MXPA97003565A - Compositions of extrusion that have standing and rebordeo towards adustrosustantially reduc - Google Patents

Abstract

The present invention relates to an ethylene polymer extrusion composition comprising from about 75 to 95 percent, by weight of the total composition, of at least one ethylene / alpha-olefin interpolymer selected from the group consisting of a polymer of substantially linear ethylene, a homogeneously branched linear ethylene polymer and a heterogeneously branched linear ethylene polymer, wherein the ethylene / alpha-olefin polymer is characterized as having a density in the range of 0.85 grams / cubic centimeters to 0.940 grams / cubic centimeters and from about 5 to 25 percent, by weight of the total composition, of at least one high-pressure ethylene polymer characterized by having a melt index, I2, less than 6.0 grmoas / 10 minutes, a density of minus 0.916 grams / cubic centimeter, a melt strength of at least 9 cN as determined using a unit of Got tfert Rheotens at 190 ° C, a ratio of Mw / Mn of at least 7.0 and a molecular weight distribution determined by gel permeation chromatography, where the ethylene polymer extrusion composition has a melt index I2, at least 1.0 gram / 10 minut

Description

EXTRUSION COMPOSITIONS THAT HAVE HIGH STRETCHING AND REBORNATION TOWARDS SUBSTANTIALLY REDUCED INPUT This invention relates to polyethylene extrusion compositions. In particular, the invention relates to an ethylene polymer extrusion composition having high stretch and substantially reduced inward flanging. This invention also relates to a method for making the ethylene polymer extrusion composition and a method for making an extrusion coated article, an article in the form of an extrusion profile and an article in the form of an extrusion mold film. . It is known that low density polyethylene (DPE) made by low pressure polymerization of ethylene with free radical initiators as well as ultra low density polyethylene (ULDPE) made by the copolymerization of ethylene and α-olefins with catalysts (metal transition) of conventional Ziegler at low to medium pressure can be used, for example, for extrusion coating substrates such as cardboard, for preparing extrusion mold film for applications such as disposable diapers and food packaging and for preparing profiles of Extrusion as wire sleeve and cable. However, although low density polyethylene generally exhibits excellent extrusion processability and high extrusion stretch speeds, low density polyethylene extrusion compositions lack sufficient abuse resistance and toughness for many applications. For purposes of extrusion coating and extrusion molding, efforts to improve the abuse resistance properties by providing low density polyethylene compositions having high molecular weights (i.e., having melting index, I2, lower than approximately 2 g / 10) since these compositions inevitably have too much resistance to melting to be stretched successfully at high line speeds. Although heterogeneous linear low density polyethylene and ultra low density polyethylene extrusion compositions offer improved abuse resistance and toughness properties and the medium density polyethylene (MDPE) extrusion compositions offer improved barrier strength, these ethylene polymers Linear extrusions can not be extruded or stretched at high takeoff speeds and are now known to exhibit relatively poor extrudability processability. The final extrusion stretch velocity of the ethylene α-olefin interpolymers is limited (at otherwise practicable extrusion line speeds) by the emergence of a melt flow instability phenomenon known as stretch resonance rather than being limited for melt stress fractures due to "hardening stress" which occurs at higher line speeds and is typical for low density polyethylene and other highly branched high pressure ethylene polymers, such as ethylene copolymers -acrylic acid (EAA) and ethylene-vinyl acetate (EVA) copolymers. The "stretch resonance" or "oscillation of the molten substance" occurs in heterogeneous linear low density polyethylene, ultra low density polyethylene and other linear polymers such as high density polyethylene (HDPE), polypropylene and polyester during the processing that involves rapid stretching or pulling of the mixture such as extrusion coating, extrusion molded film manufacturing, profile extrusion and fine denier fiber spinning. Also, the emergence or occurrence of stretch resonance is unequivocal. The teachings of the Kurtz et al patent in U.S. Patent Number: 4,339,507 and Lucchesi et al. In U.S. Patent Number: 4,486,377 describe the stretch resonance as a randomly sustained oscillation and / or periodic, variation or pulsation of the molten polymer with respect to the velocity and cross-sectional area of a melt-stretching process that occurs between the die and the take-off position when the boundary conditions are a fixed speed in the die and a fixed velocity are the starting position. Stretch resonance occurs when the stretch ratio (that is, the melt velocity at takeoff divided by the instantaneous melt velocity at the outlet of the die often which approximates by dividing the reciprocal of the final thickness of the polymer between the reciprocal the thickness of the instantaneous melt at the outlet of the die) exceeds a specific critical value of the polymer. Stretch resonance is a melt flow instability that manifests as irregularities in the final dimensions of coating, film or fiber and frequently produces widely varying thicknesses and widths. When the line speeds significantly exceed the rate of emergence, the stretch resonance can cause tissue or filament ruptures and thereby interrupt the entire process of stretching or conversion. Given the different differences and profusion of details that may exist between different extrusion equipment, the relative strength of the stretching rensonance is often expressed in terms of critical stretch ratio, and for conventional linear ethylene polymers, it has been found that the proportions Stable stretch maxims are less than 10: 1, although stretch ratios greater than 20: 1 are required for most commercial stretching operations. "Stretch" is defined herein to mean to stretch or elongate an extruded product of molten polymer (fabric or filament) in the machine direction and occasionally (simultaneously to a lesser degree) also in the transverse direction. "Resistance of the molten product" to what is also called in the medium as "molten product tension" is defined and quantified herein as the voltage or force (applied by means of a winding drum equipped with a voltage cell) required to stretch a molten extruded substance at a specific rate above its melting point as it passes through the die of a standard plastometer as described in AST D1238-E. The stress values of the molten product, which are reported herein are centi-Newtons (cN), are determined using a Gottfert Rheotens at 190 ° C. In general, for ethylene α-olefin interpolymers and high pressure ethylene polymers, the melt tension tends to increase with increased molecular weight, or with increasing molecular weight distribution and / or with increased melt flow rates. . "Inward beading" which is influenced by swelling of the extruded product and, to a lesser extent, by effects of surface tension is defined herein as the difference between the width of the die and the width of the extruded product in the take-off position. or the final width of the manufactured article. The measured values of the inward flange (at constant production) will remain constant or decrease as the stretch rate decreases, and, in general, it is well known that for conventional ethylene polymers the values of inward flange increase as the molecular weight decreases and / or as the molecular weight distribution becomes thinner. The inward flange values reported herein are determined at an extrusion coating weight of a 1 mil (0.025 millimeter) layer using a Black Clawson L / D 30: 1 extrusion coater equipped with a 30 inch die ( 76.2 cm) wide with barbs up to 24 inches (61 centimeters) and having a depth of 20-mil (0.51 mm) and 50 pounds (22.7 kg) of brown paper. The "take-off position" is defined herein to refer to the point of contact (either at the top or bottom) of a roller device that stretches or pulls the molten product for extrusion from its instantaneous initial thickness at the outlet of the product. Die to its final thickness. The roller device can be a roller of ni, a rubber roller, an abrupt cooling roller, a combination thereof or the like constructed of, for example, metal or rubber with various surfaces with finishes such as polished, matt or etched; all of which can in varying degrees affect the beginning of the stretch resonance. A variety of potential solutions have been described for directing the tendencies of inward flanging and / or stretch resonance of the ethylene α-olefin interpolymers. Many of these solutions are related to the equipment and others relate mainly to the modification of the properties of the ethylene α-olefin interpolymer by the formation of a polymer mixture with a highly branched high pressure ethylene polymer such as, for example, polyethylene of low density. Thompson in U.S. Patent No. 4,348,346 is an example of attempts related to the equipment for directing inward flange and stretch resonance. Thompson describes a secondary injection of polymer fusions that flows into the primary die at the edges of the primary weft flow described to reduce inward beading and provides improved edge burr control. Cancio et al., In U.S. Patent No. 4,668,463 and in U.S. Patent No. 4, 626, 574, provides a solution to a specific modification to delay the onset of stretch resonance. where locating a stretch roller no more than 6 inches (15.2 centimeters) from the die provides a short air / stretch space and reduces stretch resonance. Luchessi et al., In U.S. Patent No. 4,486,377, teaches the use of a fluid medium, for example, nitrogen, carbon monoxide or air, directed against the molten web before the takeoff position as a method. viable to slow the stretch resonance. Similarly, Krutz et al., In U.S. Patent No. 4,608,221, discloses that stretch resonance can be mitigated by the use of a tensioning device with a frictionless surface in a "rapid cooling zone" between the die and the take-off position. On the contrary, as another example of modification of the equipment to alleviate to reduce the stretch resonance, Chaing, in US Pat. No. 4,859,379 discloses the radiant heating of the melted web before a takeoff position to a roller Cooling. Examples of ethylene α-olefin interpolymer compositions having reduced stretch resonance include U.S. Patent No. 4,378,451 (Edwards) which discloses compositions with a high flow rate regime based on degraded propylene polymers blended with low density polyethylene. A similar example is provided by Erkman et al., In U.S. Patent No. 3,247,290 wherein the thermally degraded high density polyethylene (low viscosity) is mixed with low density polyethylene to prepare coating compositions. Another example of an ethylene α-olefin interpolymer mixture integrating low density polyethylene is described by Kurtz et al. In U.S. Patent No. 4,339,507, where high pressure low density polyethylene in 20 to 98 percent of the weight combined with a heterogeneous linear low density polyethylene is shown to provide extrusion coating compositions with improved performance regimes. EP 0601495 A2 discloses a blend composition for extruded forms that has improved workability and excellent transparency, heat resistance, low temperature, impact resistance, heat sealing and food sanitation. The composition contains as component (A) from 50 to 99 weight percent of a heterogeneous linear low density polyethylene having specific properties such as a single fractionation peak by elution with temperature rise (TREF) and as a component (B). ) from 1 to 50 weight percent of a low density polyethylene having specific properties such as a melt flow rate of 0.1 to 2 g / 10 minutes, a memory effect (ME) of not less than 1.3 and a melting voltage (MT) of not less than 1.0 gram. This description is directed to blown or inflated film, generally shows mixing with large amounts of low density polyethylene as component (B) and does not direct requirements for improved resistance to stretch resonance. A WPI summary of Derwent, Access No. 85-130999 / 22, discloses a polyethylene extrusion coating composition containing a radical polymerized high pressure polyethylene and an ethylene / copolymer. ion-polymerized olefin. The high pressure polyethylene component has a melt index of at least 1.0 gram / 10 minutes and Mw / Mn of at least 6.0. The summary shows that the higher the M / Mn ratio of the high pressure polyethylene, the longer the branching of the long chain, which increases the elasticity of the melt and reduces the inward flanging in the extrusion coating. Similar to EP 0601 495 A2, this summary generally shows a mixture with large amounts of low density polyethylene (eg, 20 to 50 weight percent) and does not originate specific requirements to ensure improved strength to the Stretch resonance during coating or extrusion molding. EP 0 095 253 A1 discloses a mixture of polyethylene containing heterogeneous linear low density polyethylene and not less than one weight percent free radical catalyzed polyethylene having high die swelling and a molten flow rate. below 50. This description is directed to the film by blowing and does not provide samples on the behavior of the resonance and inward flanging. Hodgson and co-workers in WO 94/06857 disclose a mixture to provide soft films having highlighted physical properties. The mixture has two components wherein each component is defined by a respiration rate value of the composition and used in large quantities over a wide concentration range. An example of compositions that reduce stretch resonance without the inclusion of a step of degradation of the polymer and / or mixing with a branched high-pressure ethylene polymer is shown by Dohrer et al. In U.S. Patent No. 4,780,264 where heterogeneous linear low density polyethylene with blend of melt flow rates of less than 83 (ie, using even narrower molecular weight distributions than those typically employed) was found to allow, surprisingly, velocities of line in extrusion coating and extrusion molding. However, predictably, these materials also have a greater inward beading and / or lower extrusion processing capacity (eg, higher extruder amperage). In WO 95/01250, Obijeski et al. Describe a process for extruding a thermoplastic composition at higher drawing rates with less inward beading and greater resistance to stretch resonance. The composition is made from at least one substantially linear ethylene polymer used alone or in combination with at least one high pressure ethylene polymer and / or with at least one heterogeneous linear olefin polymer. Although this composition is clearly improved over ordinary ethylene / or-olefin compositions, the inward flanging of the composition is typically undesirably high. Despite various advances, there is still a need to avoid the issues of stretch resonance and inward flanging when extruding ethylene to olefin interpolymer compositions, particularly at high extrusion line speeds. For example, although the compositions described in U.S. Pat. No. 5, 395,471 exhibit significantly increased line speeds (stretching regimes), high resistance to stretch resonance and reduced inward beading with respect to conventional linear ethylene to olefin compositions, those compositions still have a high inward beading (e.g. , >7 inches (17.8 centimeters) to 1.0 mil (0.025 millimeters) of coating weight per extrusion). Further, where ordinary high pressure ethylene polymers are used as the component polymers of the blend in the ethylene α-olefin polymer compositions to increase line speed, resistance to stretch resonance and inward flanging, to effect such an increase relatively high concentrations (ie, greater than 20 weight percent based on the total weight of the composition) of the high pressure ethylene polymer as a polymer component of the mixture are required. However, where a resin manufacturer or converter has a limited capacity, such as, for example, where the only equipment available for the purpose of addition is a small-scale weight feeder, the requirement of higher concentrations of one component of the High-pressure ethylene polymer mixture can be prohibitive.

