MXPA98001736A - A process to polymerize olefi - Google Patents

Abstract

An ethylene and a high molecular weight alpha-olefin copolymer having a window for the processing of the expanded melt and the fracture in the reduced melt can be produced using a catalyst system containing chromo and a trialkyl boron cocatalyst. The polymerization process must be carefully controlled to produce a copolymer resin that can easily be converted into manufactured goods.

Description

A PROCESS TO POLYMERIZE OLEFINS P BACKGROUND This invention relates to the copolymerization of a mono-1-olefin monomer, such as ethylene, with a high weight alpha-olefin comonomer molecular. It is well known that mono-1-olefins, such as ethylene, can be polymerized with catalysts that use vanadium, chromium or other metals in supports such as alumina, silica, aluminophosphate, titania, zirconia, magnesia and other refractory metals. Initially, such catalyst systems were used primarily to form ethylene homopolymers. This developed little, without However, the comonomers such as propylene, 1-butene, 1-hexene or other majors, the mono-1-olefins were copolymerized with ethylene to provide custom-made resins for end users specific. Frequently, high molecular weight and / or high density copolymers can be used for blow molding applications and the process of REF .: 26978 a product molded de'seádo. Unfortunately, these Copolymers are often plagued by various types of roughness on the surface as a result of a desire to increase the speed of processing. This roughness on the surface has been vaguely described in the past as having "instabilities due to fracture in fusion" or "channels". The channels or instabilities due to fracture in the fusion, can generally defined as irregularities and instabilities, such as anomalous, ridge-like structures that are formed during the melting process and are clearly seen within a different smooth, blow molded article. The channels may occur fortuitously and intermittently on any surface of the exterior or interior of the molded article and causes separation from the surface, causing unacceptable contamination of the contents or even structural degradation of the molded article. Generally, melt fracture instabilities are observed only in the interior of the molded article because die heat, or mold, can cause the outer surface of the molded article to be smoothed. The variation in the tangential velocities (R.P.M. of the extruder screw) for each type of copolymer can affect the instabilities due to fracture in the fusion. At low tangential speeds the extrudate may have a shark skin type or, matte, the polish that is characterized by irregularities of fine scales on the extruded surface. Even at high cutting speeds, the slip of the rod, the jet, or cyclic melting fracture can be observed. At the point of rod slip, the pressure in the extruder periodically oscillates between high and low pressure. The channels are formed and can always be seen at a point of the slip of the rod of an extrusion process, defined here as the critical tangential velocity. Finally, as the screw speed is further increased, the copolymer can enter a period of continuous slippage. Another way to describe the critical tangential velocity is the total velocity over the cross section of a channel in which polymer layers melt are slipped along * of each or along the wall in laminar flow. More operations to process the polymer occur in a limited window of extrusion (cutting), or production, speeds. Obviously, one method to avoid instabilities due to fracture in the fusion is to limit, for example, decrease production speeds and use very slow extrusion speeds. Thus, an improved polymer is one that does not exhibit instabilities due to the melting fracture at high tangential speeds, for example, which has a high critical tangential velocity. However, it is possible to increase the critical tangential velocity by increasing the melt index of the polymer and / or In order to decrease the molecular weight distribution of the polymer, other properties of the polymer can be adversely affected. Therefore, it is very desirable to produce a polymer where there is no instability due to fracture in the melt, For example, a polymer that has high critical tangential velocities. In addition, increasing the speed of polymer production in articles for manufacturing that minimize instabilities due to melt fracture has efficient use of polymer produced and processing equipment.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides an improved olefin polymerization process. The invention also provides a process for producing ethylene and mono-1-olefin copolymers which can be processed to increase production speeds and which increases critical tangential speeds, and / or a window for processing the melt. widened. The invention also provides a process for producing ethylene and mono-1-olefin copolymers having increased critical tangential velocities without the loss of other physical properties of the Polymer, and / or that can be processed at a high production rate in articles of manufacture.

