Biaxially Oriented Ethylene Copolymer

Abstract

Ethylene copolymers comprising ethylene and at least one alpha olefin having 4 to 8 carbon atoms have a viscosity of 0.940 to 0.960 g / cm 3 The ethylene copolymers have a density of 1000 .mu.m, a molecular weight distribution Mw / Mn of 9-12, and an Mz of greater than 500,000. The ethylene copolymers are made in a multi-zone reactor system under solution phase polymerization conditions and are useful for the preparation of biaxially oriented polyethylene (BOPE) films.

Description

[Technical Field]

[0001] ethylene and at least one alpha olefin having 4 to 8 carbon atoms, and 3 Ethylene copolymers having a density of 1000 .ANG. are made in a multi-zone reactor system under solution phase polymerization conditions and are useful for forming biaxially oriented films. [Background technology]

[0002] Biaxially oriented polyethylene (BOPE) films are typically prepared by stretching a thick precursor (or base) film, known as a cast sheet, in two directions: the machine direction (MD) and the transverse direction (TD). Stretching can be done in a single step (simultaneous biaxial stretching) or in two successive steps (sequential biaxial stretching). The apparatus used in the stretching process is commonly called a "tenter frame" line.

[0003] Compared to conventional blown films, BOPE films can achieve up to twice the stiffness (tensile modulus), improved tensile strength, impact strength, puncture resistance, flex crack resistance, and improved (i.e., lower) optical haze.

[0004] BOPE film is suitable for a wide variety of packaging applications. Its excellent properties allow for the design of "all-polyethylene packages" (as opposed to packages made with a different type of polymer), which makes them easier to recycle.

[0005] The tenter frame process is widely used to prepare biaxially oriented polypropylene (BOPP) and biaxially oriented polyethylene terephthalate (BOPET) films. However, polyethylene is relatively difficult to stretch / biaxially orient, which has limited the commercial use of BOPE. Therefore, there is a need for polyethylene that offers better "stretchability" in the BOPE process, tenter frame. Summary of the Invention

[0006] One embodiment of the present disclosure is an ethylene copolymer comprising ethylene and at least one alpha olefin having from 4 to 8 carbon atoms, the ethylene copolymer having a viscosity of from 0.940 to 0.960 grams per cubic centimeter (g / cm 3 a melt index I2 of 0.5 to 2.5 grams per 10 minutes (g / 10 min), measured according to ASTM D1238 at 190°C using a 2.16 kilogram load; a stress index of 1.75 to 1.95; a number average molecular weight Mn of 11,000 to 15,000; a polydispersity index (Mw / Mn) of 9 to 12; and a Z-average molecular weight Mz of 500,000 to 800,000.

[0007] One embodiment of the present disclosure is a solution phase polymerization process for making ethylene copolymers in a multi-zone reactor system, the multi-zone reactor system including first, second, and third polymerization zones, the first polymerization zone being defined by a first tubular reactor having an inlet and an outlet, the polymerization process comprising: supplying a solvent, hydrogen, a Ziegler-Natta polymerization catalyst, ethylene, and at least one alpha olefin having from 4 to 8 carbon atoms to an inlet of the first tubular reactor to initiate a polymerization reaction; supplying hydrogen to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor; wherein at least 80 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor; and wherein 20 to 50 weight percent of the total amount of ethylene copolymer made in the multi-zone reactor system is made in the first tubular reactor.

[0008] One embodiment of the present disclosure is a solution phase polymerization process for making an ethylene copolymer in a multi-zone reactor system, the multi-zone reactor system including first, second, and third polymerization zones, the first polymerization zone being defined by a first tubular reactor having an inlet and an outlet, the polymerization process comprising the steps of: supplying a solvent, hydrogen, a Ziegler-Natta polymerization catalyst, ethylene, and at least one alpha olefin having from 4 to 8 carbon atoms to an inlet of the first tubular reactor to initiate a polymerization reaction; supplying hydrogen to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor; wherein at least 80 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor; and producing the ethylene copolymer at a densitometric concentration of from 0.940 to 0.960 grams per cubic centimeter (g / cm 3a melt index I2 of 0.5 to 2.5 grams per 10 minutes (g / 10 min), measured according to ASTM D1238 at 190°C using a 2.16 kilogram load; a stress index of 1.75 to 1.95; a number average molecular weight Mn of 11,000 to 15,000; a polydispersity index (Mw / Mn) of 9 to 12; and a Z-average molecular weight Mz of 500,000 to 800,000.

