MXPA00004895A - Ethylene polymer compositions with norbornene comonomer - Google Patents

Abstract

A composition comprising a metallocene catalysed ethylene/cyclic olefin polymer, particularly an ethylene/norbornene copolymer and an ethylene/norbornene/alpha olefin terpolymer resin, of improved toughness and processibility for film production. This invention provides ethylene based resins which are processible like an LLDPE but which are significantly improved with respect to their capability to be fabricated into a film layer, particularly by a blown bubble extrusion technique. Films prepared of the resins of this invention are significantly improved with respect to certain of their film properties, such as tear strength, without detracting from the beneficial properties that an LLDPE-like resin otherwise provides to a film. Molding application of the above E/NB copolymers and E/NB/O terpolymers is also disclosed.

Description

COMPOSITIONS OF ETHYLENE POLYMER WITH NORBORNEN CO-MONOMER BACKGROUND OF THE INVENTION Polyolefins and other types of polymers are typically manufactured in films by either of two general film forming techniques. The melted polymer can be forged by extrusion through a slot die to form a film layer, and the films thus formed are generally referred to as forged films. Or the melted polymer can be extruded through an annular die to form a gas-proof extruded housing which is then filled with blown air for expansion of the extrudate into a supported film bubble, and the films thus formed are generally referred to like blown bubble films. The technique of forming polymer resins in films by an insufflated bubble extrusion technique is widely practiced and presents various simplifications and processing conveniences compared to that of film forming by slot die extrusion forging techniques. However, in order to successfully implement film formation by an insufflated bubble extrusion technique, the polymeric resin from which the film layer is to be formed must possess certain minimum physical / mechanical properties, the principal one of which is a resistance to its extrusion temperature (ie, "melt strength") sufficient to withstand the formation of a film bubble during its inflation and expansion by air. Heretofore, certain types of polymeric resins that otherwise possess physical / mechanical / chemical properties that are desirable in a film for various end uses, have exhibited melt strength properties that make such resins problematic for film production by an insufflated bubble extrusion technique. A similar type of problematic polymer resin is that of linear low density polyethylenes. A linear low density polyethylene, conventionally referred to as LLDPE, is a copolymer of ethylene with a minor amount of an olefinic hydrocarbon co-monomer, typically an acyclic C3-C8 alpha-olefin, such that the ethylene comprises at least about 80 % by weight of the polymer while the content of acyclic alpha-olefin co-monomer is less than about 20% by weight of the polymer mass. The copolymerization of ethylene with such minor amounts of acyclic olefinic hydrocarbon co-monomer introduces short chain branching along the polymer backbone, to yield an ethylene-based thermoplastic polymer having a density in the range of about 0.910. at about 0.940 g / cm3, with lower densities associated with higher co-monomer contents and higher densities associated with lower comonomer contents. An LLDPE in this way possesses many attributes of mechanical / physical properties that are similar to a low density, highly branched polyethylene (LDPE) produced by free radical polymerization under high pressure, while an LLDPE also possesses certain mechanical / chemical and rheological properties such as those of an unbranched or linear high density homopolyethylene (HDPE) produced by low pressure Ziegler-Natta polymerization processes. Therefore, this type of ethylene-alpha-olefin thermoplastic copolymer, with high ethylene content, is referred to as a linear low density polyethylene, namely LLDPE. LLDPEs are used as such, or as a component in physical mixture with still other polymers, for the formation of films that are designed for a variety of applications, such as: films for the consumer product market, such as garbage bags Disposable, domestic and linings; Wrapping films and bags for laundry and dry cleaning items; and shipping and shopping bags for retail marketing. LLDPE is desirable as a resin for films of such end-use designs due to its relatively low cost compared to other types of resin, such as polyvinyl chloride, etc. It also has, in combination with its low cost, an excellent set of mechanical / physical / chemical properties such as tensile strength, secant modulus, tensile stress resistance, puncture resistance, elongation at break, etc. For this purpose, LLDPE resins have hitherto been extruded into film layers by both film forming techniques - slot die and bubble blow extrusion techniques. However, due to the relatively low melt strength and relatively low melt viscosity under low shear rates of an LLDPE resin compared to other types of polymer, an LLDPE is more difficult to use as such for manufacturing in a film layer by means of the blown bubble extrusion technique. Therefore, when an LLDPE resin is used as such in an insufflated bubble extrusion technique for film formation, the processing conditions must be controlled more carefully within a narrower window of operating conditions and certain conditions must be observed. limitations on the dimensions at which the film layer of an LLDPE can be produced, particularly its film thickness. Such limitations that must be observed with an LLDPE as used in an insufflated bubble extrusion technique for film formation further limit the rate of film production compared to that to which other types of film polymer can be produced by a film-forming technique. blown bubble extrusion. SUMMARY OF THE INVENTION This invention provides resins of a high ethylene (E) content (77% by weight) and a co-monomer content, wherein a cyclic olefin, preferably norbornene (NB), is incorporated into at least one 0.1 mol%, which are significantly improved with respect to their ability to be manufactured in a film layer, particularly by means of an insufflated bubble extrusion technique. The high ethylene content polymers of this invention are substantially linear polymers as the polymer backbone contains substantially only short chain branching, and in this respect the ethylene polymers of this invention are similar to the linear polyethylenes (LPE) hitherto known; The ethylene polymers of this invention have many properties as an LLDPE while having densities that may be higher than those of an LLDPE, as is typically prepared with acyclic alpha-olefins as a co-monomer. The ethylene polymers of this invention may be a cyclic ethylene / olefin copolymer or an ethylene / cyclic olefin / acyclic alpha-olefin terpolymer. The cyclic olefin can be any cyclo-olefin including cyclicized ethylenic or acetylenic unsaturation which in the presence of a metallocene catalyst will be inserted into a polymer chain without ring opening, such that the ring structure in which the unsaturation is present is incorporated in the backbone of the polymer. Examples of suitable cyclic olefins are described in U.S. Patent No. 5,635,573, the disclosure of which is incorporated herein by reference. Preferred as the cyclic olefin are the norbornenes which include norbornene and norbornene substituted C ^ Q alkyl, cyclopentenes, and tetracyclododecene. Of these, the most preferred are the norbornenos. The ethylene polymers of this invention can be a cyclic ethylene / olefin copolymer, such as an ethylene / norbornene copolymer (E / NB), or an ethylene / cyclic olefin / acyclic alpha-olefin terpolymer, such as ethylene interpolymer / norbornene / acyclic alpha-olefin (E / NB / O). The most preferred thermoplastic ethylene polymers of this invention comprise an ethylene / norbornene copolymer (E / NB) having a norbornene content of 0.1-8 mol%. The norbornene co-monomer may be norbornene as such or a substituted C-30 alkyl norbornene having the alkyl substituent in the 5 or 7 position, preferably at position 5. Of the substituted norbornenes, C1_20 alkyls are preferred, and C1_10 alkyls are most preferred. Hereinafter, this kind of copolymer is generally referred to as an E / NB copolymer although when a substituted alkyl norbornene is employed, the copolymer can be referred to as an E / NB-R copolymer, where R denotes the alkyl substituent.