In accordance with this invention, a polymerization process related thereto is provided: a) ethylene monomer; b) at least one mono-1-olefin comonomer having from about 2 to about 8 carbon atoms per molecule; c) a catalyst system comprising chrome supported on a silica-titania support, wherein said support comprises less than about 5 percent of titanium, based on the weight of the support, and where said catalyst system has been activated at a temperature within the range of about 900 ° F. to about 1050 ° F.; and d) a trialkyl boron compound, wherein said ratio occurs in a reaction zone in the absence of hydrogen, at a temperature within the range of about 180 ° F. at about 215 ° F., and recovering an ethylene / mono-1-olefin copolymer. According to another embodiment of this invention, a copolymer comprises ethylene and a mono-1-olefin having from about 3 to about 8 carbon atoms per molecule, wherein said copolymer has a density within the range of about 0.935. g / cc to about 0.96 g / cc; a high material melting index (HLMI) with a range of about 0.5 g / 10 minutes 5 to about 30 g / 10 minutes; and a critical tangential velocity for an onset of the fracture by the fusion of the sliding rod of greater or equal to about In accordance with this invention, a polymerization process is provided here which consists essentially of relating: a) ethylene monomer; b) at least one mono-1-olefin comonomer having from about 2 to about 8 carbon atoms per molecule; c) a catalyst system comprising chrome supported on a silica-titania support, wherein said support comprises less than about 5 percent of titanium, based on the weight of the support, and where said catalyst system has been activated at a temperature within the range of about 900 ° F. to d) a trialkyl boron compound, wherein said ratio occurs in a reaction zone in the absence of hydrogen, at a temperature within the range of about 180 ° F. to about 215 ° F., and recover an ethylene copolymer. According to another embodiment of this invention, there is provided a copolymer consisting essentially of ethylene and a mono-1-olefin having from about 3 to about 8 carbon atoms per molecule, wherein said copolymer has a density within the range about 0.935 g / cc to about 0.96 g / cc; a high melting index of the material (HLMI) with a range of 15 about 0.5 g / 10 minutes to about 30 g / 10 minutes; and a critical tangential velocity for an onset of fracture by the fusion of the sliding rod greater than or equal to about 1000 sec. " DESCRIPTION OF THE PREFERRED MODALITIES The terms "polymer" and "copolymer" are used interchangeably in this disclosure. Both terms include a polymer product resulting from the polymerization of the ethylene monomer and a mono-1-olefin, or a large alpha-olefin, a comonomer, selected from the group consisting of propylene, 1-butene, 1-pentene, 1 -hexene, 1-octene, and / or 4-methyl-1-pentene.

Catalyst Systems As used in this disclosure, the term "support" refers to a support for another catalyst component. In any case, by no means, necessarily a support is an inert material; it is possible that a support can contribute to the catalytic activity and selectivity. The catalyst system support used in this invention can be a silica-titania support. As used in this disclosure, when referring to "silica" means a silica-containing material generally composed of 80 to 100 weight percent silica, the remainder, if any, are selected from one or more inorganic oxides, as reveals in the art, useful as supports of the catalyst system. For example, a silica-containing material may consist essentially of silica and not more than 0.2 weight percent of alumina or other metal oxides. Other ingredients that do not adversely affect the catalyst system or that are present to produce some unconnected results may also be present. The support may contain less than about 5 weight percent titanium (Ti), based on the weight of the support.