[0009] One embodiment of the present disclosure is a biaxially oriented polyethylene film comprising an ethylene copolymer, the ethylene copolymer comprising ethylene and at least one alpha olefin having from 4 to 8 carbon atoms; the ethylene copolymer having a viscosity of 0.940 to 0.960 grams per cubic centimeter (g / cm 3 a melt index I2 of 0.5 to 2.5 grams per 10 minutes (g / 10 min), measured according to ASTM D1238 at 190°C using a 2.16 kilogram load; a stress index of 1.75 to 1.95; a number average molecular weight Mn of 11,000 to 15,000; a polydispersity index (Mw / Mn) of 9 to 12; and a Z-average molecular weight Mz of 500,000 to 800,000. [Brief explanation of the drawings]

[0010] [Figure 1] 1 shows a schematic diagram of one embodiment of the present disclosure, in which a multi-zone reactor system includes a first polymerization zone defined by a first tubular reactor, a second polymerization zone defined by a tank reactor, and a third polymerization zone defined by a second tubular reactor. The schematic diagram is merely representative of the multi-zone reactor system and is not drawn to scale. The approximate locations of hydrogen addition to the multi-zone reactor system are also shown (locations A and B). [Figure 2] 1 shows gel permeation chromatographs (GPC) with refractive index detection of ethylene copolymers made in accordance with the present disclosure and comparative polyethylenes. [Figure 3]Figure 3 shows gel permeation chromatographs with Fourier transform infrared (GPC-FTIR) detection obtained for ethylene copolymers made in accordance with the present disclosure and a comparative polyethylene. Comonomer content, shown as the number of short chain branches per 1000 main chain carbons (y-axis), is given versus the molecular weight of the copolymer (x-axis). The downward sloping line (left to right) is the short chain branching (short chain branches per 1000 carbon atoms) as determined by FTIR. As can be seen from Figure 3, for Inventive Examples 1 and 2, the comonomer incorporation is said to be "normal," since the number of short chain branches generally decreases with increasing molecular weight. [Figure 4] 1 shows the CTREF elution temperature profiles obtained for ethylene copolymers made in accordance with the present disclosure and comparative polyethylenes. [Figure 5] 1 shows differential scanning calorimetry (DSC) analyses and profiles of ethylene copolymers made in accordance with the present disclosure and comparative polyethylenes. [Figure 6] 1 shows the apparent shear viscosity (Pa·s) versus apparent shear rate (s −1 ) obtained by capillary rheology for ethylene copolymers made according to the present disclosure. [Figure 7] 1 shows DMA frequency sweep data (complex viscosity η* in Pa·s versus frequency ω in radians / s) for ethylene copolymers made according to the present disclosure and comparative polyethylenes. DETAILED DESCRIPTION OF THE INVENTION

[0011] As used herein, the term "monomer" refers to a small molecule that can chemically react and combine with itself or other monomers to form a polymer.

[0012] As used herein, the term "α-olefin" or "alpha-olefin" is used to describe a monomer having a linear hydrocarbon chain containing 3 to 20 carbon atoms and having a double bond at one end of the chain; an equivalent term is "linear α-olefin." Alpha olefins are sometimes also referred to as "comonomers."

[0013] As used herein, the terms "polyethylene" or "ethylene polymer" refer to a polymer produced from ethylene monomer and, optionally, one or more additional monomers, regardless of the specific catalyst or process used to make the ethylene polymer. In the polyethylene field, the one or more additional monomers are often referred to as "comonomers" and often include α-olefins. The term "homopolymer" refers to a polymer containing only one type of monomer. For example, an "ethylene homopolymer" is made using only ethylene as the polymerizable monomer. The term "copolymer" refers to a polymer containing two or more types of monomers. An "ethylene copolymer" is made using ethylene and one or more other polymerizable monomers (e.g., alpha-olefins). Common polyethylenes include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), very low-density polyethylene (VLDPE), or very low-density polyethylene (ULDPE), also known as plastomers and elastomers. The term polyethylene also includes polyethylene terpolymers, which may contain two or more comonomers in addition to ethylene. The term polyethylene also includes combinations or blends of the above polyethylenes.