According to this invention, the E / NB copolymer is prepared by polymerizing ethylene with norbornene or a substituted alkyl norbornene using a metallocene catalyst supported in a batch or two phase continuous polymerization process, such as a gas phase process or a slurry process, to produce a copolymer or terpolymer of ethylene and norbornene having a heavy average molecular weight (Mw) of 20,000 to 300,000 or greater; a molecular weight distribution (Mw / Mn) of 2 to 5; a melt index (MI) of 0.1 to 100 degrees / minute, preferably 0.1 to 10 degrees / minute, as determined in accordance with test method ASTM D 1238, condition 190 / 2.16; and a broad distribution of said norbornene co-monomer (NB or NB-R) through the various molecular weight fractions comprising the ethylene / norbornene copolymer resin, as indicated by a value of the distribution amplitude index of co-monomer (CDBI) of at least 60%. The ethylene / norbornene copolymer (E / NB and / or E / NB-R) has a melt distribution, as determined by DSC, in the region of 60 to 135 'C, with a peak melting point the region of 120 to 135"C for norbornene co-monomer contents ranging from 0.1 to about 8 mol% Ethylene / norbornene copolymers (E / NB) exhibit many of the physical / mechanical properties of conventional LLDPEs , while also exhibiting a thinning behavior under shear stress so as to behave in its molten state as a fluid-like material Such ethylene and norbornene resins behave as LLDPE resins but are expected to have processing characteristics and considerably improved tenacity for the production of film layers, particularly for the production of film layers by an insufflated bubble extrusion technique, and thereby overcome the deficiencies in the processing capacity / toughness inherent in previous LLDPE resins for film production. Furthermore, it has been found that films prepared from the LLDPE type E / NB resins of this invention are considerably improved with respect to certain of their film properties, such as tear strength, without departing from the beneficial properties provided by a type of film. LLDPE resin to a film. Accordingly, the subject matter of this invention is the LLDPE resin type E / NB and the films produced therefrom, wherein at least one film layer thereof comprises the LLDPE resin type E / NB. It has further been found that the E / NB polymer can be prepared as a terpolymer where ethylene, a norbornene and an acyclic C3-C8 alpha-olefin are copolymerized to result in a LLDPE-type resin. In this case, on a molar basis, the amount of norbornene or substituted alkyl norbornene substituted is at least 0.1 mol%, but less than 10 mol%, preferably less than 7 mol%, and most preferably between 0.1 and 5 mol. % molar, while the amount of acyclic alpha-olefin incorporated is at least about 0.1 mol%, without exceeding about 10 mol%, preferably not exceeding about 7 mol%. Hereinafter, this class of terpolymers will generally be referred to as terpolymers of E / NB / O, regardless of whether or not the norbornene co-monomer is substituted alkyl. Such terpolymer types of E / NB / O of the LLDPE resins are generally of a density of at least about 0.910 g / cm 3, varying up to about 0.940 g / cm 3, and are further improved with respect to their processing capacity and characteristics of tenacity for film production. Films prepared from such terpolymer resins of E / NB / O exhibit a further improvement with respect to the tear strengths of films produced therefrom. Accordingly, the subject matter of this invention are the terpolymer types of E / NB / O of the LLDPE resins and films produced therefrom having at least one film layer comprising such a terpolymer resin of E / NB / O. Brief Description of the Drawings Figure 1 illustrates the sample configurations used for tear tests of the films described in the examples herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION This invention comprises, in its broadest aspects, ethylene polymers produced with metallocene, where a cyclic olefin is present as a co-monomer in an amount of or less than 10 mol% of the total monomer content of the polymer and where the polymer has a distribution of molecular weights of or less than 5 and an amplitude index of compositional distribution (CDBI) of or less than 60%. The ethylene polymer can be a copolymer of the cyclic olefin or a terpolymer of the cyclic olefin and an acyclic alpha-olefin. Norbornene is a preferred cyclic olefin for the production of these ethylene polymers as are the substituted alkyl norbornenes such as 5-methylnorbornene-2,5-ethylnorbornene-2,5-hexylnorbornene-2, and the like. This invention comprises an E / NB and E / NB / O type LLDPE resin that is easily processable and of sufficient toughness for efficient production in a film layer by an insufflated bubble extrusion technique. The ethylene / norbornene copolymer (E / NB) has a norbornene content which is less than 10 mol% and, preferably, from 0.1 to 8 mol% NB, while the terpolymer of E / NB / O has a content of norbornene less than 10 mol% and preferably from 0.1 to 5 mol%. It has been found that the production of an ethylene copolymer or ethylene terpolymer having a norbornene content (NB and / or NB-R) that is widely distributed through the different molecular weight fractions comprising the resin provides the resin characteristics of non-linear elongation. This provides the LLDPE resin type E / NB and E / NB / O melt strength and elasticity properties that allow rapid processing by bubble extrusion techniques blown into a bubble of excellent bubble stability film, which is susceptible to fast stretches. In addition, the films formed of LLDPE type E / NB and E / NB / O exhibit markedly superior tear resistance properties - with respect to strength both without notch and with notch to tear propagation - as compared to a comparable film formed of a conventional LLDPE. The catalyst for polymerization of the preferred E / NB and E / NB / O resins herein comprises a transition metal component having at least one ligand (L) which is a single ring or fused ring hydrocarbyl radical. which contains or comprises a cyclopentadienyl anion fraction through which the binding to the transition metal cation is linked in a coordinated manner. Such