As described hereinafter, the present invention substantially covers the need for ethylene polymer extrusion compositions having high line speeds, high resistance to stretch resonance and substantially reduced inward flanging, and a method for make those compositions using low capacity addition equipment. The compositions of the present invention can be used together with known modifications to the equipment and in combination with thermally degraded polymers with good advantages and also known solutions can be made with the combined or synergistic benefits of the present invention. In addition to the advantage of being able to make an improved extrusion composition by using a wide variety of mixing equipment options, converters and manufacturers can now realize the advantages of improved properties over the abuse or barrier (due to the use of ethylene α-olefin interpolymers), higher productivity regimes (due to the ability to obtain higher line speeds) and decrease in measurements (smaller coating weights or thinner films and profiles), although they still prepare coatings , profiles and high quality uniform films. Another advantage of the invention is the strength of the molten product of the composition of the invention related to the unmodified ethylene / α-olefin interpolymer. This increased melt strength can allow improved part definition, less buckling and greater resistance to the untreated compound in profile extrusions such as the manufacture of wire products and cables. In accordance with the present invention, we have discovered an improved method of making a composition for the extrusion of ethylene polymer, an improved ethylene polymer extrusion composition, and a method for making an extrusion coated substrate, an extrusion profile of an ethylene polymer composition and an extrusion mold film of the ethylene polymer composition. One aspect of the invention is an ethylene polymer extrusion composition comprising from 75 to 95 percent, by weight of the total composition, of at least one ethylene / α-olefin interpolymer, selected from the group consisting of substantially linear ethylene polymer, wherein the ethylene / α-olefin polymer is characterized as having a density in the range of 0.85 grams / cubic centimeter to 0.940 grams / cubic centimeter and from 5 to 25 percent, by weight of the composition total, of at least one high pressure ethylene polymer, characterized by having a melt index, I2, less than 6.0 grams / 10 minutes, a density of at least 0.916 grams / cubic centimeter, a melt strength of at least 9 cN determined using a Gottfert Rheotens unit at 190 ° C, a Mw / Mn ratio of at least 7.0 determined by gel permeation chromatography and a determined bimodal molecular weight distribution. or by gel permeation chromatography, wherein the extrusion composition of the ethylene polymer has a melt index, I2, of at least 1.0 gram / 10 minutes. Another aspect of the invention is a process for making an ethylene polymer extrusion composition comprising: (a) combining from 5 to 25 percent, by weight of the extrusion composition, of at least one ethylene polymer at high pressure with from 75 to 95 percent, by weight of the extrusion composition, of at least one ethylene α-olefin interpolymer, wherein at least the high pressure ethylene polymer is combined using addition equipment that is part of the process of polymerization to prepare at least one ethylene α-olefin interpolymer, the extrusion composition of the ethylene polymer having a melt index, I 2, of at least 1.0 grams / 10 minutes and an inward flange of 1 thousand (0.025 millimeters) in an extrusion coating of a layer with a weight at least 12 percent lower than the expected value of inward flanging for the composition, and (b) collecting or transporting the extrusion composition in a form suitable for a subsequent use. Yet another aspect of the invention is a process for using a composition for extrusion of ethylene polymer to make an extrusion coated substrate, an extrusion profile or an extrusion mold film comprising: (i) feeding a polymer composition of ethylene within at least one extruder of an extrusion line, wherein the composition of the ethylene polymer comprises from 75 to 95 percent, by ht of the total composition, of at least one ethylene / α-olefin interpolymer selected from the group consisting of consists of a substantially linear polymer, a linearly branched homogeneous linear ethylene polymer and a heterogeneously branched linear ethylene polymer, wherein the ethylene / α-olefin polymer is characterized as having a density in the range of 0.85 grams / cubic centimeter to 0.940 grams / cubic centimeter and a melt index, I2, in the range of 0.1 to 50 grams / 10 minutes, and from 5 to 25 percent, by ht of the total composition, of at least one high pressure ethylene polymer, characterized by having a melt index, I2, of less than 1.0 grams / 10 minutes, a density of at least 0.916 grams / cubic centimeter, a strength of the molten product of at least 9 cN determined using a Gottfert Rheotens unit at 190 ° C, a M ^ / Q ratio of at least 7.0 determined by gel permeation chromatography and a bimodal molecular ht distribution determined by gel permeation chromatography , and wherein the extrusion composition of the ethylene polymer has a melt index, I, of at least 1.0 grams / 10 minutes, (ii) melting and mixing the ethylene polymer composition to form at least one stream of molten polymer uniform, (iii) operate the extrusion line at line speeds greater than 152 meters / minute, (iii) extrude the molten polymer stream through a die to form a primary extruded product, and either (a) stretch and cool the extruded product to prepare the extruded profile of at least one layer of the extrusion composition of the ethylene polymer, or (b) stretch the extrudate into the substrate by which will coat the substrate with at least one layer of extrusion composition of the ethylene polymer, or (c) stretch and cool the extrudate in a take-off device to make the film with at least one layer of the composition, and (vi) ) transport or collect the profile, the coated substrate or the film for subsequent use. A further aspect of the invention is an article comprising at least one layer of an extrusion composition of an ethylene polymer, wherein the extrusion composition comprises from 75 to 95 percent, by ht of the total composition, at least an ethylene / α-olefin interpolymer selected from the group consisting of a substantially linear polymer, a homogenously branched linear ethylene polymer and a heterogeneously branched linear ethylene polymer, wherein the ethylene / α-olefin polymer is characterized as having a density in the range of 0.85 grams / cubic centimeter to 0.940 grams / cubic centimeter and from 5 to 25 percent, by ht of the total composition, of at least one high pressure ethylene polymer, characterized by having a melt index , I, less than 6.0 grams / 10 minutes, a density of at least 0.916 grams / centric cubic meter, a resistance of the molten product of at least 9 cN determined using a Gottfert Rheotens unit at 190 ° C, a MW / MQ ratio of at least 7.0 determined by gel permeation chromatography and where the extrusion composition of the ethylene polymer has a melt index, I2, of when minus 1.0 grams / 10 minutes.