Preferably, the support comprises from 2 to about 5, and more preferably from 2 to 4, percent by weight of titanium, in order to produce a polymer with more desirable physical properties. The silica-titania supports are well known in the technique and may be produced as disclosed in Dietz, US Patent No. 3,887,494, the disclosure of which is hereby incorporated by reference. The catalyst component can be a compound chrome. The chromium compound, or component, may be combined with the silica-titania support in any manner known in the art, such as by forming a terylene coprecipitate of the silica, titanium and chromium components. Alternatively, an aqueous solution of a water-soluble chromium component can be added to a hydrogel of the silica-titania component. Suitable water-soluble chromium compounds include, but are not limited to, chromium nitrate, chromium acetate and chromium trioxide. Alternatively a solution of a hydrocarbon-soluble chromium component, such as tertiary butyl chromate, a chromium diarena compound, biscyclopentadienyl chromium (II) or chromium acetylacetonate, can be used to impregnate the silica xanthan titania resulting after removing the water from the cogel The chromium component is used in an amount sufficient to give about 0.05 to about 5, preferably 0.5 to 2 weight percent chromium, based on the total weight of the chromium weight and the support after activation. The resulting chromium component on a silica-titania support is then subjected to activation in an oxygen-containing environment in any conventional manner used in the art. Because of the economy, the oxygen-containing environment * preferred is air, preferably dry air. Activation can be performed at an elevated temperature for about one-half to about 50 hours, preferably about 2 to about 10 hours, at a temperature within a range of about 900 ° F to about 1050 ° F. (about 455 ° C to about 565 ° C), preferably from about 965 ° F to about 1020 ° F. (about 520 ° C to about 550 ° C). Under these calcining conditions at least a substantial part of any chromium in a lower valence state is converted to the hexavalent form. After calcination or activation, the supported, oxidized catalyst system is cooled to near the room temperature, for example about 25 ° C, under an inert atmosphere, such as argon or nitrogen. The catalyst system must move away from contact with reducing compounds, water or other harmful, or use up compounds that deactivate. The system The catalyst used in the inventive process should not be subjected to a reduction treatment. A reduction treatment can cause a narrowing of the molecular weight distribution (DPM). This DPM narrowing can increase the critical tangential velocity for hardening instabilities due to fracture in the melt during processing of the polymer and can result in a roughened surface of the extruded article manufacture. A co-catalyst can be used in conjunction with the catalyst system; The cocatalyst may be a trialkyl boron compound, wherein the alkyl group has from about 1 to 12 carbon atoms, preferably from about 2 to about 5 carbon atoms per alkyl group. Exemplary trialkyl boron compounds include, but are not limited to, tri-n-butyl borane, tripropyl borane and triethyl borane (TEB). These cocatalysts can be effective agents for improving the properties of the resulting polymer, such as, for example, reducing melt flow or delaying dilation during polymerization. By far the most preferred cocatalyst is triethylboron (TEB), due to the easy use in the polymerization reactor and improves the development of polymer properties. The trialkyl boron cocatalyst can be used in an amount within the range of about 1 to 20 parts per million (ppm), or milligrams per kilogram (mg / Kg), based on the mass of the ethylene monomer in the reactor. Preferably, the cocatalyst is used in an amount within the range of 2 to 10 ppm, and more preferably, within the range of about 3 to 6 ppm, for cost effectiveness and to improve polymer properties. Optionally, the trialkyl boron cocatalyst can be used in conjunction with a small amount of the trialkyl aluminum cocatalyst. Which is expected not to be limited in theory, it is believed that a small amount of a trialkyl aluminum cocatalyst can be used as a preservative for the trialkyl boron cocatalyst, to protect the trialkyl boron cocatalyst from inadvertent contact with air, or oxygen. Exemplary trialkyl aluminum cocatalysts include, but are not limited to, triethylaluminum, ethylaluminum sesquichloride, chloride * Diethylaluminum, and mixtures of these. Preferably the trialkylaluminum cocatalyst is triethylaluminum to improve the catalyst system and compatibility with the trialkyl boron cocatalyst. The trialkyl aluminum cocatalyst, if used, can be used in an amount within a range of about 0.1 to about 5 parts per million (ppm), or milligrams per kilogram (mg / Kg), based on the mass of the diluent in the reactor. Preferably, the trialkyl aluminum cocatalyst is used in an amount within the range of about 0.5 to about 3 ppm, and more preferably, within the range of about 0.5 to about 2 ppm, for cost effectiveness and to improve the properties of the polymer. » Reagents The polymers produced according to the process of this invention can be copolymers. This inventive process is of particular applicability in the production of large ethylene and alpha-olefin copolymers. The ethylene monomer may be polymerized with a comonomer selected from the group consisting of propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, and mixtures thereof. The ethylene is the most preferred monomer, due to the advantageous properties of the resulting copolymer. Preferably, the comonomer is 1-hexene and / or 4-methyl-1-pentene to achieve the maximum hardness of the polymer. The comonomer is added to the polymerization reactor, or reaction zone, in an amount within a range of about 0.5 to about 15 weight percent, preferably within a range of about 1 to about 10 weight percent, based on in the weight of the monomer. More preferably, the comonomer is present in the reaction zone within a range of about 2 to about 6 percent in order to produce a polymer with the most desired properties, such as, for example, reducing instabilities due to fracture in the fusion. Another method for expressing the amount of comonomer present in the gas separation reactor. Generally, the amount of comonomer present in the gas separation reactor has an amount in the range of about 0.05 to about 6 mole percent, based on the diluent in the reactor, such as isobutane. Preferably in the separation gas in an amount in the range of about 0.1 to about 2 mole percent, and more preferably, within the range of about 0.3 to about 1 mole percent, for cost effectiveness and improving the polymer properties.