[0014] In the present disclosure, a solution phase polymerization process is carried out in a multi-zone reactor system to prepare ethylene copolymers comprising ethylene and at least one alpha olefin having from 4 to 8 carbon atoms.

[0015] In the present disclosure, a solvent, polymerizable monomers (eg, ethylene and at least one alpha olefin), polymerization catalyst components, and hydrogen are fed into a multi-zone reactor system.

[0016] In one embodiment of the present disclosure, the multi-zone reactor system is further defined by first, second and third polymerization zones.

[0017] In one embodiment of the present disclosure, the first polymerization zone is defined by a first tubular reactor having an upstream inlet located at the upstream end of the first tubular reactor and a downstream outlet located at the downstream end of the first tubular reactor. In one embodiment of the present disclosure, the first polymerization zone is defined by a first tubular reactor having an upstream inlet located at the upstream end of the first tubular reactor, a downstream outlet located at the downstream end of the first tubular reactor, and one or more additional process flow entry points located along the length of the first tubular reactor at one or more locations between the upstream inlet and the downstream outlet.

[0018] In one embodiment of the present disclosure, the second polymerization zone is defined by a tank (or autoclave) reactor. In one embodiment of the present disclosure, the second polymerization zone is defined by a tank (or autoclave) reactor having an inlet and an outlet. In one embodiment of the present disclosure, the second polymerization zone is defined by a tank (or autoclave) reactor having an inlet and an outlet, and one or more additional process flow entry points located between the inlet and the outlet.

[0019] In an embodiment of the present disclosure, the tank reactor is a stirred tank reactor that optionally includes an agitator.

[0020] In one embodiment of the present disclosure, the third polymerization zone is defined by a second tubular reactor having an upstream inlet located at the upstream end of the second tubular reactor and a downstream outlet located at the downstream end of the second tubular reactor. In one embodiment of the present disclosure, the third polymerization zone is defined by a second tubular reactor having an upstream inlet located at the upstream end of the second tubular reactor, a downstream outlet located at the downstream end of the second tubular reactor, and one or more additional process flow entry points located along the length of the second tubular reactor at one or more locations between the upstream inlet and the downstream outlet.

[0021] Referring to FIG. 1 , in one embodiment of the present disclosure, ethylene copolymers were prepared in a multi-zone solution polymerization process in which three polymerization zones, each defined by a different polymerization reactor, were arranged in series with one another. The first polymerization zone was defined by a first tubular reactor (Reactor 1), the second polymerization zone was defined by an optionally stirred tank reactor (Reactor 2), and the third polymerization zone was defined by a second tubular reactor (Reactor 3). Each reactor had an inlet through which the process flow entered the reactor and an outlet through which the process flow exited the reactor. In the case of the tubular reactor (Reactor 1 or Reactor 3), the inlet was located at the upstream end of the tubular reactor, and the outlet was located at the downstream end of the tubular reactor. The inlet of the first tubular reactor received polymerization process feeds (pumped into the upstream inlet of the first tubular reactor), such as polymerization process solvent, polymerization catalyst components, cocatalyst, polymerizable monomers (e.g., ethylene and alpha-olefins), and hydrogen. The polymerization reaction is initiated at the upstream inlet of the first tubular reactor and proceeds throughout the length of the first tubular reactor as the process flow is pumped downstream toward the outlet of the first tubular reactor. An optionally stirred tank reactor (Reactor 2) receives the process flow from the first tubular reactor, and the polymerization reaction continues within the tank reactor. A second tubular reactor (Reactor 3) receives the process flow from the tank reactor, and the polymerization reaction continues throughout the length of the second tubular reactor. At the outlet of the second tubular reactor, the polymerization reaction is stopped by adding a catalyst deactivator. Various deactivators are known; non-limiting examples include fatty acids, alkaline earth metal salts of aliphatic carboxylic acids, and alcohols. The polymer can then be recovered in a conventional manner by process solvent devolatilization (not shown in Figure 1). Conventional distillation equipment may be used to recover the solvent and unreacted comonomer (not shown in Figure 1).