With the present invention, one obtains reduced inward flanging, higher drawing rates, and greater resistance to stretch resonance than obtainable with known polymer blends or unmodified ethylene α-olefin interpolymer compositions. Figure 1 is a graphical illustration of the molecular weight distribution determined using gel permeation chromatography of a high pressure ethylene polymer composition suitable for use in the present invention. Figure 2 is a graphic illustration of the molecular weight distribution and the comparative bimodality (determined using gel permeation chromatography) of four different compositions of high pressure ethylene polymer. Figure 3 is a graph of the resistance of the molten product against inward flanging in 1 mil (0.025 millimeters) for low density polyethylene resins which is used to predict, by extrapolation, the inward flanging behavior of the resins that they can not be stretched due to excessive resistance of the molten product. The composition of the invention comprises from 75 to 95 percent, preferably 80 to 95 percent, more preferably 85 to 95 percent, most preferably 88 to 95 percent based on the total weight of the composition, of at least one ethylene α-olefin interpolymer and from 5 to 75 percent, preferably from 5 to 75 percent, more preferably from 5 to 15 percent, most preferably from 5 to 12 percent based on the total weight of the composition, of at least one polymer from high pressure ethylene. Preferably, the actual or measured inward flange value of the ethylene polymer extrusion composition of the invention will be at least 12 percent, preferably at least 16 percent, more preferably at least 24 percent, percent, most preferably 30 percent less than the expected inward flange value based on the contributions of the weight fractions of the component polymer compositions. The density of the composition of the invention will be in the range of 0.850 to 0.940 grams / cubic centimeter, preferably in the range 0.860 to 930 grams / cubic centimeter, more preferably in the range 0.870 to 920 grams / cubic centimeter, most preferably in the range 0.880 to 915 grams / cubic centimeter. The melt index, I2, of the composition of the invention will be in the range of 1 to 50 grams / 10 minutes, preferably in the range of 1 to 30 grams / 10 minutes, more preferably in the range of 1 to 20 grams / 10 minutes, most preferably in the range of 1.0 to 10 grams / 10 minutes. The strength of the melted product of the composition of the invention determined using a Gottfert Rheotens will be at least 9 centi-Newton (cN), preferably at least 15 cN, more preferably at least 20 cN, most preferably at least 25 cN. The term "polymer", as used herein, refers to a polymeric compound prepared by the polymerization of monomers, whether of the same or of a different type. The generic term "polymer" thus embraces the term "homopolymer" usually used to refer to polymers prepared from only one type of monomer. The term "interpolymer", as used herein, refers to polymers prepared by the polymerization of at least two different types of monomers. The generic term "interpolymer" thus includes the term "copolymers" which is used precisely to refer to polymers prepared from two different monomers. However, the term "copolymer" is also used in the art to refer to polymers prepared from two or more different monomers. The term "expected inward flange value" as used herein, as opposed to an actual, measured, inward flange value, refers to the expected or predicted inward flange value based on the calculations of the weight fractions and the individual inward flange values with which the component polymers of an extrusion composition contribute. As an example of the calculation, wherein an extrusion composition comprises 90 percent of an ethylene α-olefin interpolymer having a flange value in the extrusion coating of 1 thousand (0.026 millimeters) of 7.5 and 10 percent in weight of a high pressure ethylene polymer having a flange value inward of the extrusion coating in 1 mil (0.025 millimeters) of 1.75 inches (4.4 centimeters), the extrusion composition has an expected inward flanging value of 6.9 inches (17.5 centimeters) where 6.75 inches (16.9 centimeters) would be contribution of the ethylene polymer to -olefin and 0.175 inches (0.44 centimeters) would be contribution of the ethylene polymer to high pressure. The term "high pressure ethylene polymer" or "highly branched ethylene polyethylene" is defined herein to mean that the polymer is partially or totally homopo- polymerized or interpolymerized in autoclave or tubular reactors at pressures above 14,500 psi (100 MPa) with the use of free radical initiators The terms "homogeneous ethylene polymer" and "homogenously branched ethylene polymer" are used in the conventional sense with reference to an ethylene polymer in which the comonomer is randomly distributed within a polymer molecule given and where substantially all polymer molecules have the same ethylene for the molar proportion of comonomer.The homogeneously branched ethylene polymers are characterized by a short chain branching distribution index (SCBDI) greater than or equal to 30 percent, preferably greater than or equal to 50 percent, more preferably greater than or equal to 90 percent, and essentially lack a measurable high density (crystalline) polymer fraction. The short chain branching distribution index is defined as the weight percent of the polymer molecules having a comonomer content within 50 percent of the content of the median total molar comonomer. For polyolefins, the short chain branching distribution index and the presence of a high density polymer fraction can be determined by well-known techniques of elution fractionation by raising the temperature (IREF), as described by Wild et al. Journal of Polvmer Science. Poly. Phys. Ed. Vol. 20 p. 441 (1982), L.D. Cady, "The Role of Comonomer Type and Distribution in LLDPE Product Performance," SPE Regional Technical Conference, Quaker Square Hilton, Akron, Ohio, October 1-2, p. 107-119 (1985), or U.S. Patent No. 4,798,081.