catalyst systems are now commonly referred to as "metallocene" catalysts (m) and many examples of such metallocene catalyst systems have now been described in the art. Metallocene catalysts, for example, are typically those bulky ligand transition metal complexes derivable from the formula:. { [LP) mM (A *) n] + k} h [B, - :)] 1 where L is a bulky ligand bound to M, p is the anionic charge of L and m is the number of ligands L and is 1, 2 or 3; A is a ligand linked to M and capable of inserting an olefin between the M-A bond, q is the anionic charge of A and n is the number of ligands A and n is 1, 2, 3 or 4; M is a metal, preferably a transition metal, and (pxm) + (qxn) + k corresponds to the formal oxidation state of the metal center, where k is the charge on the cation and k is 1, 2, 3 or 4; B 'is a non-nucleophilic, chemically stable anionic complex, preferably having a molecular diameter of 4 Angstrom or greater, and j is the anionic charge on B', h is the number of charge cations k, and i the number of charge anions j such that hxk = jx i. Any two ligands L and / or A may be bridged together. The catalyst compound may be complete sandwich compounds having two or more ligands L, which may be cyclopentadienyl ligands or substituted cyclopentadienyl ligands, or sandwich media having a ligand L, which is a cyclopentadienyl ligand or cyclopentadienyl ligand substituted with heteroatom or cyclopentadienyl ligand substituted hydrocarbyl such as an indenyl ligand, a benzindenyl ligand or a fluorenyl ligand and the like or any other ligand capable of? 5 linkage to a transition metal atom (M). One or more of these bulky ligands is p-linked to the transition metal atom. Each L can be substituted with a combination of substituents, which can be the same or different, including hydrogen or a straight, branched or cyclic alkyl, alkenyl or aryl radical, for example. The metal atom (M) can be a transition metal of group 4, 5 or ß, or a metal of the series of lanthanides and actinides. Preferably, the transition metal is a group 4 metal, particularly titanium, zirconium and hafnium in any formal oxidation state, preferably +4. Other ligands can be linked to the transition metal, such as a leaving group, such as but not limited to weak bases such as amines, phosphines, ether and the like. In addition to the transition metal, these ligands may optionally be linked to A or L. In one embodiment, the metallocene catalyst system used in this invention is formed from a catalyst compound represented by the general formula: (Lp) mM (A ° -) n (Er) 0 and an aluminum alkyl, alumoxane, alumoxane modified or any other organometallic compound containing oxy or non-coordinating ionic activators, or a combination thereof. Where L, M, A and p, m, q and n are as defined above, and E is an exiting anionic group, such as but not limited to hydrocarbyl, hydrogen, halide or any other anionic ligand; r is the anionic charge of E and o is the number of ligands E and o is 1, 2, 3 or 4, such that (p x m) + (q x n) + (r x o) is equal to the formal oxidation state of the metal center. Non-limiting examples of the metallocene catalyst components and metallocene catalyst systems are discussed, for example, in U.S. Patent Nos. 4,530,914; 4,805,561; 4,937,299; 5,124,418; 5,017,714; 5,057,475; 5, 064, 802; 5, 198, 401; 5,278,264; 5,278,119; 5,304,614; 5,324,800; 5,347,025; 5,350,723; 5,391,790; and 5,391,789, all of which are incorporated herein by reference in their entirety. Also, such components and catalyst systems are discussed in the disclosures of EP-A-0 591 756; EP-A-O 520 732; EP-A-O 578 838; EP-A-0 638 595; EP-A-O 420 436; WO 91/04257; WO 92/00333; WO 93/08221; WO 93/08199; WO 94/01471; WO 94/07928; WO 94/03506; and WO 95/07140, all of which are hereby incorporated by reference in their entirety. In addition, the use of metallocene-type catalysts for the production of cyclic olefin copolymers is described in U.S. Patent Nos. 5,241,025; 5,324,801; 5,502,124; 5,629,398 and 5,635,573, all of which are incorporated herein by reference in their entirety. In contrast to previously known catalyst systems for the polymerization of alpha-olefins, which utilize a transition metal component that does not have an organo ligand having a cyclopentadienyl anion moiety, now commonly referred to as conventional catalysts or Ziegler-Natta (ZN), the metallocene catalysts are essentially single-site catalysts, while ZN catalysts are almost invariably multi-site catalysts that produce a polymer resin having a wide variety of polymeric structures. Traditional Ziegler-Natta catalysts typically comprise a transition metal halide, such as titanium or vanadium halide, and an organometallic compound of a metal of group 1, 2 or 3, typically trialkylaluminum compounds, which serve as an activator for the halide of transition metal. Some Ziegler-Natta catalyst systems incorporate an internal electron donor that is complexed with alkylaluminum or transition metal. The transition metal halide can be supported on a magnesium compound or complexed with it. This active Ziegler-Natta catalyst can also be impregnated on an inorganic support such as silica or alumina. For the purposes of this patent description, chromium catalysts, for example, described in U.S. Patent No. 4,460,755, which is incorporated herein by reference, are also considered to be traditional Ziegler-Natta catalysts. For more details on traditional Ziegler-Natta catalysts, see, for example, US Pat. Nos. 3,687,920; 4,086,408; 4,376,191; 5,019,633; 4,482,687; 4,101,445; 4,560,671; 4,719,193; 4,755,495; and 5,070,055, all of which are incorporated herein by reference. In contrast, an ethylene copolymer produced by a metallocene catalyst is much more uniform with respect to the polymer structures comprising the resulting m-LLDPE polymer resin, particularly with respect to the disparity between its different molecular weight fractions, such as it is indicated by the Mw / Mn value, the molecular weight distribution, or the Mw / Mn value of the m-LLDPE polymer resins generally being < 3.0, and with respect to the distribution of alpha-olefin co-monomer among its fraction of different molecular weight, as indicated by a high value of the co-monomer distribution amplitude