Polymerization The polymerization of the ethylene and the comonomer can be carried out under stirring, or a particular form, the polymerization reaction conditions wherein the temperature of the reactor is keeps below the temperature at which the polymer is in solution. Such polymerization techniques are well known in the art and are disclosed, for example, in Norwood, U.S. Patent No. 3,248,179, the disclosure of which is incorporated herein by reference. the reference. The temperature of the polymerization reactor, or reaction zone, according to this invention, is critical and must be maintained within the range of about 180 ° F. to about 215 ° F. (about 82 to about 120 ° C), preferably within the range of about 180 ° F. at approximately 195 ° F (approximately 82 to 5 90 ° C). More preferably the temperature of the reaction zone is within a range of 180 ° F to 185 ° F. (82 ° C to 85 ° C.). Although high temperatures can be used in the reactor, operate within the ranges of. specified temperatures can produce a The copolymer can be subjected to further expansion during polymerization or instabilities due to melt fracture. The stirring process is generally carried out in an inert diluent (medium), such as, for example, a paraffin, cycloparaffin and / or aromatic hydrocarbon. Exemplary diluents include, but are not limited to, propane, n-butane, isobutane, n-pentane, 2-methylbutane (isopentane), and mixtures thereof. Isobutane is the most preferred diluent due to the low cost and easy to use The pressures in the agitated polymerization process can vary from about 110 to about 700 psia (0.76-4.8 MPa) or greater. The catalyst system is kept in suspension and can be contacted with the monomer and comonomer (s) at sufficient pressure to maintain the medium and at least a portion of the monomer and comonomer (s) in liquid phase. The medium and temperature are thus selected such that the copolymer is produced as solid particles and the copolymer is recovered in this form. The concentrations of the catalyst system in the reactor can be such that the The catalyst system contains ranges from 0.001 to about 1 weight percent based on the weight of the total contents of the reactor. Two preferred polymerization methods for the stirring process that employ recirculation in the reactor of the type disclosed in Norwood and these use a plurality of stirred reactors either in series, in parallel or combinations thereof where the reaction conditions are different in the different reactors. For example, in a series of reactors a chromium catalyst system can be used either before or after a reactor using a different catalyst system. In another example, a chromium catalyst system can be used in parallel with another reactor employing a "Different catalyst system in the polymerization and the resulting polymerization products can be combined before recovering a copolymer. In accordance with this invention, hydrogen can not be present in the polymerization reactor during polymerization. The presence of hydrogen gives * As a result a decrease and reduce the speed tangential criticism for the hardening of the fracture in the fusion for the resulting product. Which is expected not to be limited in theory, it is believed that the absence of hydrogen can leave a high molecular weight residue in the polymer which results in a Wide molecular weight distribution. Polymers having a broad molecular weight distribution may have fewer melt fractures, for example, a high critical tangential velocity. The catalyst system, cocatalyst, monomer, and The comonomer can be added to the reaction zone in any order, according to any method known in the art. For example, the catalyst system, cocatalyst, monomer and comonomer can be added simultaneously to the reaction zone. If desired, the catalyst and cocatalyst system can be precontacted under an inert environment prior to contacting the monomer and / or comonomer. Optionally, contacting the catalyst system and the cocatalyst before the catalyst system contacts the ethylene can reduce the amount of cocatalyst needed in the reaction zone. This precontact can reduce the amount of trialkyl boron cocatalyst necessary in the reaction zone above a factor above ten (10).

Product The polymers produced in accordance with this invention are a copolymer of ethylene and at least one large mono-1-olefin comonomer. The copolymers produced according to this invention have a broad molecular weight distribution and therefore have high critical tangential speeds and reduced instabilities due to melt fracture. Additionally, the speed of production of these and reduced instabilities due to fracture in the fusion. Additionally, the production speed of these copolymers in articles of manufacture can be increased significantly; consequently, the polymers produced according to this invention exhibit high production rates during the blow molding process. The density of this novel copolymer is usually within the range of about 0.935 g / cc to about 0.96, preferably from about 0.94 to about 0.958 g / cc. More preferably, the density of the copolymer is within a range of about 0.945 to about 0.955 g / cc. Another definite physical characteristic of this copolymer is the high melting rate of the material (HLMI). Usually, the HLMI is within a range of about 0.5 to about 30 g / 10 minutes, preferably within a range of about 3 to about 10 g / 10 minutes. More preferably, the HLMI is within a range of about 4 to about 8 g / 10 minutes. tangential criticism for the hardening of the fracture by the fusion of this novel polymer is * greater than or equal to about 1000 sec "1, more preferably greater than or equal to about 1500 sec." More preferably, the critical tangential velocity of the polymers produced according to this invention is within the range of about 1800 sec "to about 6000 sec" 1. * A greater understanding of the present invention and its advantages are provided with reference to the following examples.