The term "substantially linear ethylene polymer" includes the term "substantially linear α-olefin polymer". The substantially linear α-olefin polymers contain long chain branches as well as short chain branches attributable to the incorporation of the homogeneous comonomer. The long chain branches are of the same structure as the central structure of the polymer and are longer than short chain branches. The central structure of the substantially linear α-olefin polymer is replaced with an average of 0.01 to 3 long chain branches / 1000 carbon atoms. Preferred substantially linear linear polymers for use in the invention are substituted from 0.01 long chain branches / 1000 carbon atoms to 1 long chain branches / 1000 carbon atoms, and more preferably 0.05 long chain branches / 1000 carbon atoms to 1 long chain branches / 1000 carbon atoms. In specific embodiments, the polymer backbone of the substantially linear α-olefin polymer is replaced with at least about 0.1 long chain branches / 1000 carbon atoms or at least about 0.3 long chain branches / 1000 carbon atoms. Long chain branching is defined herein as a chain length of at least 6 carbon atoms, above which the length can not be distinguished using JC nuclear magnetic resonance spectroscopy. The long chain branching can be as long as about the same length as the length of the central structure of the polymer to which it is attached. The presence of long chain branching can be determined in the ethylene homopolymers using lJC nuclear magnetic resonance spectroscopy (NMR) and quantified using the method described by Randall (Rev. Macromol. Chem. Phys. C29, V. 2dc3, p. 285-297). Conventionally, current JC nuclear magnetic resonance spectroscopy can not determine the length of a long chain branch that exceeds 6 carbon atoms. However, there are other known techniques useful for determining the presence of long chain branches in ethylene polymers, including ethylene / l-octane interpolymers. Two of these methods are gel permeation chromatography coupled with a low-angle laser light scattering detector (GPC-LALLS) and gel permeation chromatography coupled with a differential viscometer detector (GPC-DV). The use of these techniques for the detection of long chain branches and the underlying theories have been well documented in the literature. See, for example, Zimm, G.H. and Stockmayer, W.H., J. Chem. Phys., 17,1301 (1949) and Rudin, A., Modern Methods of Polymer Characterization, John Wiley & Sons, New York (1991 pp. 103-112 A. Willem deGroot and P. Steve Chum, both of the Dow Chemical Company, on October 4, 1994, at the conference of the Federation of Analytical Chemistry and Spectroscopy Society (FACSS ) in St. Louis, Missouri, presented data demonstrating that GPC-DV is a useful technique for quantifying the presence of long-chain branches in substantially linear ethylene interpolymers, in particular, deGroot and Chum found that the level of the branching Long chain in the substantially linear ethylene homopolymer samples measured using the Zimm-Stockmayer equation correlates well with the level of measured ramifications using 13C nuclear magnetic resonance spectroscopy In addition, deGroot and Chum found that the presence of octene does not change the hydrodynamic volume of the polyethylene samples in solution and, as such, one can count on the molecular weight increase attributable to the branching Short chain ions of octene knowing the mole percentage of octene in the sample. Deconvolution of the contribution to the molecular weight increase attributable to the short chain branches of l-octene, deGroot and Chum showed that GPC-DV can be used to quantify the level of long chain branches in substantially linear ethylene / octene copolymers. Also deGroot and Chum demonstrated that a Log plot (I2, melt index) as a function of the Log (GPC Weight average molecular weight) determined by GPC-DV illustrates that aspects of long-chain branching (but not the extension of the long branching) of the substantially linear ethylene polymers can be compared to those of high pressure, highly branched low density polyethylene (LDPE) and are clearly distinguished from the ethylene polymers produced using Ziegler type catalysts such as titanium complexes and ordinary homogeneous catalysts such as hafnium and vanadium complexes. For the ethylene / α-olefin interpolymers, the long chain branching is longer than the short chain branching resulting from the incorporation of the α-olefins into the polymer backbone. The empirical effect of the presence of long chain branching on the substantially linear ethylene / α-olefin interpolymers used in the invention manifests itself, for example as increased rheological properties which are quantified and expressed herein in terms of rheometry results of Gas extrusion (GER) and / or increases in the flow of molten product, IJQ / 12- In contrast to the term "substantially linear ethylene polymer", the term "linear ethylene polymer" means that the polymer lacks chain branching long measurable or demonstrable. The molecular architecture of the high pressure ethylene polymer composition is critical with respect to inward flanging, the strength of the molten product and improvements in the processability of the final composition. The high pressure ethylene polymer for use in the invention has a relatively high melt strength, that is, at least 9 cN, preferably at least 15 cN, more preferably at least 20 cN, most preferably at least 25 cN . The high pressure ethylene polymer will also be characterized as having a bimodal distribution determined by gel permeation chromatography and a M ^ MJJ ratio of at least 7.0, preferably at least 7.3, more preferably at least 7.6. The melt index, I2, of the high pressure ethylene polymer that is used to prepare the extrusion composition of the invention is less than 6.0 grams / 10 minutes, preferably less than 1.0 grams / 10 minutes, more preferably at least 0.8 and most preferably less than 0.5 grams / 10 minutes. The density of the high pressure ethylene polymer composition for use in the invention is at least 916 grams / cubic centimeter, preferably at least 0.917, more preferably at least 0.918 grams / cubic centimeter. The density of the high pressure ethylene polymer composition will be higher when an interpolymer (e.g., copolymer or terpolymer) is used such as, for example, carbon monoxide-ethylene-vinyl acetate copolymer (EVACO) as the polymer component of the mixture. The high pressure ethylene polymer composition selected to be mixed with the ethylene / α-olefin interpolymer composition can be produced using conventional high pressure polymerization techniques in an autoclave or tubular reactor using at least one free radical initiator. When an autoclave reactor is employed, the reaction zone d may be a single zone or a multiple zone. Telogens, such as, for example, propylene and isobutane, can also be used as chain transfer agents. Preferably the high pressure ethylene polymer is produced using an autoclave reactor without adding a telogen due to the difficulty of manufacturing molecular weight distributions in a tubular process. Nevertheless, it is also convenient to combine an autoclave reactor in series or in parallel with a tubular reactor to make the composition of the invention since the bimodal molecular weight distributions can be manufactured using those techniques. Free initiators suitable for polymerizing ethylene at high reactor pressures are well known and include, but are not limited to, peroxides and oxygen. Techniques for maximizing the strength of the molten product of the ethylene polymers produced by high pressure polymerization are also well known and include, but are not limited to, maximizing the temperature differential of the reaction zone, multiple initiator injections, times of reactor residence and post-reactor and higher gas inlet temperature. Suitable high pressure ethylene polymer compositions for use in preparing the extrusion composition of the invention include low density polyethylene (homopolymer) and ethylene interpolymerized with at least one α, 0-ethylenically unsaturated comonomer, eg, acrylic acid , methacrylic acid, methyl acrylate and vinyl acetate. A convenient technique for preparing high pressure ethylene interpolymer compositions is described in McKinney et al. In U.S. Patent Number: 4,599,392. Although it is believed that both homopolymers and interpolymers are useful in the invention, homopolymer polyethylene is preferred. When at least one high pressure ethylene interpolymer composition is used, the preferred interpolymer composition will comprise from 0.1 to 55 weight percent comonomer, more preferably from 1 to 35 weight percent comonomer, and most preferably from 2 to 28 weight percent total, of comonomer, based on the total weight of the interpolymer composition. The substantially linear ethylene α-olefin polymers used in the present invention are a class of exclusive compounds that are also defined in U.S. Patent No. 5,272,236 and in U.S. Patent No. 5,278,272. The substantially linear ethylene polymers differ significantly from the class of polymers conventionally known as homogenously described branched linear ethylene / α-olefin copolymers, per. example, by Elston in U.S. Patent No. 3,645,992. The substantially linear ethylene polymers also differ significantly from the class of polymers conventionally known as heterogeneous Ziegler polymerized linear ethylene polymers (e.g., ultra-low density polyethylene, linear low density polyethylene or high density polyethylene made, for example, using the technique described by Anderson et al. in U.S. Patent No. 4,076,698 and used by Dohrer et al. as described in U.S. Patent No. 4,780,264) ', and of the class known as high-branched high-density low-density ethylene homopolymer and ethylene interpolymers, such as, for example, ethylene-acrylic acid (EAA) and ethylene-vinyl acetate (EVA) copolymers. Single-site polymerization catalysts (for example, the monocyclopentadienyl polymerization catalyst of the metal-olefin transition described by Canich in U.S. Patent Number: 5,026,798 or by Canich in U.S. Pat. No. 5,055,438) or restricted geometry catalysts (e.g., that described by Stevens et al. in U.S. Patent No. 5,064,802) can be used to prepare substantially linear ethylene polymers, while the catalysts are used with the methods described in U.S. Patent No. 5, 272, 236 and in the United States of America Patent No. 5,278,272. These polymerization methods are also described in PCT / US 92/08812 (filed October 15, 1992). However, substantially linear ethylene interpolymers and homopolymers are made, preferably using constrained geometry catalysts, especially restricted geometry catalysts such as those described in U.S. Patent Application Serial Numbers: 545,403, filed on July 3, 1990, 758,654, filed on September 12, 1991; 758,660, filed September 12, 1991; and 720,041 filed June 24, 1991. Suitable cocatalysts for use herein include, but are not limited to, for example, polymeric or oligomeric aluminoxanes, especially methyl aluminoxane or modified methyl aluminoxane (made, for example, as described). described in U.S. Patent No. 5,041,584, U.S. Patent No. 4,544,762, U.S. Patent No. 5,015,749, and / or U.S. Patent No. 5,041,585) as well as ion-forming, inert, compatible, non-coordinating compounds. Preferred cocatalysts are inert, non-coordinating boron compounds. The polymerization conditions for making the substantially linear ethylene interpolymer compositions used in the present invention are preferably those useful in the continuous solution polymerization process, although the application of the present invention is not limited thereto. Continuous polymerization processes in sludge or gas phase can also be used, provided that the polymerization conditions and suitable catalysts are used. To polymerize the substantially linear interpolymers and copolymers useful in the invention, single-site catalysts and restricted geometries can be used, but for substantially linear ethylene polymers, the polymerization process must be operated so as to form the polymers the substantially linear ethylene polymers. That is, not all polymerization conditions inherently make substantially linear ethylene polymers, even when the same catalysts are used. For example, in one embodiment of the polymerization process useful for making novel substantially linear ethylene polymers, a continuous process, as opposed to a batch process, is used. Preferably, for the substantially linear ethylene polymers, the polymerization is carried out in a continuous solution polymerization process. Generally, the manipulation of I? I2 while maintaining relatively low N / MJJ to produce the substantially linear ethylene polymers using the constrained geometry catalyst technology described herein is a function of reactor temperature and / or the ethylene concentration. The reduced ethylene concentration and higher temperature generally produces a high l / o2 / 2 ratio. Generally speaking, as the concentration of ethylene in the reactor decreases, the concentration of the polymer increases. For novel substantially linear ethylene interpolymers and homopolymers, the polymer concentration for a continuous solution polymerization process is preferably above about 5 weight percent of the reactor content, especially above about 6 weight percent of the reactor content. Generally, the polymerization temperature of the continuous process, using catalyst technology of restricted geometry, is from 20 ° C to 250 ° C. If a polymer with a narrower molecular weight distribution. { Hw / Mn from 1.5 to 2.5) having a ratio I ^ Q / 12 plus a ^ ta (for example, I? O / I2 of about 7 or more, preferably when less than about 8, especially, at least of about 9,) is desirable, the concentration of ethylene in the reactor preferably is not more than about 8 weight percent of the content of the reactor, and most especially, no more than about 4 weight percent of the content of the reactor. The substantially linear ethylene interpolymer compositions for use in the invention are characterized by having (a) a flow rate of the molten product, Il? / I2 - = - 5-63, (b) a molecular weight distribution, Mw / Mn > I10? 2 (c) a gas extrusion rheology such that the critical shear rate at the beginning of the fracture of the surface melt for the substantially linear ethylene polymer is at least 50 percent greater than the shear rate critical at the beginning of the fracture of the surface melt product for the linear ethylene polymer, wherein the substantially linear ethylene polymer and the linear ethylene polymer comprise the same comonomer or comonomers, the linear ethylene polymer has an I2, and density within 10 percent of the substantially linear ethylene polymer and wherein the respective critical shear rates • of the substantially linear ethylene polymer and the linear ethylene polymer are measured at the same melting temperature using an extruder rheometer. gas, and (d) a single differential scanning calorimetry, DSC, melting peak between -30 and 150 ° C. The substantially linear ethylene interpolymers used in this invention essentially lack a measurable "high density" fraction measured by the TREF technique. The substantially linear ethylene interpolymer generally does not contain a polymer fraction with a degree of branching less than or equal to 2 methyl / 1000 carbon atoms. The "high density polymer fraction" can also be described as a polymer fraction with a degree of branching of less than about 2 methyl / 1000 carbon atoms. Among other benefits, the lack of a high density polymer fraction allows coating smoothness, impregnability, improved optical properties as well as improved flexibility and elasticity of the film coating. The determination of the critical shear rate and the deformation of the critical shear stress with respect to the melt fracture as well as other rheology properties, such as the "rheological processing index", is performed using a gas extrusion rheometer (GER) The gas extrusion rheometer is described by M. Shida, R.N. Shroff and L.V. Cancio in Polymer Engineering Science Vol. 17, No. 11, p. 770 (1977), and in "Rheometers for Molten Plastics" by John Dealy, published by Van Nostrand Reinhold Co. (1982) on pp. 99-97. Experiments with gas extrusion rheometer are performed at a temperature of 190 ° C, at nitrogen pressures between 250 to 5500 psig using a diameter of 0.754 millimeters, die L / D 20: 1 with an inlet angle of 180 °. For the substantially linear ethylene polymers described herein, the rheological processing index is the apparent viscosity (in kpoise) of a material measured by gas extrusion rheometer at an apparent shear deformation of 2.15 X 106 dynes / square centimeter. . The substantially linear ethylene polymers that are used in the invention are ethylene interpolymers having a rheological processing index in the range of 0.01 kpoise to 50 kpoise, preferably 15 kpoise or less. The substantially linear ethylene polymers used herein have a rheological processing index of less than or equal to 70 percent of the rheological processing index of a linear ethylene polymer (either a conventional Ziegler polymerized polymer or a uniformly branched polymer as that described by Elston in U.S. Patent No. 3,645,992) having an I2, Mw / Mn and density, each within ten percent of the substantially linear ethylene polymers. The rheological behavior of substantially linear ethylene polymers can also be characterized by Dow's rheological index (DRI), which expresses a "normalized relaxation time as the result of long-chain branching" (See, S. Lai and GW Knight ANTEC '93 Proceedings, INSITE ™ Technology Polvolefins (ITP) - New Rulesin the Structure / Rheology Relationship of Ethylene to-Olefin Copolymers, New Orleans, LA, May 1993). The rheological index values of Dow range from 0 so that they do not have any measurable long chain branching (for example, the Tafmer ™ products available from Mitsui Petrochemical Industries and the Exact products available from Exxon Chemical Company) up to approximately 15 and is independent of the melting index. In general, for low to medium pressure ethylene polymers (particularly at lower densities the Dow rheological index provides improved correlations to the elasticity of the molten product and high shear flow capacity relative to the correlations thereof with proportions For the substantially linear ethylene polymers useful in this invention, the Dow rheological index is preferably at least 0.1, and especially at least 0.5, and more especially at least 0.8. Dow can be calculated from the equation: DRI = (3652879 * tQl .00649 / tj0-l) / 10 where TQ is the characteristic relaxation time of the material and? g is the shear viscosity of the material. Both r0 and? G are the values that "best fit" the crossed equation, which is, ? /? Q = 1 / (1 + (T * TQ) ^ where n is the mechanical law index of the material and? and T are the measured viscosity and the shear rate, respectively. The determination of the baseline of the viscosity data and the shear rate are obtained using a rheometric mechanical spectrometer (RMS) -800) under a dynamic sweep mode of 0.1 to 100 radians / second at 190 ° C and a rheometer of gas extrusion at extrusion pressures from 1,000 psi to 5,000 psi (6.89 to 34.5 Mpa), which corresponds to a shear strain of 0.086 to 0.43 Mpa, using a diameter of 0.754 millimeters, a L / D 20: 1 die , at 190 ° C. The materials of the specific material can be made from 140 to 190 ° C as required to adjust variations of the melt index. A graph of apparent shear strain versus apparent shear rate is used to identify the fracture phenomena of the molten product and quantify the critical shear rate and the critical shear stress strain of the ethylene polymers. According to Ramamurthy in the Journal of Rheology. 30 (2), 337-357, 1986, above a certain critical flow rate, the irregularities of the extruded product observed can be broadly classified into two main types: fracture of the surface melt and fracture of the coarse melt. The fracture of the surface melt occurs under seemingly stable conditions and flow ranges in detail from the loss of brightness of the specular film to the more severe form of "shark skin". Here, it is determined using the gas extrusion rheometer mentioned, the beginning of the fracture of the surface melt product (OSMF) is characterized at the beginning of the loss of gloss of the extruded product at which the roughness can only be detected by an amplification. of 40x. The rate of critical shear stress at the beginning of the melt fracture for substantially linear ethylene interpolymers and homopolymers is at least 50 percent greater than the critical shear rate at the beginning of the fracture of the surface melt of a polymer. of linear ethylene having essentially the same melt index I and the same ratio of M ^ MJJ. The fracture of the coarse melt occurs under unstable extrusion flow conditions and varies in details from regular distortions (rough and smooth alternating, helical, etc.) to random. For commercial acceptability and maximum abuse of the properties of films, coatings and profiles, surface defects should be minimal, if not absent. The distortion of the critical shear stress at the beginning of the fracture of the coarse melt for the substantially linear ethylene polymer compositions used in the invention, especially those having a density > 0.910 grams / cubic centimeter, is greater than 4 X 10 dynes / square centimeter. The critical shear rate at the beginning of the surface melt fracture (OSMF) and the start of the coarse melt (OGMF) fracture will be used in the present based on changes in roughness and surface configurations of the extruded product, extruded by means of a gas extrusion rheometer. Preferably, in the present invention, the substantially linear ethylene polymer composition will be characterized by its critical shear rate regime, rather than by its critical shear stress strain. Substantially linear α-olefin polymers, like other homogenously branched ethylene α-olefin polymer compositions consisting of a single polymer component material, are characterized by a single DSC melting peak. The single melting peak is determined using a differential scanning calorimeter standardized with indium and deionized water. The method includes sample sizes of 5-7 milligrams, a "first heating" to approximately 140 ° C which is maintained for 4 minutes, a cooling of 10 ° / minute to -30 ° C which is maintained for 3 minutes, and heating at 10 ° C / minute to 140 ° C for the "second heating". The single melting peak is taken from the heat flow curve against the "second heating" temperature. The total heat of the polymer melt is calculated from the area under the curve.