[0022] In one embodiment of the present disclosure, the ethylene copolymer is recovered from the solution using known unit operations including a heater, an optional absorber to remove catalyst residues, an intermediate pressure separator (IPS), and a pair of two-stage steam-fed low pressure separators (LPS). The recovered ethylene copolymer is then pelletized in an extruder and devolatilized in a stripper to remove residual solvent and comonomer.

[0023] In one embodiment of the present disclosure, the first tubular reactor (Reactor 1) is operated adiabatically.

[0024] In one embodiment of the present disclosure, the tank reactor (Reactor 2) is operated adiabatically.

[0025] In one embodiment of the present disclosure, the second tubular reactor (Reactor 3) is operated adiabatically.

[0026] In one embodiment of the present disclosure, the multi-zone reactor system is operated adiabatically.

[0027] In this disclosure, the phrase "adiabatically operated" refers to a reactor or multi-zone reactor system that has no active heat removal or addition mechanisms.

[0028] In one embodiment of the present disclosure, the tank reactor (Reactor 2) is a stirred tank reactor, optionally with an agitator present, but the tank reactor is operated without agitation and therefore functions not as a continuously stirred tank reactor but instead as a type of plug flow reactor. In this disclosure, a tank (or autoclave) reactor equipped with an agitator is said to be operating in "plug flow mode" when the agitator is turned off. Without wishing to be bound by theory, when the tank reactor (Reactor 2) is used without agitation, the multi-zone reactor system can be described as a long tubular reactor system containing three polymerization reaction zones, each defined by a tubular reactor having a different diameter (and optionally operating adiabatically).

[0029] In one embodiment of the present disclosure, the monomers polymerized in the solution phase polymerization process are ethylene and 1-butene.

[0030] Although a wide variety of solvents can be used in the solution phase polymerization process, in one embodiment of the present disclosure, the solvent is a hydrocarbon solvent.

[0031] In an embodiment of the present disclosure, the solvent used in the solution phase polymerization process is cyclohexane or methylcyclohexane.

[0032] In one embodiment of the present disclosure, all monomers (e.g., ethylene and one or more alpha olefins) used in the solution-phase polymerization are fed to the inlet of the first tubular reactor (Reactor 1). In one embodiment of the present disclosure, all monomers (e.g., ethylene and one or more alpha olefins) and catalyst components (e.g., Ziegler-Natta pre-catalyst components and cocatalyst) used in the solution-phase polymerization are fed to the inlet of the first tubular reactor (Reactor 1). In these embodiments, without wishing to be bound by theory, as the polymer solution flows through the multi-zone reactor system, additional polymer is formed under conditions where the ethylene (and alpha olefin comonomer) concentration decreases and the temperature increases. At this time, monomer conversion continues in the tank reactor (Reactor 2) and the second tubular reactor (Reactor 3), optionally without adding additional catalyst to these reactors. Those skilled in the art will recognize that, if each individual reactor is equipped with equipment to measure temperature, the ethylene conversion can be estimated / determined in each reactor using heat and mass balances using well-known techniques.

[0033] In embodiments of the present disclosure, the amount of ethylene copolymer formed in each reactor will be a function of several variables, such as, for example, active polymerization catalyst concentration (which may depend on the molar ratio of cocatalyst compound to precatalyst compound), monomer (e.g., ethylene and alpha-olefin) concentration, reactor temperature, and polymerization hold-up time.

[0034] In an embodiment of the present disclosure, the polymerization hold-up time in each of the first tubular reactor (Reactor 1), the tank reactor (Reactor 2), and the second tubular reactor (Reactor 3) is adjusted to control the amount of ethylene copolymer made in each reactor. The polymerization hold-up time is the time during which polymerizable monomers are polymerized in the presence of an active polymerization catalyst to produce ethylene copolymer. The polymerization hold-up time can be adjusted by changing variables such as the process flow or throughput rate, the reactor volume, and the feed location of the polymerization catalyst components into the reactors.