index (CDBI) of more than 50%, and generally much greater. The E / NB polymers produced from a homogeneous catalyst system having a single metallocene component have an extremely narrow distribution of the norbornene co-monomer - most polymer molecules, regardless of their particular molecular weight, will have approximately same or comparable content of the NB-co-monomer that is, the CDBI of such an E / NB copolymer is generally greater than 60%. However, for the purposes of this invention, it is desired to produce the LLDPE type E / NB and E / NB / O to have a broad compositional distribution of the NB co-monomer such that the CDBI of the resulting resin is less than 60% , preferably less than 50%, and most preferably less than 45%, and in the order of about 15 to about 40%; all provided that the LLDPE type E / NB and E / NB / O retain a relatively narrow molecular weight distribution (MWD) (Mw / Mn) of less than 5, preferably less than 4, more preferably of the order of about 2.3 to around 3.4. For this purpose, it has been found necessary to employ the metallocene catalyst system in a heterogeneous or supported form and to employ it in a two-phase polymerization process such as a slurry or gas phase polymerization process. One measure of the compositional distribution is the "Compositional Distribution Amplitude Index" ("CDBI"), as defined in U.S. Patent No. 5,382,630, which is incorporated herein by reference. The CDBI is defined as the weight percentage of the copolymer molecules having a co-monomer content within 50% of the total, average molar co-monomer content. The CDBI of a copolymer is readily determined using well-known techniques to isolate individual weight fractions from a sample of the copolymer. One such technique is the so-called Temperature Elevation Elution Fraction (TREF), as described in Wild et al., J. Poly. Sci., Poly. Phys. Ed., Vol. 20, p. 441 (1982) as well as in U.S. Patent No. 5,008,204, which are incorporated herein by reference. Additional details for determining the CDBI of a copolymer are known to those skilled in the art. See, for example, international application WO 93/03093, published February 18, 1993. With norbornene as such as the comonomer, the mE / NB type LLDPE polymers employed in the films of this invention preferably have the same CDBIs or less than 35%, and in a range of 15 to 30%; usually in the range of 15-25%, and most typically in the range of 20-25%. Where the norbornene co-monomer is a substituted alkyl norbornene, the LLDPE polymers m-E / NB-R type employed in the films of this invention preferably have a CDBI of the order of 30 to 55%. The E / NB / O terpolymers employed in films of this invention preferably have CDBIs of less than 50%. LLDPE Resins Copolymer Type E / NB The mE / NB type LLDPE which is the preferred resin has a melt index (MI) in the range of about 0.4 to about 100, preferably in the range of about 0.5 to 50 , and more preferably from 0.8 to 4.0 degrees / min, as determined in accordance with test method ASTM D 1238, condition 190 / 2.16. The MI range for the LLDPE type E / NB resin for film production via an insufflated bubble technique is preferably from about 0.8 to about 3.0 degrees / min.; For forged film production, the MI range of LLDPE resins type E / NB is preferably around 0.75 to 4.0 degrees / min, preferably 1 to 5.0 degrees / min, more preferably 1 to 4 degrees / min , as determined in accordance with test method ASTM D 1238, condition 190 / 2.16. The selection of the melt index for the LLDPE type E / NB resin will generally be driven by the type of extrusion process and the specific equipment in use, as well as the final use for the films and / or the subsequent use in conversion operations. . The ethylene / norbornene copolymer which is suitable for purposes of this invention can be prepared by copolymerizing ethylene and norbornene or a substituted alkyl norbornene in the presence of a catalyst system comprising an activated cyclopentadienyl transition metal compound, namely a metallocene catalyst system which is in a homogeneous or supported form. The ethylene / norbornene copolymer is substantially uniform with respect to its molecular weight distribution (MWD) and norbornene or alkyl norbornene substituted is incorporated in a measure from about 0.1 to about 10 mol%. Preferably, the ethylene / norbornene copolymer has a weight average molecular weight (Mw) of from about 20,000 to about 300,000, and more preferably from about 60,000 to about 300,000, and a molecular weight distribution (Mw / Mn). ) substantially less than about 5, more preferably from about 2.0 to about 4.0. The ethylene / norbornene copolymer is crystalline, as reflected by the presence of a well-defined melting point peak (Tm) by differential scanning calorimetry (DSC). The norbornene or a substituted alkyl norbornene may generally comprise from about 0.1 to about 10 mol% of the E / NB copolymer, but preferably comprises from about 1 to about 7 mol%. At lower rates of incorporation than about 0.1 mol%, norbornene does not substantially affect the properties of the ethylene-based copolymer. Conversely, at levels of incorporation greater than about 10 mol%, the E / NB copolymer will become too amorphous, or at the extreme behave much like an elastomeric polyolefin. In this way, the proportion of norbornene or substituted alkyl norbornene is essential to obtain an E / NB copolymer having the properties required for use in film formation of the resins of this invention. The norbornene monomer may contain other forms of norbornene, as is common in its routine production and storage. Preferred E / NB copolymers for use in the present invention have several properties that make them desirable. The E / NB copolymers generally have good toughness and optical clarity such as the higher ethylene, propylene and alpha-olefin homopolymers; but they also tend to have greater elasticity and recovery after elongation. However, the films of the E / NB copolymers also have excellent tenacity and tear properties. LLDPE Resins Terpolymer Type of E / NB / O A terpolymer of ethylene, norbornene (including substituted alkyl norbornenes) and a C3-C8 alpha-olefin is produced by a process similar to that of the LLDPE resin type E / NB copolymer. That is, a metallocene catalyst in a heterogeneous form supported in a two phase polymerization process, such as a slurry or gas phase polymerization process, is employed for production of the E / NB / O terpolymer. Again, this procedure produces a relatively narrow molecular weight distribution terpolymer (Mw / Mn) generally less than 5.0, and preferably less than 4.0, while the NB or NB-R monomer is distributed randomly among the different weight fractions. molecular structure comprising the resulting resin. The ethylene / norbornene / alpha-olefin terpolymers (E / NB / O) which are suitable for the purposes of this invention have, on a molar percentage basis, a total content of norbornene and alpha-olefin co-monomer of 10 molar% or less, a heavy average molecular weight (Mw) of from 20,000 to about 300,000, and preferably a combination of proportions of co-monomer and total co-monomer content so as to provide a density of more than 0.90 but less than about 0.955 g / cm3. The E / NB / O terpolymer will have a distribution of its NB or NB-R and O co-monomers through the molecular weight fractions of the resin, such that the CDBI of this terpolymer is less than 60% and typically it will be no greater than 55%, and preferably of the order of 50 to 20%. The alpha-olefins that can be used are any of the C3-C20 alpha-olefins that have hitherto been used for the production of conventional LLDPE resins.

Preferred alpha-olefins are C3-C8 olefins, such as propylene, butene-1, hexene-1,4-methyl-1-pentene and octene-1. A preferred combination and a preferred content of co-monomers are norbornene and hexene-1, where norbornene is incorporated into the terpolymer resin of E / NB / O to the extent of from about 0.1 to about 10 mol%, preferably from about 1.5 to about 5.0 mole% and hexene-1 is incorporated in a measure of at least about 1 mole% to the balance of a total co-monomer content of 10 mole%. Preferably, hexene-1 is incorporated in an amount from about 1.0 to about 5.0 mol% of the E / NB / O terpolymer. The terpolymer types of E / NB / O of the LLDPEs which are the preferred resins have an MI of about 0.5 to about 100, preferably from 0.8 to 50, as determined in accordance with test method ASTM D 1238, condition 190 / 2.16; where, for film production by an insufflated bubble technique, an MI of 0.8 to 3.0 degrees / min is preferred, while for forging film production, an MI of 0.75 to 4.0 degrees / min; for molding applications, the above terpolymer with MI greater than 3 degrees / min is preferred. Polymerization Methodology for Resin Production The polymerization methodology used to produce an E / NB copolymer or E / NB / O terpolymer, as used in this invention, can be practiced in the manner and with the metallocene catalysts referred to, disclosed and described in the following references: U.S. Patent Nos. 5,055,438; 5,057,475; 5,096,867; 5,? 7,714; 5,153,157; 5,198,401; 5,278,119; 5,324,801; 5,629,398; 5,635,573, or published European patent applications Nos. 129 368 and 277 004, all of which are incorporated herein by reference. Generally, the preferred catalyst systems employed in the preparation of the E / NB and E / NB / O resins, as used in this invention, may comprise a complex formed by mixing a metallocene component of transition metal of group 4. with an activating component. The catalyst system can be prepared by adding the required transition metal components and alumoxane, or a transition metal metallocene component cationically 'activated, previously, to an inert solvent in which olefin polymerization can be carried out by a slurry or bulk phase polymerization process or by which the catalyst can be continuously supplied to a gas phase polymerization process. The metallocene catalyst used in this invention is deposited on support materials known in the art, for example any porous support material such as inorganic chlorides and inorganic oxides, such as silica, alumina, magnesia, magnesium chloride, or any polymeric material , such as polyethylene and polystyrene divinyl benzene. A particularly preferred catalyst for the preparation of the E / NB copolymer and / or its E / NB / O terpolymers is a bis (1,3-butyl-methyl cyclopentadienyl) zirconium dichloride activated with methylalumoxane (MAO), supported on silica. Such a catalyst can be easily prepared by techniques that are now well known to those skilled in the art. For example, such a catalyst may be prepared by adding the desired amount of MAO as a 30 wt% solution in toluene to a clean, dry reactor, maintained under a small nitrogen pressure. Additional toluene may be added, as desired, and subsequently the required amount of metallocene in solution in toluene is added, and the ingredient is kept under stirring at an elevated temperature, for example 80 ° C, for a time of up to one hour. Subsequently, this metallocene-MAO solution can be added to silica under stirring until all the metallocene-MAO solution has been added and agitation with the silica continued for a while. Later, the solids can be separated from the solution and subjected to vacuum drying at an elevated temperature until a free flowing powder results, this being supported metallocene-MAO catalyst. Optimal results are generally obtained where the transition metal compound of group 4 is present in the polymerization diluent, in a concentration preferably of about 0.00001 to about 10.0 millimoles / liter of diluent and the activating component when a component is present ion in an amount to provide a molar ratio of activator component to transition metal of about 0.5: 1 to about 2: 1 or more, and in the case of the alumoxane activating component, the molar ratio of alumoxane to transition metal it can be as high as 20,000: 1 (as a ratio of Al to transition metal atom). Sufficient diluent is normally used so as to provide adequate heat transfer away from the catalyst components during the reaction and to allow good mixing. The ingredients of the catalyst, i.e., the transition metal, the alumoxane and / or the ionic activators, and the polymerization diluent, can be added to the reaction vessel quickly or slowly. The temperature maintained during contact of the catalyst components can vary widely, such as, for example, from -100 to +300 'C. Preferably, during catalyst formation, the reaction is maintained within a temperature of about 25 to 100 ° C, most preferably around 25 to around 70 'C. As noted above, this catalyst is placed on a support to result in the final catalyst system. In a preferred process for producing the E / NB copolymer, the catalyst system is used in the liquid phase (slurry, suspension or bulky phase, or combinations thereof), high pressure fluid phase, or gas phase. The liquid phase process comprises the steps of contacting ethylene and norbornene with the heterogeneous metallocene catalyst system in a suitable polymerization diluent and reacting said monomers in the presence of said catalyst system for a sufficient time and temperature to produce a E / NB copolymer of sufficient molecular weight. Possible conditions for ethylene copolymerization are those where ethylene is subjected to the reaction zone at pressures of about 0.019 to about 50,000 psi, and the reaction temperature is maintained at about -100 to about +300 ° C. . The reaction time may vary from about 10 seconds to about 6 hours. However, it is preferred to conduct the polymerization at a temperature of at least 40 ° C, and more preferably at a temperature of from about 50 to about 120 ° C for a time from 30 to about 60 minutes, under monomer conditions having about 0.1 to about 10 mole% of norbornene or substituted alkyl norbornene incorporated into the copolymer product A similar slurry process can be employed for the production of a terpolymer resin of E / NB / O; however, for an E / NB / O terpolymer, an appropriate amount of a C3-C20 alpha-olefin would be added to the monomer feed and the monomer conditions are preferably those which have an incorporation of about 0.1 to about of 10 mol% of norbornene or substituted alkyl norbornene and from about 0.1 to about 10 mol% of alpha-olefin within the product of the terpolymer. A process for polymerization for production of an E / NB copolymer is as follows: in a stirred tank reactor, a liquid solution of 2-norbornene (also called norbornene-2) is introduced. The supported, heterogeneous catalyst system is introduced via nozzles to the reaction medium, which is a vapor phase or a liquid phase. Gaseous ethylene feed is introduced either into the vapor phase of the reactor, or mixed into the liquid phase, as is well known in the art. The reactor contains a liquid phase, such as a hexane diluent, the liquid phase being substantially composed of 2-norbornene together with such gaseous ethylene which dissolves in the liquid phase, and the vapor phase contains vapors of all the monomers. The temperature and pressure of the reactor can be controlled via reflux of the refrigerant co-monomer (self-cooling), as well as by coils, liners, etc. Cooling. The rate or rate of polymerization is generally controlled by the polymerization conditions, especially by controlling the concentration of the catalyst. The ethylene and norbornene content of the polymer product are determined by the ratio of ethylene to norbornene and their reactivity ratios in the reactor, which are controlled by manipulating the relative feed rates of these components to the reactor. Similarly, an E / NB / O terpolymer can be produced, in which case the C3-C20 alpha-olefin can be added to the solution of 2-norbornene in the stirred tank reactor before introduction of the ethylene monomer feed. Additives and Resin Processing. Conventional additives, such as anti-oxidants, Irganox 1076 (a hindered phenol) or Weston 390 (phosphites), and the like, may be incorporated with the resin, in their typical amounts, as desired. With respect to the tear resistance properties of a film formed of the LLDPE type E / NB resin of this invention, where the E / NB copolymer resin is produced with norbornene as the co-monomer, at reaction temperatures around of 40-90 ° C in a reaction time of about 15-60 minutes, to incorporate from about 0.1 to about 10 mol% NB; the tensile strength with notch (NTTS) and the resistance to tearing Elmendorf of a film made of such resin are both increased, compared with an LLDPE resin composed of ethylene and 10% by weight of hexene, with density of 0.917 g / cm3, MWD of 2.13, MI of 1.0 and Tm of 120 'C. For E / NB copolymers, where the norbornene comonomer is a substituted alkyl norbornene (5-alkyl norbornene-2), which alkyl is methyl, ethyl or hexyl, the NTTS of its films exhibited substantial improvement compared to the same resin of LLDPE (10% by weight of hexene). For an E / NB / O terpolymer type LLDPE resin, the NTTS of a film is improved, and the Elmendorf tear strength is also substantially improved where the terpolymer is produced at a reaction temperature of 80 to 90 * C in a reaction time of 15-60 minutes to incorporate at least 0.3 mol% of NB and at least 0.3 mol% of alpha-olefin. Blown films produced with an annular die and air cooling and forged films using a slot die and a cooling roll for cooling are both acceptable techniques for making a film layer of the LLDPE resin type E / NB terpolymer copolymer. / NB / O according to the present invention. Additionally, various additives are also contemplated, including pigments, tackifiers, anti-static agents, anti-fogging agents, anti-oxidants or other additives, and may be included in the resins and / or films made therefrom. Multiple layer structures may be preferred in some applications. Such structures include, but are not limited to, co-extruded films, and laminated films. Laminated films may include not only one or more film layers based on the resins of the present invention, but also other film layers, including but not limited to polyester, polyamide, polypropylene, other polyethylenes, Saran®, ethylene vinyl alcohol, and similar. Rolling methods include extrusion lamination, adhesive lamination, thermal lamination, and the like. Certain polymeric compositions according to the invention will be particularly suitable for molding applications, for example injection molding and roto-molding. Preferred compositions contain about 0.1-2.0 mol% cyclic olefin (and exhibit melt indexes (MI) greater than 3.0). EXAMPLES Example 1 - Copolymerization of Ethylene / Norbornene Activation of Catalyst The metallocene catalyst was prepared from silica at 600 'C having a water content of 1.3% by weight (Davison 948 silica, available from WR Grace, Davison Chemical Division, Baltimore, Maryland, United States). This catalyst was prepared by mixing 850 pounds (386 kg) of silica with 340 pounds (154 kg) of a catalyst precursor. The catalyst precursor was prepared separately by mixing together 82 pounds (37 kg) of a 28% by weight solution of bis (l-methyl-3-n-butyl-cyclopentadienyl) zirconium dichloride in toluene with 1.060 pounds (481 kg) ) of a 30 wt% solution of methylalumoxane, available from Albermarle Corporation (Baton Rouge, Louisiana, United States). Additional 1,300 pounds (590 kg) of toluene were added and the mixture maintained at 80 'F (27' C) for one hour, after which 6 pounds (3 kg) of a surface modifying agent (Kemamine AS-) was added. 