For substantially linear ethylene polymer compositions having a density of 0.875 grams / cubic centimeter, the single melting peak may show, depending on the sensitivity of the equipment, a "shoulder" or a "hump" on the low melting side which constitutes less than 12 percent, typically, less than 9 percent, and more typically less than 6 percent of the total heat of fusion of the polymer. Such an artifact can be observed for other homogeneously branched polymers such as Exact ™ resins and is discerned on the basis of the single melting peak curve that varies monotonically along the melting region of the artifact. Such an artifact occurs within 34 ° C, typically within 27 ° C, and more typically within 20 ° C of the melting point of the single melting peak. The heat of fusion attributable to an artifact can be determined separately by the specific integration of its associated area under the curve of heat flow against temperature. The molecular weight distribution of the ethylene α-olefin interpolymer compositions and the high pressure ethylene polymer compositions are determined by gel permeation chromatography on a Waters 150 high temperature chromatographic unit, equipped with differential refractometer and three columns of mixed porosity. The columns are supplied by Polymer Laboratories and are commonly packaged with pore sizes of 103, 104, 105 and 106 Á. The solvent is 1, 2, 4-trichlorobenzene, from which 0.3 percent by weight solutions of samples for injection are prepared. The flow rate is 1.0 milliliters / minute, the operating temperature of the unit is 140 ° C and the size of the injection is 100 microliters. The determination of the molecular weight with respect to the central structure of the polymer is deduced using polystyrene standards of narrow molecular weight distribution (from Polymer Laboratories) together with their dilution volumes. The equivalent molecular weights of polyethylene are determined using appropriate Mark-Houwink coefficients for polyethylene and polystyrene (as described by Williams and Ward in Journal of Polymer Science, Polymer Letters, Vol. 6, p.621, 1968) to derive the following equation: ^ * polyethylene = a * '^ polystyrene' • In this equation, a = 0.4316 and b = 1.0. The weight average molecular weight, Mw = EwxMM :, where wj and Mj are the fraction of the weight and the molecular weight, respectively, of the i-th fraction that is elided from the GPC column of gel permeation chromatography. It is known that substantially linear ethylene polymers have excellent processability, despite having a relatively narrow molecular weight distribution (ie, the ratio Mv // Mn is typically less than 3.5, preferably less than 2.5, and more preferably less than 2) . Surprisingly, in view of the discoveries of Dohrer and Niemann (U.S. Patent Number: 4,780,264 and ANTEC Proceedincrs 1989. "Resistance to Draw Resonance of Linear Low Density Poliethylene Through Improved Resin Design", pages 28-30) and unlike of homogeneously branched and heterogeneously branched linear ethylene polymers, the melt flow ratio (ij0 / i2) of substantially linear ethylene polymers can be varied essentially independently of the molecular weight distribution, M ^ MJJ. Accordingly, the ethylene α-olefin interpolymer for use in preparing the extrusion composition of the invention is a substantially linear ethylene polymer. The substantially linear ethylene polymers are homogeneously branched ethylene polymers and are described in U.S. Patent Number: 5, 272.236 and in the Patent of the United States of North America Number: 5,278,272. Homogeneously branched substantially linear ethylene polymers are available from The Dow Chemical Company as Affinity ™ polyolefin plastomers, and as Engage ™ polyolefin elastomers. Homogeneously branched substantially linear ethylene polymers can be prepared by continuous solution polymerization, slurry, or gas phase polymerization of ethylene and one or more optional α-olefin comonomers in the presence of a constrained geometry catalyst, as described in European Patent Application 416,815-A. Preferably, a solution polymerization process is used to make the substantially linear ethylene interpolymer used in the present invention. Although their molecular architecture differs significantly from that of substantially linear ethylene polymer compositions, homogenously branched linear ethylene polymer compositions are also useful in this invention. Single-site polymerization catalysts (for example, the monocyte-pentadienyl transition metal olefin polymerization catalysts described by Canich in U.S. Patent Number: 5,026,798 or by Canich in U.S. Pat. from North America Number: 5,055,438) can be used to prepare homogenously branched linear ethylene polymer compositions. As exemplified in U.S. Patent No. 3,645,992 to Elston, homogenously branched linear ethylene polymer compositions can also be prepared in conventional polymerization processes using Ziegler-type catalysts such as, for example, zirconium and vanadium. Another example is provided in U.S. Patent Number: 5,218,071 to Tsutsui et al, which discloses the use of hafnium-based catalyst systems for the preparation of homogenously branched linear ethylene polymer blends. Homogeneously branched linear ethylene polymers are typically characterized by having a molecular weight distribution, M ^ and / Mjj, of about 2.