EXAMPLES The ethylene-hexene copolymers were prepared in a process to form the particle continuously by contacting the catalyst with the monomers, using a liquid that fills the reactor with recirculation, which has a volume of 23 gallons (87 liters), isobutane as the diluent, and occasionally some Hydrogen, as shown in the Examples. The reactor was operated to have a residence time of 1.25 hrs. The temperature of the reactor was varied over the range of 180 ° C. at 215 ° C, unless the state is different, and the pressure was 4 MPa (580 psi). TO * steady-state conditions, the isobutane feed rate was 46 1 / hr., the speed of the feed was about 30 lbs / hr, and the feed rate of 1-hexane was varied with control of the density of the polymer produced. The polymer was removed from the reactor at a rate of 25 lbs / hr. The catalyst systems 10 used were commercially available catalyst systems purchased from the W.R. Grace and Company, the Davison Business unit, designated as 963 Magnapore®. The polymer produced was collected from each of the operations and tested according to the following 15 procedures: The density (g / ml): ASTM D 1505-68 and ASTM D 1928, Condition C. Determined in a compression of the molded sample , cooled to about 15 ° C. per minute, and conditioned at room temperature for about 40 hours .

The high melt index of the material (HLMI) (g / 10 min.): ASTM D 1238, Condition E. Determined at 190 ° C with a weight of 21,600 grams. The Heterogeneity Index (Hl): Mw / Mn The critical tangential velocity (start of the channels) (sec "): The determination of the critical tangential velocity developed by Dr. Ashish Sukhadia by Phillips Petroleum Company as a result of a need To determine precisely the start of the channels, the test apparatus is an Established Hair Extruder consisting of one (1) inch Killion® (KL-100) single extruder screw that is used to provide a fusion of the pressurized polymer for a given through an adapter to connect: Each die consists of two separate pieces: 1) an input die (zero fixed length) and 2) a fixed die (a die that has the same diameter as the input die but without a , constant diameter, a fixed region.) A complete determination of the results in a flow curve for the tested material The procedure consists in extruding the material (polymer) first with only the input die. on registered the flow rate, the pressure drop in the extruder, the pressure drop in * the adapter (mounted just before the dice) and the melting temperature. Then, a fixed die of a desired fixed length is placed at the end of the input die and the experimental procedure is repeated. In addition the data, the visual appearance of the extruded (strand) are recorded for both the input die and the input die plus the fixed die experienced. The 10 data are used to calculate the apparent tangential velocity and the shear stress. Standard calculation methods are used; see C.D. Han, Rheolo and on Polymer Processing, pp. 89-126, Academic Press, NY (1976). In addition a graphic plane of the flow curve (the true cutting tension vs. the apparent cutting voltage) is graphical. The following calculations are used: (32) (Q) Cover = Equation (1) (p) (D) *? P cover = Equation (2) 4 (L / D) ? P-? Pent 10 tverd = Equation (3) 4 (L / D) fifteen . Where L = Fixed length of capillary, inches D = Diameter of capillary die, inches = Diameter of fixed die, inches Q = Speed of volumetric flow, 20 inches / sec.

Apparent tangential speed, 1 / sec. taPar = apparent shear stress, MPa tverd = True shear stress (corrected), MPa ? Pent = Pressure drop at the entrance, MPa = Pressure drop through the die hole ? P = Total Pressure Drop, MPa = Pressure Drop Through Hole + Fixed Die The following conditions and dice were used: The diameter of the input die: 0.080 inches, 90 ° cone entrance angle Fixed die: diameter of 0.080 inches, 2.25 inches of fixed length (L / D ratio = 15) Temperature: 215 ° C. The profile of the fixed temperature of the extruder and the capillary Example 1 The polymer samples were prepared as described above. Different activations of the catalyst systems and different levels of triethylboron (TEB) were used. Triethylaluminum (TEA) was not added to the reactor; the hydrogen was added to the polymerization reactor in embodiment 102 and was present in an amount of 0.2 moles of hydrogen per mole of ethene. The embodiments 105 and 106 are commercially available polymers, used for comparison.