990, available from Witco Chemical Corporation, Houston, Texas, United States) and allowed to mix for one hour. Vacuum was applied and the catalyst was allowed to dry for 15 hours. Then it was dried at 175 ° F (79 ° C) in a free-flowing powder.The final weight of the catalyst was 1.216 pounds (552 kg) .The final catalyst had a zirconium loading of 0.40% and an aluminum charge of 12.5% Reactor Conditions Hexane was transferred to a clean, dry, two-liter autoclave reactor that was pre-baked at 150 ° C under N2. The reactor was stripped with a 50.8% by weight solution of triethyl aluminum (TEAL) in hexane. A solution of 80.7% by weight of norbornene in hexane was transferred to the reactor. Finally, ethylene was introduced under regulated pressure. The mixture was stirred until the solution was saturated with ethylene and equilibrated at the temperature selected for reaction. The pre-active catalyst powder was pressurized in the reactor. The temperature was controlled at the fixed reaction temperature by circulating cooling water at room temperature, circulating, through the jacket of the reactor, as needed. Ethylene was re-supplied to maintain a predetermined pressure and the reaction was monitored by ethylene admission. The reaction was suddenly quenched after a selected time. Table 1 below reports the conditions of each run in terms of the amounts of NB and ethylene used, the reaction temperature and running time, polymer yield and polymer properties.

Table 1 15 Example 2 - Production and Properties of Copolymer Film of E / NB In the following example, a series of thin films (3-5 thousandths of an inch thick) was prepared by compression molding of 200 psi at 180 ° C and determined Various properties of the resulting films The polymer resins used in the production of these films were: (A) ECD-103 (now called Exceed 350D60), which is an LLDPE of ethylene-hexene copolymer containing 10% by weight of hexene; ECD-103 is an LLDPE having a density of 0.917 g / cm3, a melt index (MI) of 1.05 degrees / min, a molecular weight distribution (Mw / Mn) of around 2.13, and a temperature of first point of fusion of 110 'C (by DSC analysis) - film A; (B) an E / NB or ethylene-norbornene copolymer prepared with a metallocene catalyst in a heterogeneous form supported by slurry polymerization, according to each reported E / NB run in Table 1 above com or Bl to Bll film The Irganox 1076 anti-oxidant in an amount of 0.5 g (1% by weight) was added to all the resins. All the thin film samples were tested for resistance to notch stress tear (NTTS-units: energy / thickness in lbs), Elmendorf tear strength (g / thousandth) and analyzed by DSC with respect to the melting point ( Tm), and crystallization peaks (Te). The results are given in Table 2 below.

Tear Resistance Two methods were used to determine the tear strength of films: the Elmendorf tear test and the "notched strip tear test". The traditional method is the Elmendorf test, but it was found to be deficient for testing high tear strength films and compression molded samples, so that a second method, called "notched stress tear resistance" (or NTTS), it was developed. The sample configurations used for the tear tests are shown in Figure 1, A being for Elmendorf and B for NTTS. In blown or forged films, the initial notch in the sample is made parallel to either the machine direction or the transverse direction. By convention, the test direction is defined as the axis with which the notch is aligned. At the beginning of the Elmendorf test, a sample tab is grasped in a fixed jaw while the other is grasped in a movable jaw attached to a pendulum. When the pendulum is released, it oscillates downward, carrying the movable grip with it, subjecting the sample to a complex tear-leg tear, absorbing energy in the meantime. The Elmendorf tear strength is reported as the force required to break the sample in g / thousandths. In the NTTS or notched strip test, a 0.5-inch-wide strip has a "notch" cut of 0.25 inches in it with a razor, perpendicular to its long axis, which may be parallel or perpendicular to the direction of the machine. The sample is grasped by fixed jaws 1.5 inches apart and subjected to strain deformation in an Instron tensile test machine at an elongation speed of 0.5 inches / minute. The tear strength (lbs) is reported as the energy (lb-in) required for the rupture of the sample, divided by its thickness (inches). The notched strip tear test (NTTS) has the additional advantage that the zone of deformation can be observed directly during the course of the test.

Table 2 15 20 25 Example 3 - Production of Ethylene Copolymer / 5-Alkyl Norbornene-2 Activation of Catalyst An activated catalyst was prepared as in Example 1 and used for three polymerization runs, as reported in Table 3 below as "EX- 370". A second activated catalyst was prepared as in Example 1, with the same molar amounts of catalyst components, except that the transition metal compound used for the production of the catalyst was dimethylsilyl-bis (indenyl) zirconium dichloride. This catalyst was used for three polymerization runs, as reported later in Table 3 as "Zr-SS". Reactor Conditions The copolymerization was carried out as in Example 1, except that instead of norbornene-2,5-methyl norbornene-2, or 5-ethyl norbornene-2, or 5-hexyl norbornene-2, they were used as comonomer in amounts and under conditions as reported in Table 3 below.