[0035] In an embodiment of the present disclosure, the polymerization hold-up time in the first tubular reactor (reactor 1) is 0.5 to 100 seconds, or 1 to 15 seconds.

[0036] In an embodiment of the present disclosure, the polymerization hold-up time in the tank reactor (reactor 2) is at least 0.5 minutes or 1.0 to 7.0 minutes.

[0037] In one embodiment of the present disclosure, 15 to 60 weight percent of the total amount of ethylene copolymer made in the multi-zone reactor system is made in the first tubular reactor (Reactor 1). In one embodiment of the present disclosure, 20 to 50 weight percent of the total amount of ethylene copolymer made in the multi-zone reactor system is made in the first tubular reactor (Reactor 1). In one embodiment of the present disclosure, 30 to 40 weight percent of the total amount of ethylene copolymer made in the multi-zone reactor system is made in the first tubular reactor (Reactor 1).

[0038] In one embodiment of the present disclosure, 60 weight percent or less of the total amount of ethylene copolymer made in the multi-zone reactor system is made in the tank reactor (Reactor 2). In one embodiment of the present disclosure, 50 weight percent or less of the total amount of ethylene copolymer made in the multi-zone reactor system is made in the tank reactor (Reactor 2).

[0039] In one embodiment of the present disclosure, about 10 weight percent of the total amount of ethylene copolymer made in the multi-zone reactor system is made in the second tubular reactor (reactor 3). In one embodiment of the present disclosure, less than 10 weight percent of the total amount of ethylene copolymer made in the multi-zone reactor system is made in the second tubular reactor (reactor 3).

[0040] In one embodiment of the present disclosure, hydrogen is used as a chain transfer agent in a solution phase polymerization process.

[0041] In one embodiment of the present disclosure, hydrogen is supplied to both the inlet of the first tubular reactor (Reactor 1) and to at least one location within the first tubular reactor (Reactor 1) downstream from the inlet of the first tubular reactor.

[0042] In one embodiment of the present disclosure, hydrogen is supplied to both the inlet of the first tubular reactor (Reactor 1) and to at least one location within the first tubular reactor (Reactor 1) downstream from the inlet of the first tubular reactor and upstream of the inlet to the tank reactor (Reactor 2).

[0043] In one embodiment of the present disclosure, hydrogen is supplied to both the inlet of the first tubular reactor (Reactor 1) and to at least one location within the first tubular reactor (Reactor 1) downstream from the inlet of the first tubular reactor and proximate the inlet to the tank reactor (Reactor 2).

[0044] In one embodiment of the present disclosure, hydrogen is supplied to both the inlet of the first tubular reactor (Reactor 1) and to at least one location within the first tubular reactor (Reactor 1) that is 25% to 75% downstream from the inlet along the length of the first tubular reactor (specifically, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is at least one location within the tubular reactor that is 2.5 m to 7.5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor).

[0045] In one embodiment of the present disclosure, hydrogen is supplied to both the inlet of the first tubular reactor (Reactor 1) and to at least one location within the first tubular reactor (Reactor 1) that is 35% to 65% downstream from the inlet along the length of the first tubular reactor (specifically, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is 3.5 m to 6.5 m downstream from the inlet of said tubular reactor and along the length of said tubular reactor).

[0046] In one embodiment of the present disclosure, hydrogen is supplied to both the inlet of the first tubular reactor (Reactor 1) and to at least one location within the first tubular reactor (Reactor 1) that is 45% to 55% downstream from the inlet along the length of the first tubular reactor (specifically, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is 4.5 m to 5.5 m downstream from the inlet of said tubular reactor and along the length of said tubular reactor).

[0047] In one embodiment of the present disclosure, hydrogen is supplied to both the inlet of the first tubular reactor (Reactor 1) and to at least one location within the first tubular reactor (Reactor 1) that is about 50% downstream from the inlet along the length of the first tubular reactor (specifically, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is about 5 m downstream from the inlet of said tubular reactor and along the length of said tubular reactor).