Commercial examples of homogeneously branched linear ethylene polymer compositions suitable in the invention include those sold by Mitsui Petrochemical Industries as Tafmer ™ resins and by Exxon Chemical Company as Exact ™ resins. The terms "heterogeneous ethylene polymer" and "heterogeneously branched ethylene polymer" mean that the ethylene polymer is characterized as a mixture of interpolymer molecules having different proportions of ethylene versus comonomer. The heterogeneously branched ethylene polymers are characterized by having a short chain branching distribution index (SCBDI) of less than about 30 percent. All known heterogeneously branched ethylene polymers are linear and have no demonstrable or measurable long chain branching. The heterogeneously branched linear ethylene polymers are available from The Dow Chemical Company as Dowlex ™ linear low density polyethylene and as Attane ™ ultra low density polyethylene resins. The heterogeneously branched linear ethylene polymers can be prepared by the continuous, batch or semi-batch solution polymerization, sludge or gas phase of the ethylene and one or more optional comonomers of α-olefin in the presence of a Ziegler Natta catalyst, as by the process described in the patent of the United States of North America Number: 4,076,698 of Anderson et al. Preferably, heterogeneously branched ethylene polymers are typically characterized by having molecular weight distributions, Mw / Mn, in the range of from 3.5 to 4.1. The homogenously branched and heterogeneously branched α-olefin interpolymer compositions useful in the invention are interpolymers of ethylene and at least one α-olefin. Suitable α-olefins are represented by the following formula: CH 2 = CHR where R is a hydrocarbyl radical having from one to twenty carbon atoms. The interpolymerization process can be a solution technique, mud or gas phase or combinations thereof. Suitable α-olefins for use as comonomers include l-propylene, l-butene, 1-isobutylene, 1-pentene, l-hexene, 4-methyl-1-pentene, 1-heptene and 1-octene, as well as other types of monomers such as styrene, halo or alkyl substituted styrenes, tetrafluoroethylene, vinyl benzocyclobutane, 1,4-hexadiene, 1,7-octadiene, and cycloalkenes, for example, cyclopentene, cyclohexene and cyclooctene. Preferably, the α-olefin will be 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, or mixtures thereof. More preferably, the α-olefin will be 1-hexene, 1-heptene, 1-octene, or mixtures thereof, such as coatings, profiles and films made with the resulting extrusion composition will have especially improved abuse properties where these α-olefins are Higher ones are used as comonomers. However, more preferably, the α-olefin will be 1-octene and the polymerization process will be a continuous solution process. The density of the ethylene α-olefin interpolymers, as measured according to ASTM D-792, for use in the present invention is generally in the range of 0.850 grams / cubic centimeters (g / cc) to 0.940 g / cc , preferably from 0.86 g / cc to 0.930 g / cc, more preferably from 0.870 g / cc to 0.920 g / cc, and more preferably, from 0.88 g / cc to 0.915 g / cc. The molecular weight of the ethylene polymers is conveniently indicated using an index measurement in accordance with ASTM D-1238, Condition 190C / 2.16 kilograms (kg), formerly known as "Condition E" and also known as I2. The melt index is inversely proportional to the molecular weight of the polymer. Thus, the higher the molecular weight, the lower the melting index, although the relationship is not linear. The melt index for the ethylene α-olefin interpolymers useful herein is generally from 1 gram / 10 minutes (g / 10 min.) To 50 g / 10 min., preferably from 1 g / 10 min. up to 30 g / 10 min., more preferably from 1 g / 10 min. up to 20 g / 10 min., more preferably from 1.0 g / 10 min., up to 10 g / 10 min. Other useful measurements for characterizing the molecular weight of the ethylene α-olefin interpolymer compositions involve the determination of melt indexes with higher weights, such as, for example, common ASTM D-1238, Condition 190C / 10 kg (formerly known as " Condition N "and also known as I ^ Q) •" The melt flow rate "is defined herein as the ratio of a determination of a higher melting index versus a lower weight determination, and for the values measured by melt index IJQ and l2, the proportion of the melt flow is conveniently designated as IIQ / I2. The proportion of IIQ I2 of the ethylene α-olefin interpolymer component is preferably at least about 5.63, and especially from about 5.63 to about 18, and more especially from 6 to 15. The ethylene polymer extrusion compositions of this invention are they can be prepared by any convenient means known in the art including rotary drying mix, weight feed, solvent mix, melt mix via compound extrusion or side arm, or the like as well as combinations thereof. Multiple reactor polymerization processes can also be used to make the at least one ethylene α-olefin interpolymers useful for preparing the ethylene polymer composition of the present invention. Examples of ethylene α-olefin interpolymerization techniques by convenient multiple reactor are those described in pending applications related to serial number 07 / 815,716 filed on December 30, 1991 and serial number 08 / 010,958 filed on January 29, 1993, and the Patent of the United States of North America Number: 3,914,342. The multiple reactors may be operated in series or in parallel or a combination thereof, with at least one homogeneous single site type catalyst or conventional heterogeneous Ziegler type used in at least one of the reactors or in both reactors. When a multiple reactor technique is used to make the ethylene α-olefin interpolymer component of the invention, the high pressure ethylene polymer component can be added by side arm extrusion or heavy feed equipment located downstream of the multiple reactors but directly connected to the primary manufacturing stream, or by subsequent incorporation in a different manufacturing unit or even in converter installations. The extrusion composition of the invention can also be blended with other polymer materials and can be used to prepare monolayer or multiple layer articles and structures, for example a sealant, adhesive or tie layer. The other polymer materials can be mixed with the composition of the invention to modify the processing, film strength, heat seal or adhesion characteristics. Both the high pressure ethylene polymer composition and the ethylene α-olefin composition can be used in a chemically and / or physically modified form to prepare the composition of the invention. These modifications can be carried out by any technique known as, for example, by ionomerization and insertion by extrusion. Also additives such as antioxidants (for example, hindered phenolics such as Irganox® 1010 or Irganox® 1076 supplied by Ciba Geigy), phosphites (for example, Irgafos® also supplied by Ciba Geigy), adhesion additives (for example, PIB) may be included. , Standostab PEPQ ™ (supplied by Sandoz), pigments, colorants and fillers in the ethylene polymer extrusion composition of the present invention, as long as they do not interfere with the high stretch and the substantially reduced inward flange discovered by the Applicants . The article made of or using the composition of the invention may also contain additives to increase antiblocking and coefficient or friction characteristics including, but not limited to, treated silicon dioxide, talc, calcium carbonate, and clay, as well as primary and secondary and substituted fatty acid amides, cooling roll release agents, silicone coatings, and the like. Other additives may also be added to increase the anti-clouding characteristics of, for example, transparent molding films, as described, for example in Niemann in U.S. Patent Number: 4,486,552. Still other additives, such as quaternary ammonium compounds alone or in combination with ethylene-acrylic acid copolymers or other functional polymers, can also be added to increase the antistatic characteristics of coatings, profiles and films of this invention and allow, for example, packaging or making electronically sensitive goods. The multilayer constructions comprising the composition of the invention can be prepared by any known means including co-extrusion, laminations and combinations thereof. Moreover, compositions of this invention can be employed in coextrusion operations where a larger stretch material is used to essentially "carry" one or more lower stretch materials. The ethylene polymer extrusion compositions of this invention, either monolayer or multi-layer construction, can be used to make extrusion coatings, extrusion profiles and extrusion molded films. When the composition of the invention is used for coating purposes or in multi-layer constructions, substrates or layers of adjacent material may be polar or non-polar including, for example, but not limited to, paper products, metals, ceramics, glass and various polymers, particularly other polyolefins, and combinations thereof. For extrusion profiling, various items can be manufactured including, but not limited to, refrigerator packaging, wire and cable sleeves, wire coating, medical tubing and water tubing. The extrusion molding film made of or with the composition of the invention can be used for food packaging and for industrial wrapping applications.

EXAMPLES The following examples illustrate some of the particular embodiments of the present invention, but the following should not be construed as limiting the invention to the particular embodiments shown. Also, practitioners of these techniques will appreciate that the maximum line speeds achievable with one type of extruder or coater will not necessarily be the same as the speeds achievable with others and, as such, the same equipment arrangement should be used to provide important comparisons and to appreciate the advantages discovered by the applicants. Determinations were made at 190 ° C using a Gottfert Rheotens and an Instron capillary rheometer. The capillary rheometer was aligned and placed on top of the Rheoten unit and a filament of molten polymer was fed to the Rheotens unit at a constant contact speed of 25.4 mm / min. The Instron was equipped with a standard capillarity die of 2.1 mm in diameter and 42 millimeters in length (20: 1 L / D) and the filament was provided to the cog wheels of the Rheotens unit by rotating at 10 millimeters / second . The distance between the exit of the capillary die of the Instron and the grip point of the Rheotens rolling wheels was 100 millimeters. The experiment to determine the melt tension started by accelerating the rolling wheels of the Rheotens unit to 2.4 millimeters / second squared, the Rheotens unit is capable of acceleration speeds from 0.12 to 120 millimeters / second squared. As the speed of the rolling wheels of the Rheoten increases with time the stretching force was recorded in centi-Newtons (cN) using the Linear Variable Offset Transducer (LVDT) in the Rheotens unit. The computerized data acquisition system of the Rheotens unit recorded the stretching force as a function of winding wheel speed. The actual value of the melt tension was taken from the plateau of the recorded stretching force. The filament fracture velocity was also recorded in millimeters / second as the melt tension fracture rate.