TABLE 1 (b) Polyethylene commercially available by Novacor N / A Not available The data in Table 1 shows that TEB can be used in conjunction with a chromium catalyst system to reduce fracture in the melt. Comparison of embodiments 101 with 102 and 103 with 104 show that large desirable levels of TEB delay the onset of fracture in the melt, or channels, by allowing high extruder screw speeds (fast). The data 10 in Table 1 further demonstrates that a low catalyst activation temperature can also increase the start of the channels.

Example 2 Samples of the polymers were prepared as described above. Different activation temperatures of the catalyst systems and different levels of triethylboron (TEB) were used. Triethylaluminum (TEA) was not added to the reactor.

TABLE 2 ^^ The data in Table 2, again, demonstrate that the low activation temperatures of the catalyst systems may differ from the start of the channels, up to high extruder speeds. The data in Table 2 also allows to show that the absence of hydrogen in the polymerization reactor • it allows large transfers in the extruder, or screw speeds, before the start of the channels. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention.

* Having described the invention as above, it is claimed as property contained in the following.

BB1

Claims (15)

1. A process for polymerizing mono-1-olefins, characterized in that it comprises contacting in a reaction zone, at a temperature within a range close to 180 ° F. at about 215 ° F., in the absence of hydrogen: a) ethylene monomer; b) at least one mono-1-olefin comonomer having from about 2 to about 8 carbon atoms per molecule; c) a catalyst system comprises chromium supported on a silica-titania support, wherein said support comprises from about 2 to about 10 weight percent titanium, based on the weight of the support, and wherein said catalyst system has been activated at a temperature within the range of about 900 ° F. at about 1050 ° F .; and d) a trialkyl boron compound; and recovering an ethylene / mono-1-olefin copolymer.

2. A process according to claim 1, • characterized in that said temperature of the reaction zone is within the range near 180 ° F. about 5 of 195 ° F.

3. A process according to claim 1 or 2, characterized in that said mono-1-olefin comonomer is propylene, 1-butene, 1-pentene, 1-hexene, 1-10 octene, 4-methyl-1-pentene, or mixtures of any of two or more of these comonomers.

4. A process according to claim 3, characterized in that said comonomer is 1-hexene.

5. A process according to any of the preceding claims, characterized in that said catalyst system is activated at a temperature within the range of about 965 ° F. to about 1020 ° F.

6. A process according to any of the preceding claims, characterized in that said trialkyl boron compound is tri-n-butyl borane, tripropyl borane, triethylborane, or a mixture of any two or more of said trialkyl boron compounds.

7. A process according to claim 6, characterized in that said trialkyl boron compound is triethylborane.

8. A process according to any of the preceding claims, characterized in that said resultant ethylene copolymer comprises: a) a density within a range of about 0.935 g / cc to about 0.96 g / cc; 15 b) a high melting rate of the material within a range of about 0.5 g / 10 minutes to about 30 g / 10 minutes, and c) a critical tangential velocity for the start of the fracture by melting greater than or equal to near 20 of 1200 sec "1.

9. A composition comprising a high molecular weight ethylene / mono-1-olefin copolymer, * characterized because it has: a) a density within a range of about 0.935 5 g / cc to about 0.96 g / cc; b) a high melting rate of the material within a range of about 0.5 g / 10 minutes to about 30g / 10 minutes, and c) a critical tangential velocity for the start 10 of the melting fracture of greater than or equal to about of 1200 sec "1.

10. A composition according to claim 9, characterized in that the copolymer has a 15 density within a range near 0.940 g / cc to about 0.955 g / cc.

11. A composition according to claim 9 or 10, characterized in that the copolymer has a 20 high melting index of the material within a range about 1 g / 10 minutes to about 20 g / 10 minutes.

12. A composition according to any of claims 9-11, characterized in that the copolymer has a critical tangential velocity for the beginning of the fracture by melting from greater to near 5 of 1900 sec "1.

13. A process for the polymerization of mono-1-olefins, characterized in that it is substantially described herein with reference to any of the 10 examples.

14. A composition comprises a high molecular weight ethylene / mono-1-olefin copolymer, characterized in that substantially as it is here 15 described with reference to any of the examples.

15. A copolymer produced by a process, characterized in that it is in accordance with any of claims 1-13. twenty