[0048] In one embodiment of the present disclosure, at least 60 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor.

[0049] In one embodiment of the present disclosure, at least 60 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor and upstream of the inlet to the tank reactor (Reactor 2).

[0050] In one embodiment of the present disclosure, at least 60 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor and proximate the inlet to the tank reactor (Reactor 2).

[0051] In one embodiment of the present disclosure, at least 70 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor.

[0052] In one embodiment of the present disclosure, at least 70 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor and upstream of the inlet to the tank reactor (Reactor 2).

[0053] In one embodiment of the present disclosure, at least 70 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor and proximate the inlet to the tank reactor (Reactor 2).

[0054] In one embodiment of the present disclosure, at least 80 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor.

[0055] In one embodiment of the present disclosure, at least 80 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor and upstream of the inlet to the tank reactor (Reactor 2).

[0056] In one embodiment of the present disclosure, at least 80 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor and proximate the inlet to the tank reactor (Reactor 2).

[0057] In embodiments of the present disclosure, 60 to 97 weight percent, or 65 to 95 weight percent, or 70 to 95 weight percent, or 70 to 90 weight percent, or 75 to 97 weight percent, or 75 to 95 weight percent, or 80 to 95 weight percent, or 80 to 90 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor.

[0058] In embodiments of the present disclosure, 60 to 97 weight percent, or 65 to 95 weight percent, or 70 to 95 weight percent, or 70 to 90 weight percent, or 75 to 97 weight percent, or 75 to 95 weight percent, or 80 to 95 weight percent, or 80 to 90 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor and upstream of the inlet to the tank reactor (Reactor 2).

[0059] In embodiments of the present disclosure, 60 to 97 weight percent, or 65 to 95 weight percent, or 70 to 95 weight percent, or 70 to 90 weight percent, or 75 to 97 weight percent, or 75 to 95 weight percent, or 80 to 95 weight percent, or 80 to 90 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor and proximate the inlet to the tank reactor (Reactor 2).

[0060] In one embodiment of the present disclosure, at least 60 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is 25% to 75% downstream from the inlet along the length of the first tubular reactor. (For clarity, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is 2.5 m to 7.5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor.)

[0061] In one embodiment of the present disclosure, at least 60 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is 35% to 65% downstream from the inlet along the length of the first tubular reactor. (For clarity, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is 3.5 m to 6.5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor.)

[0062] In one embodiment of the present disclosure, at least 60 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is 45% to 55% downstream from the inlet along the length of the first tubular reactor. (For clarity, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is 4.5 m to 5.5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor.)

[0063] In one embodiment of the present disclosure, at least 60 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is about 50% downstream from the inlet along the length of the first tubular reactor (specifically, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is about 5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor).

[0064] In one embodiment of the present disclosure, at least 70 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is 25% to 75% downstream from the inlet along the length of the first tubular reactor. (For clarity, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is 2.5 m to 7.5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor.)

[0065] In one embodiment of the present disclosure, at least 70 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is 35% to 65% downstream from the inlet along the length of the first tubular reactor. (For clarity, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is 3.5 m to 6.5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor.)

[0066] In one embodiment of the present disclosure, at least 70 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is 45% to 55% downstream from the inlet along the length of the first tubular reactor. (For clarity, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is 4.5 m to 5.5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor.)

[0067] In one embodiment of the present disclosure, at least 70 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is about 50% downstream from the inlet along the length of the first tubular reactor (specifically, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is about 5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor).

[0068] In one embodiment of the present disclosure, at least 80 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is 25% to 75% downstream from the inlet along the length of the first tubular reactor. (For clarity, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is 2.5 m to 7.5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor.)

[0069] In one embodiment of the present disclosure, at least 80 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is 35% to 65% downstream from the inlet along the length of the first tubular reactor. (For clarity, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is 3.5 m to 6.5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor.)

[0070] In one embodiment of the present disclosure, at least 80 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is 45% to 55% downstream from the inlet along the length of the first tubular reactor. (For clarity, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is 4.5 m to 5.5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor.)