Examples of Invention 1-3 and Comparative Examples 4-15 Table 1 summarizes the polymer compositions used in an extrusion coating and evaluation of melt tension. Sample A and B were substantially linear ethylene / 1-octene interpolymers manufactured in accordance with the teachings provided by Lai et al. In U.S. Patent Nos. 5,278,236 and 5,278,272. Sample C was a homogenously branched linear ethylene / 1-hexene interpolymer supplied by Exxon Chemical Company under the trade designation of Exact ™ 3022. Samples D-I were all high pressure ethylene polymers manufactured by The Dow Chemical Company. Sample E was fabricated using conventional tubular reactor techniques. Samples D and F-I were manufactured using conventional autoclave reactor techniques. As an example of the polymerization requirements for preparing a high pressure ethylene polymer suitable for use in the present invention, Table 2 summarizes the polymerization conditions used to make Sample D. The reactor employed was a continuous autoclave reactor of 38 centimeters, 10: 1 L / D, constant agitation. The D-I samples all contained 200-300 parts per million of Irganox ™ 1010 antioxidant and Sample C contained (according to infrared analysis following solvent extraction of pressed film from the sample) 230 ppm of active antioxidant Irganox ™ 1076, both antioxidants were supplied by Ciba-Geigy Chemical Company.

TABLE 1 SLEP = substantially linear ethylene polymer prepared by interpolymerization of ethylene and 1-octene prepared in a continuous solution polymerization process using a restricted geometric catalyst system. HLEP = homogeneous linear ethylene polymer, Exact ™ 3022 supplied by Exxon Chemical company LDPE = high pressure low density polyethylene TABLE 2 TABLE 2, Continued Autoclave Reactor Conditions Type of Initiator Zone 1 50/50 TPO / TPA Mix Initiator concentration Zone l,% weight in Isopar "TllMvl C 20 Initiator feed rate Zone 1, lbs / hr (kg / hr) 17.5 (7.9) Type of Initiator Zone 2 50/50 TPO / TPA Mix Initiator concentration Zone 2,% weight in Isopar ™ C 20 Initiator feed rate Zone 2, lbs / hr (kg / hr) 14.8 (6.7) Type of Initiator Zone 3 100 percent TPA Initiator concentration Zone 3,% weight in Isopar ™ C 20 Initiator feed rate Zone 3, lbs / hr (kg / hr) 6.8 (3.1) Type of Initiator Zone 4 50/50 TPA / DTBP Mix Initiator Concentration Zone 4,% weight in Isopar ™ C. 20 16.8 (7.6) Initiator feed rate Zone 4, lbs / hr (kg / hr) Degassed High Pressure Level 40 Low Pressure Separator Level, percent by volume 7,406 (3,359) Production speed, lbs / hr (kg / hr) None Secondary process TPO = terbutyl peroctate; TPA = terbutyl peracetate; DTBP = diterbutyl peroxide Isopar ™ C is an isoparaffin hydrocarbon solvent with a boiling range of 95-108 ° C supplied by Exxon Chemical Company.

Figure 1 illustrates the molecular weight distribution (MWD) of Sample D as determined by gel permeation chromatography (GPC) was bimodal (ie, the polymer composition is characterized as having a distinct high molecular hump). Figure 2 shows that the samples G and l have bimodal molecular weight distribution, while the samples F and H do not have different bimodality. Table 1 indicates that Samples D and G had relatively high melting stress, broad molecular weight distributions, and bimodality, and as such these materials are considered suitable blend component compositions to impart improved extrusion properties. Table 3 summarizes the blend compositions that were prepared from the individual polymer compositions listed in Table 1. The blend compositions were prepared either by mixing the melt in a Haake torque mixer or by weight feed of the components directly in the primary extruder of the extrusion coating line according to the percentages by weight shown in Table 3.

TABLE 3 * Not an example of the present invention, provided only for comparison purposes.

TABLE 3, (SECOND CONTINUATION) * Not an example of the present invention, provided only for comparison purposes. Examples 1-3, 6, 8 and 13 and comparative examples 4, 5, 7, 11-12, and 14-16 were evaluated to see their high stretch performance in an extrusion coating line with a primary extruder with 8.9 centimeters in diameter with a 30: 1 L / D ratio, a secondary extruder with 6.4 cm in diameter with a ratio of 24: 1 L / D and a secondary extruder of 5.1 centimeters in diameter. A 76-centimeter coextrusion slot feeding block die was attached to the primary extruder and stacked to 69 centimeters with a 0.51 millimeter die gap and an air gap / stretch of 15.2 centimeters. The line was controlled by a microprocessor system that included cell feeding hoppers for speed checks and weight control of the coating. The extrusion line was also equipped with a matt finish, cooling roller cooled with glycol set at 57 ° F (14 ° C). The target extrusion temperature and the screwing speed for all examples of extrusion coating was 625 ° F (329 ° C) and 90 rpm, respectively, unless noted otherwise. However, Example 13 and Comparative Examples 14 and 18 were extrusion coated at an extrusion melting temperature of approximately 612 ° F (322 ° C). The melt extrudate or fabrics for all examples were continuously extracted over 50 pounds (23 kilograms) of brown paper. The evaluation involved systematically increased line / takeoff speed while maintaining a constant spin speed (90 rpm) until stretch resonance was observed or tissue breakage occurred. The line speed at which the emergence of stretch resonance (ie, the tissue began to oscillate) was observed initially or at which tissue breakage occurred, it was taken as the final or maximum speed of stretching. Stretch rate, inward flange measurement at a line speed of 440 fpm (134 mpm) for a thickness of 0.025 millimeters), extruder amperage, die pressure, expected inward flange performance, and percent inward flange less than expected for the examples is summarized in Table 4. The contribution of the inward flanging component for Samples D and E was taken by extrapolation from Figure 3, since these materials could not be coated by extrusion as polymer compositions of one component In-flange performance was taken from a linear mixing rule equation as exemplified above. TABLE 4 Dimensional irregularities are observed that initially occur or the fracture of instantaneous takeoff against tissue. * Not an example of the present invention, - provided for comparative purposes. ** Extrapolated inward flange value of Figure 3 based on the determination of the melt tension.

ND = Not determined. NA = not applicable. As can be seen from the data in Table 4, extrusion coating compositions comprising high pressure ethylene polymers characterized by having high melt tension and high bimodal molecular distribution allowed substantially reduced inward beading performance in relation to the unmodified ethylene aolefin interpolymer compositions. However, surprisingly, the in-flange performance of these compositions was also significantly lower than expected in the respective component materials. In another evaluation, the hot sealing, hot viscosity, adhesion and rip properties of Example 1 were determined and compared with various commercially available sealant extrusion coating resins. Two different multi-layer structures were used for hot sealing and hot viscosity determination. The structures are as follows: Structure A: Hostaphan ™ 2 DEF caliber 48 / 0.0125 mm Primacor ™ 4608 / Example Structure B: 30 pounds (13.6 kilograms) Machine-bleached brown paper-Grade brown paper / 0.02 mm Primacor 3460 / Wettable Aluminum Sheet Type A caliber 0.0035 / Example Hostaphan 2DEF is a polyester film supplied by Hoechst Diafoil and Primacor 4608 and 3460 resins and ethylene-acrylic acid interpolymers (EAA) supplied by The Dow Chemical Company. For adhesion determinations, 0.035 gauge wet type 1A aluminum foil and 50 gauge oriented polypropylene were laminated separately slipped into the coater while the Example was coated at 400 fpm (122 mpm). Adhesion was taken as resistance to delamination or separation and was qualitatively qualified from excellent to bad where an "excellent" rating denotes that the Example was highly resistant to separation when manually pulled. The tear properties were determined in accordance with ASTM D1922 and reported in grams. The tear resistance was measured both in the machine direction (MD) and in the transverse direction (CD) for the coated Example at 440 fpm (122 mpm) on 50 pound (23 kilogram) foil. The term "tear strength" is used here to represent the average between Elmendorf tear values of MD and CD and, likewise, is reported in grams. The hot stamp initiation temperature is defined as the minimum temperature for a seal strength of 2 pounds / inch (0.4 kg / cm). The hot seal test was carried out on a Topwave Hot Viscosity Tester using a drying time of 0.5 seconds with a seal bar pressure of 40 psi (0.28 MPa). Hot viscosity seals were made at increments of 5o in the range of 60-160 ° C by bending the sealing layer and sealing it on itself. The seals thus formed were pulled 24 hours after they were made using an Instron tensiometer at a crosshead speed of 10 inches / minute (51 centimeters per minute). The heat seal strength was taken as the maximum resistence in pounds per inch for the Example in a temperature range of 60 to 160 ° C before the sealing bar burns through the sealant layer. The hot viscosity initiation temperature is defined as the minimum sealing temperature required to develop a seal strength of 4 Newton / inch (1.6 N / centimeter). The hot viscosity test was performed using a Topwave Hot tack tester set at 0.5 seconds drying, 0.2 second delay time, and 40 psi (0.28 MPa) of seal bar pressure. The hot viscosity seals were made in increments of 5o in a temperature range of 60 to 160 ° C by bending the sealant layer above and sealing it with hot viscosity on itself. The peeling speed applied to the hot viscosity seals was 150 millimeters / second. The tester pulled the stamp immediately after 0.2 seconds of delay. The hot viscosity resistance was taken as the maximum value N / inch in the temperature range of 60-160 ° C for the Example. The hot viscosity window was taken as the temperature range where the resistance to hot viscosity was >; 4 Newtons for Structure A and > 8 Newtons for Structure B. Table 5 illustrates the comparative performance properties of Example l.