Table 3 Example 4 - Production and Properties of Copolymer Film of E / NB-R Films of the copolymer resins of E / NB-R, as reported in Table 3 above as runs B12 to B17, were prepared in films in a manner similar to Example 2 and tested in a similar manner. Table 4 below reports the properties of the E / NB-R copolymer films. Table 4 FILM SAMPLE E / NB Example 5 - Production of Ethylene Terpolymer / Norbornene / Hexene Activation of Catalyst An activated catalyst was prepared as in Example 1. Reactor Conditions The reaction was carried out as in Example 1, except that an amount of hexene was added. -1 to the norbornene solution in the reactor before the introduction of ethylene. Table 5 below reports the condition of each run.

Table 5 Example 6 - Production and Properties of E / NB / O Terpolymer Film Films of E / NB / O terpolymer resins, as reported in Table 5 above as runs B18 and B19, were prepared in films in a manner similar to Example 2 and tested in a similar manner. Table 6 below reports the properties of the E / NB / O terpolymer films. Table 6 ' Example 7 - Production of Ethylene / Norbornene / Hexene Terpolymer Activation of Catalyst An activated catalyst was prepared as in Example 1. Reactor Conditions In this example, a gas phase polymerization reaction was used. A gaseous phase, fluidized bed, continuous run reactor [inner diameter of 16.25 inches (41.27 cm)] was used with the activated catalyst, supported, as described. In this procedure, norbornene was dissolved in the hexene co-monomer and this solution was supplied to the low pressure gas phase reactor in the amounts and under the conditions indicated below in Table 7, until a stable state was achieved. The injection of norbornene / hexene solution into the reactor served to vaporize the solution. In steady state for all runs, the reaction temperature was maintained at 75-80 ° C and the reaction pressure was maintained at 300 psi. The polymeric properties reported in Table 7 below are for those polymeric compositions recovered after achieving steady-state operation.

Table 7 Example 8 - Production and Properties of Terpolymer Film of E / NB / O Films of terpolymer resins of E / NB / O, as reported in Table 7 above as runs B21 and B25, were prepared in films in a manner similar to Example 2 and tested in a similar manner. Table 8 below reports the properties of the E / NB / O terpolymer films. Table 8 MOVIE SIGNATURE E / NB / O Example 9 - Production of Ethylene / Norbornene Terpolymer / Hexeno Activation of Catalyst An activated catalyst was prepared as in Example 1. Reactor Conditions Three terpolymer resins of E / NB / O were prepared as in Example 7. Table 9 below reports the conditions of each run. Table 9 Example 10 - Production and Properties of Molded Terpolymer Parts of E / NB / O Based on their NB content, MI and DSC data, samples of different loads were combined and physically mixed with a standard additive package (Irganox, 1,500 ppm + Weston, 1,500 ppm). These physical mixtures were molded under compression at 150 ° C and test samples were cut after 48 hours of equilibrium at room temperature.The flexural modulus was measured according to the ASTM method 749. The results are reported in Table 10. Table 10 Although this invention has been described by reference to its preferred embodiments, upon reading this disclosure, those skilled in the art will appreciate changes and modifications that can be made that do not deviate from the scope and spirit of this invention, as described before or as claimed later.

Claims (16)

1. 5th CLAIMS 1. A composition, comprising a product of polymerizing ethylene and a cyclic olefin in the presence of a metallocene catalyst in heterogeneous form to yield a substantially linear ethylene copolymer having an ethylene content of or greater than 77% by weight and an incorporated cyclic olefin content of 0.1 to 10 mole%, a molecular weight distribution of less than 5.0, a heavy average molecular weight of at least 20,000, and a CDBI of less than 60%. The composition of claim 1, wherein said ethylene copolymer has a melt distribution as determined by DSC in the region of 60 to 135"C. 3. The composition of claim 1 or 2, wherein said copolymer of ethylene has a CDBI of or less than 30% and a peak melting point temperature (Tm) in the range of 120 to 135 ° C. 4. The composition of any one of claims 1 to 3, wherein said cyclic olefin is norbornene. or a substituted alkyl norbornene 5. The composition of claim 4, wherein said cyclic olefin is a substituted alkyl norbornene C_10 6. The composition of claim 4, wherein said cyclic olefin is norbornene and said ethylene copolymer has a content of norbornene incorporated from 1 to 7 mole% 7. The composition of any one of claims 1 to 6, wherein said ethylene copolymer has an MI of 0.1 to 100 degrees / minute 8. The composition of any of the claims 1 to 7, wherein said ethylene copolymer has a MWD of 2.0 to 4.0. The composition of any of claims 1 to 8, wherein said ethylene copolymer is further a product of polymerizing cyclic ethylene and olefin in the presence of a C3-C20 alpha-olefin and said heterogeneous metallocene catalyst to yield a substantially linear terpolymer having an incorporated alpha-olefin and cyclic olefin content that together give a total of less than 10 mol% and said ethylene terpolymer has a heavy average molecular weight of at least 20,000. 10. The composition of claim 9, wherein said terpolymer has a density of or less than 0.955 g / cm3. The composition of claim 9 to 10, wherein said terpolymer has an MWD of 5.0 or less. The composition of any of claims 9 to 11, wherein said terpolymer has an incorporated alpha olefin content of 0.1 mol% or greater. The composition of any of claims 9 to 12, wherein said alpha-olefin is hexene-1. 14. A process for producing a composition according to any of claims 1 to 13, wherein ethylene and cyclic olefin are polymerized in the presence of a metallocene catalyst in heterogeneous form. A film, comprising a film layer composed of a composition according to any of claims 1 to 13. 16. A molded part, comprising a molded part layer composed of a composition according to any of the claims ia 13.