located before, and after, the breaker plate, as well as by four heater zones on each barrel, one each at the adapter and the block and two zones on the die. The microprocessor also tracked the extruder RPM, % FLA, HP, rate, line speed, % draw, primary and secondary chill roll temperatures, gauge deviation, layer ratio, rate/RPM, and melt temperature for each extruder.
Equipment specifications included a Cloeren 5 layer, dual plane feed block, and a Cloeren 36″ Epich II autogage 5.1 die. The primary chill roll had a matte finish, and was 40″ O.D.×40″ long, with a 30-40 RMS surface finish for improved release characteristics. The secondary chill roll is 20″ O.D.×40″ long, with a 2-4 RMS surface for improved web tracking. Both the primary and secondary chill rolls had chilled water circulating through them to provide quenching. There was an NDC Beta gauge sensor for gauge thickness and automatic gauge control, if needed. Rate was measured by five Barron weigh hoppers, with load cells on each hopper for gravimetric control. Samples were finished on the two position, single turret Horizon winder, on 3″ I.D. cores, with center wind automatic roll changeover and slitter station. The maximum throughput rate for the line was “600 pounds per hour,” and maximum line speed was “900 feet per minute.” Film properties are shown in Table 3.
Monolayer cast films for inventive composition 3 and comparative composition D were fabricated based on the following conditions:
It has been discovered, that for cast films, inventive example 3 showed significantly higher toughness (as indicated by dart drop impact values) than comparative composition D. It is believed that the improved film toughness from the inventive compositions is a result of their high MWCDI values. From a molecular structure standpoint, a high MWCDI value indicates comonomers are more favorably incorporated (a higher incorporation of comonomer and a better distribution of comonomer) in the high molecular weight polymer molecules, rather than in the low molecular weight polymer molecules. The inventive compositions also have low LCB, as indicated by low ZSVR, as compared to conventional polymers. As a result the polymer contains more tie chains, and therefore, provides better film toughness. The inventive compositions also have significantly high I10/I2 values, indicating good processability of these compositions.
In this example, inventive composition 4 is the same as inventive composition 3 (above) and was prepared in the same way as inventive composition 3. For clarity in discussing the results, it is referred to as inventive composition 4 in this example because a different cast film is formed from it. Inventive composition 5 contains an ethylene-octene copolymer. Inventive composition 5 was prepared in the same manner and using the same catalyst system as inventive compositions 1-3, with the exception of the polymerization conditions which are reported in Table 4.
Comparative composition E is an ethylene-octene copolymer composition, commercially available under the commercial designation ELITE 5230G from the Dow Chemical Company, and having a density of approximately 0.916 g/cm3 and a melt index (I2 or I2), measured at 190° C. and 2.16 kg, of approximately 4.0 g/10 minutes. Additional properties of the comparative composition E were measured, and are reported in Table 5.
Monolayer cast films of inventive compositions 4 and 5, and of comparative composition E, were fabricated on a 5 layer Egan Davis Standard coextrusion cast film line. The cast line consisted of three 2½″ and two 2″ 30:1 L/D Egan Davis Standard MAC extruders, which are air cooled. All extruders had moderate work DSB (Davis Standard Barrier) type screws. A CMR 2000 microprocessor monitored and controlled the operations. The extrusion process was monitored by pressure transducers, located before, and after, the breaker plate, as well as by four heater zones on each barrel, one each at the adapter and the block and two zones on the die. The microprocessor also tracked the extruder RPM, % FLA, HP, rate, line speed, % draw, primary and secondary chill roll temperatures, gauge deviation, layer ratio, rate/RPM, and melt temperature for each extruder.
Equipment specifications included a Cloeren 5 layer, dual plane feed block, and a Cloeren 36″ Epich II autogage 5.1 die. The primary chill roll had a matte finish, and was 40″ O.D.×40″ long, with a 30-40 RMS surface finish for improved release characteristics. The secondary chill roll is 20″ O.D.×40″ long, with a 2-4 RMS surface for improved web tracking. Both the primary and secondary chill rolls had chilled water circulating through them to provide quenching. There was an NDC Beta gauge sensor for gauge thickness and automatic gauge control, if needed. Rate was measured by five Barron weigh hoppers, with load cells on each hopper for gravimetric control. Samples were finished on the two position single turret Horizon winder, on 3″ I.D. cores, with center wind automatic roll changeover and slitter station. The maximum throughput rate for the line was “600 pounds per hour,” and maximum line speed was “900 feet per minute.”
Monolayer cast films for inventive compositions 4 and 5, and for comparative composition E, were fabricated based on the following conditions to provide films having a nominal thickness of 0.8 mils (0.0008 inches):
Monolayer cast films for inventive compositions 4 and 5, and for comparative composition E, were also fabricated based on the following conditions to provide films having a nominal thickness of 0.5 mils (0.0005 inches):
It has been discovered, that for cast films, inventive examples 4 and 5 showed significantly higher toughness (as indicated by dart drop impact values) than comparative composition E. It is believed that the improved film toughness from the inventive compositions is a result of their high MWCDI values. From a molecular structure standpoint, a high MWCDI value indicates comonomers are more favorably incorporated (a higher incorporation of comonomer and a better distribution of comonomer) in the high molecular weight polymer molecules, rather than in the low molecular weight polymer molecules. The inventive compositions also have low LCB, as indicated by low ZSVR, as compared to conventional polymers. As a result the polymer contains more tie chains, and therefore, provides better film toughness. The inventive compositions also have significantly high I10/I2 values, indicating good processability of these compositions.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2015/037871 | 6/26/2015 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62017525 | Jun 2014 | US | |
| 62152414 | Apr 2015 | US |