[0071] In one embodiment of the present disclosure, at least 80 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is about 50% downstream from the inlet along the length of the first tubular reactor (specifically, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is about 5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor).

[0072] In embodiments of the present disclosure, 60 to 97, or 65 to 95, or 70 to 95, or 70 to 90, or 75 to 97, or 75 to 95, or 80 to 95, or 80 to 90 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is 25% to 75% downstream from the inlet along the length of the first tubular reactor. (For clarity, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is 2.5 m to 7.5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor.)

[0073] In embodiments of the present disclosure, 60 to 97, or 65 to 95, or 70 to 95, or 70 to 90, or 75 to 97, or 75 to 95, or 80 to 95, or 80 to 90 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is 35% to 65% downstream from the inlet along the length of the first tubular reactor. (For clarity, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is 3.5 m to 6.5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor.)

[0074] In embodiments of the present disclosure, 60 to 97, or 65 to 95, or 70 to 95, or 70 to 90, or 75 to 97, or 75 to 95, or 80 to 95, or 80 to 90 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is 45% to 55% downstream from the inlet along the length of the first tubular reactor. (For clarity, if the first tubular reactor has a length of 10 m, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is 4.5 m to 5.5 m downstream from the inlet of said tubular reactor along the length of said tubular reactor.)

[0075] In embodiments of the present disclosure, 60 to 97, or 65 to 95, or 70 to 95, or 70 to 90, or 75 to 97, or 75 to 95, or 80 to 95, or 80 to 90 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor that is about 50% downstream from the inlet along the length of the first tubular reactor (specifically, if the first tubular reactor has a length of 10 meters, the "at least one location within the first tubular reactor" to which hydrogen is supplied is a location within the tubular reactor that is about 5 meters downstream from the inlet of said tubular reactor along the length of said tubular reactor).

[0076] In embodiments of the present disclosure, the solution phase polymerization process can be carried out at a temperature of from 105°C to 320°C, or from 130°C to 250°C, or from 140°C to 230°C.

[0077] In embodiments of the present disclosure, the solution phase polymerization process can be carried out at a pressure of from about 4 to about 20 MPa, or from about 8 to about 20 MPa.

[0078] In an embodiment of the present disclosure, the temperature in the first tubular reactor (reactor 1) is in the range of 50 to 250°C, or 60 to 230°C, or 75 to 230°C.

[0079] In an embodiment of the present disclosure, the temperature rise over the length of the first tubular reactor (reactor 1) is from 20 to 150°C, or from 20 to 120°C.

[0080] In an embodiment of the present disclosure, the temperature inside the tank reactor (reactor 2) is 150 to 320°C, or 200 to 275°C.

[0081] In an embodiment of the present disclosure, the pressure in the first tubular reactor (reactor 1) is 8 to 20 MPa, or 10 to 20 MPa, or 12 to 16 MPa.

[0082] In an embodiment of the present disclosure, the pressure in the tank reactor (reactor 2) is 8 to 20 MPa, or 10 to 20 MPa, or 12 to 16 MPa.

[0083] In an embodiment of the present disclosure, the first tubular reactor (reactor 1) has a volume of 250 to 5,000 liters, or 350 to 2,500 liters, or 350 to 1,000 liters, or 400 to 1,000 liters.

[0084] In an embodiment of the present disclosure, the first tubular reactor (Reactor 1) has a length-to-diameter ratio of 50-1000, or 50-750, or 75-500, or 100-500, or 200-400.

[0085] In an embodiment of the present disclosure, the tank reactor (reactor 2) has a volume of 500 to 5,000 liters, or 1,000 to 5,000 liters, or 1,500 to 5,000 liters, or 2,000 to 5,000 liters, or 2,500 to 4,500 liters.

[0086] In an embodiment of the present disclosure, the second tubular reactor (reactor 3) has a volume of 250 to 5,000 liters, or 500 to 4,000 liters, or 1,000 to 3,500 liters, or 1,500 to 4,000 liters, or 1,500 to 3,500 liters.