TABLE 5 E = excess, G = ueno, R = regu ar; P = ma or; D = or determined, CND = could not be determined since the viscosity resistance did not exceed 4 Newtons at any temperature. * It is not an example of the invention; provided for comparison purposes. Comparative Examples 17 and 18 are Dowlex 3010 and Primacor 3440, both of which are supplied by The Dow Chemical Company. Comparative example 19 is Surlyn ionomer 1652 which is supplied by Dupont Chemical Company.

Table 5 shows that Example 1 of the invention has excellent sealing properties, making it useful as a sealer layer in both single-layer and multi-layer constructions.

Claims (20)

1. An ethylene polymer extrusion composition comprising from about 75 to 95 percent, by weight of the total composition, of at least one ethylene / α-olefin interpolymer selected from the group consisting of a substantially linear ethylene polymer, a homogenously branched linear ethylene polymer and a heterogeneously branched linear ethylene polymer, wherein the ethylene / α-olefin polymer is characterized as having a density in the range of 0.85 grams / cubic centimeters to 0.940 grams / cubic centimeters and from about 5 to 25 percent, by weight of the total composition, of at least one high pressure ethylene polymer characterized by having a melt index, I2, less than 6.0 grams / 10 minutes, a density of at least 0.916 grams / centimeter cubic, a melt strength of at least 9 cN as determined using a Gottfert Rheotens unit at 190 ° C, a ratio of Mw / Mn of at least 7.0 and a molecular weight distribution determined by gel permeation chromatography, wherein the ethylene polymer extrusion composition has a melt index, I2, of at least 1.0 gram / 10 minutes. The composition of Claim 1, wherein the at least one ethylene α-olefin interpolymer is a substantially linear ethylene interpolymer characterized by having: (a) a melt flow rate, I o / I 2 'determined from according to ASTM D-1238, Condition 190C / 2.16 kg. and ASTM D-1238, Condition 190C / 10 kg., > 5.63, (b) a molecular weight distribution, ^ / MQ, determined by gel permeation chromatography and defined by the equation: ~ S-2 is determined in accordance with ASTM D-1238, Condition 190C / 2.16 kg. and ASTM D-1238, Condition 190C / 10 kg, (c) a gas extrusion rheology so that the critical shear rate at emergence of the surface melt fracture for the substantially linear ethylene polymer is at least 50 percent greater than the critical shear rate at emergence of the surface melt fracture for a linear ethylene polymer, wherein the substantially linear ethylene polymer and the linear ethylene polymer comprise the same comonomer or comonomers, the linear ethylene polymer has a I

2, Mw / Mn and density within ten percent of the substantially linear ethylene polymer and where the respective critical shear rates of the substantially linear ethylene polymer and the linear ethylene polymer are measured at the same melting temperature using a rheometer of gas extrusion, and (d) a single differential scanning calorimetry, DSC, melting peak between -30 and 150 ° C.

3. The composition of claim 2, wherein the substantially linear ethylene polymer has from 0.01 to 3 long chain branches / 1000 carbon atoms.

The composition of claim 3, wherein the substantially linear ethylene polymer has at least about 0.1 long chain branches / 1000 carbon atoms.

The composition of claim 4, wherein the substantially linear ethylene polymer has at least about 0.3 long chain branches / 1000 carbon atoms.

The composition of claim 1, wherein the α-olefin is at least one α-olefin of 3 to 22 carbon atoms.

The composition of claim 6, wherein the α-olefin is selected from the group consisting of propylene, 1-butene, 1-isobutylene, 1-hexene, 4-methyl-1-pentene, 1-pentene, 1-heptene and 1-octene.

The composition of claim 2, wherein the ethylene α-olefin interpolymer composition is in the range of 85 to 95 percent, based on the total weight of the composition, the high pressure ethylene polymer composition is in the range of 5 to 15 percent, based on the total weight of the composition, and the high pressure ethylene polymer composition is characterized by having a melt index, l2, less than 1.0 grams / 10 minutes, a density of at least 0.916 grams / cubic centimeter, a melt tension of at least 15 cN determined using a Gottfert Rheotens unit at 190 ° C, a ratio of N ^ / MQ of at least 7.3 and a bimodal molecular weight distribution determined by gel permeation chromatography.

The composition of claim 8, wherein the ethylene α-olefin interpolymer composition is a copolymer of ethylene and 1-octene and the high pressure ethylene polymer composition is an ethylene homopolymer.

The composition of claim 1, wherein the at least one ethylene α-olefin interpolymer composition is a homogenously branched linear ethylene polymer.

The composition of claim 1, wherein the at least one ethylene α-olefin interpolymer composition is a heterogeneously branched linear ethylene polymer.

The composition of claim 1, wherein the at least one high pressure ethylene interpolymer composition is an ethylene homopolymer.

The composition of claim 1, wherein the at least one high pressure ethylene polymer composition is an interpolymer of ethylene and at least one unsaturated comonomer.

A process for making an ethylene polymer extrusion composition comprising: (a) combining from 5 to 25 percent, by weight of the extrusion composition, of at least one high pressure ethylene polymer with 75 to 95 percent, by weight of the extrusion composition, of at least one ethylene α-olefin interpolymer, wherein at least the high pressure ethylene polymer is combined using addition equipment which is part of the polymerization process used to prepare the at least one ethylene α-olefin interpolymer, to prepare an ethylene polymer extrusion composition having a melt index, I 2, of at least 1.0 grams / 10 minutes and an inward flange of 1 thousand (0.025 millimeters) in an extrusion coating of a layer with a weight at least 12 percent lower than the expected value of inward flanging for the composition, and (b) collecting or transporting the extrusion composition. n in a form suitable for a subsequent use.

15. A process for using an ethylene polymer extrusion composition to make an extrusion coated substrate, an extrusion profile or an extrusion mold film comprising: (i) feeding an ethylene polymer composition within at least an extruder of an extrusion line, wherein the composition of the ethylene polymer comprises from 75 to 95 percent, by weight of the total composition, of at least one ethylene / olefin interpolymer selected from the group consisting of a composition of substantially linear ethylene polymer, a homogenously branched linear ethylene polymer composition and a heterogeneously branched linear ethylene polymer composition, wherein the ethylene / α-olefin polymer is characterized as having a density in the range of 0.85 grams / centimeter cubic at 0.940 grams / cubic centimeter and a melt index, I2, in the range of 0.1 to 50 grams / 10 minutes, and from 5 to 25 percent, by weight of the total composition, of at least one high pressure ethylene polymer, characterized by having a melt index, I2, of less than 1.0 gram / 10 minutes, a density of at least 0.916 grams / cubic centimeter, a melt strength of at least 9 cN determined using a Gottfert Rheotens unit at 190 ° C, a Kw / Ma ratio of at least 7.0 determined by gel permeation chromatography and a given bimodal molecular weight distribution by gel permeation chromatography, and wherein the extrusion composition of the ethylene polymer has a melt index, I2, of at least 1.0 gram / 10 minutes, (ii) melting and mixing the ethylene polymer composition to form when minus a stream of uniform molten polymer, (iii) operate the extrusion line at line speeds greater than 152 meters / minute, (iii) extrude the molten polymer stream through a die to form a primary extruded product, and either (a) stretch and cool the extrudate to prepare the extruded profile of at least one layer of the extrusion composition of the ethylene polymer, or (b) stretch the extrudate into the substrate to thereby coat the substrate with at least one layer of the extrusion composition of the ethylene polymer, or (c) stretching and cooling the extrudate in a take-off device to make the film with at least one layer of the ethylene polymer extrusion composition, and (vi) transporting or collecting the profile, the coated substrate or film for subsequent use.

The process of claim 15, wherein at least one layer of step (iii) (a), (iii) (b) or (iii) (c) is a sealer layer, adhesive layer or abuse resistance layer .

The process of claim 15, wherein at least one layer of step (iii) (b) is a sealant layer.

18. An article comprising at least one layer of an ethylene polymer extrusion composition, wherein the ethylene polymer extrusion composition comprises from 75 to 95 percent, by weight of the total composition, of at least one interpolymer ethylene / α-olefin, selected from the group consisting of a substantially linear ethylene polymer, a homogeneously branched linear ethylene polymer composition and a linearly heterogeneously branched ethylene polymer composition, wherein the ethylene / α-polymer olefin is characterized by having a density in the range of 0.85 grams / cubic centimeter to 0.940 grams / cubic centimeter and from 5 to 25 percent, by weight of the total composition, of at least one ethylene polymer at high pressure, characterized by have a melt index, I2, less than 6.0 grams / 10 minutes, a density of at least 0.916 grams / cubic centimeter, a product resistance molten at least 9 cN determined using a Gottfert Rheotens unit at 190 ° C, a Mw / Mn ratio of at least 7.0 determined by gel permeation chromatography and a bimodal molecular weight distribution determined by gel permeation chromatography, where The extrusion composition of the ethylene polymer has a melt index, I2, of at least 1.0 grams / 10 minutes.

19. The article of claim 18, wherein the ethylene polymer composition is in the form of an extrusion profile, an extrusion coating on a substrate or an extrusion molding film.

20. The article of claim 18, wherein the at least one layer of an ethylene polymer composition is a sealant layer, an adhesive layer or an abuse resistance layer.