[0087] In embodiments of the present disclosure, the second tubular reactor (Reactor 3) has a length-to-diameter ratio of 50 to 1,000, or 50 to 750, or 75 to 500, or 100 to 500, or 150 to 350.

[0088] In an embodiment of the present disclosure, the ratio of the volume of the first tubular reactor (Reactor 1) to the volume of the tank reactor (Reactor 2) is from 1:15 to 2:1, or from 1:10 to 1:1, or from 1:7.5 to 1:1, or from 1:5 to 1:1.

[0089] In embodiments of the present disclosure, the ratio of the volume of the first tubular reactor (Reactor 1) to the volume of the second tubular reactor (Reactor 3) is from 1:15 to 2:1, or from 1:10 to 1:1, or from 1:7.5 to 1:1, or from 1:5 to 1:1.

[0090] In an embodiment of the present disclosure, the volume of the second tubular reactor (Reactor 3) is about 60 to about 120% of the volume of the tank reactor (Reactor 2), or about 70 to about 100% of the volume of the tank reactor (Reactor 2), or about 75 to 95% of the volume of the tank reactor (Reactor 2), or about 75 to 85% of the volume of the tank reactor (Reactor 2), or about 80% of the volume of the tank reactor (Reactor 2).

[0091] In one embodiment of the present disclosure, pressure and temperature are maintained in a multi-zone reactor system at a temperature and pressure such that the ethylene copolymer formed remains in solution.

[0092] In embodiments of the present disclosure, the molecular weight (and therefore the melt index I2) and molecular weight distribution (M) of ethylene copolymers made in a multi-zone reactor system are w / M n ) can be adjusted by: i) changing the inlet temperature of the first tubular reactor (i.e., the temperature at which the polymerization process feed stream enters the upstream end of the first tubular reactor, e.g., polymerization solvent temperature and monomer temperature); ii) changing the amount of hydrogen fed to the process and / or changing the location at which hydrogen is fed into the multi-zone reactor system and / or changing the amount of hydrogen fed to each location fed into the multi-zone reactor system; and iii) changing the overall ethylene conversion or the ethylene conversion occurring in the first tubular reactor by varying the polymerization catalyst feed rate.

[0093] In further embodiments of the present disclosure, the molecular weight and molecular weight distribution of the ethylene copolymer can be adjusted by varying: the catalyst composition (such as the molar ratio of cocatalyst to precatalyst component); the average temperature of the first tubular reactor, the tank reactor, and / or the second tubular reactor; the temperature at the inlet or outlet of the first tubular reactor, the tank reactor, and / or the second tubular reactor; and the ethylene conversion in the tank reactor and / or the second tubular reactor.

[0094] In one embodiment of the present disclosure, the inlet temperature of the first tubular reactor (Reactor 1) (or the temperature of the feed mixture containing solvent, monomer, and catalyst components entering the inlet) is 30° C. to 150° C. In further embodiments of the present disclosure, the inlet temperature of the first tubular reactor (Reactor 1) is 75° C. to 150° C., or 90° C. to 150° C., or 75° C. to 130° C., or 90° C. to 125° C.

[0095] In an embodiment of the present disclosure, the inlet temperature of the first tubular reactor (Reactor 1) is less than 150°C, or less than 140°C, or less than 130°C, or less than 125°C.

[0096] In one embodiment of the present disclosure, at least 70 weight percent, or at least 75 weight percent, or at least 80 weight percent, or at least 85 weight percent, or at least 90 weight percent of the ethylene fed to the multi-zone reactor system is converted to ethylene copolymer (i.e., ethylene conversion is ≧70%, or ≧75%, or ≧80%, or ≧85%, or ≧90%).

[0097] <Polymerization catalyst> In one embodiment of the present disclosure, the ethylene copolymer is made in the presence of a Ziegler-Natta polymerization catalyst, examples of which are well known to those skilled in the art.

[0098] In one embodiment of the present disclosure, the ethylene copolymer is made in the presence of a Ziegler-Natta polymerization catalyst comprising vanadium, titanium, and aluminum.

[0099] In one embodiment of the present disclosure, the active Ziegler-Natta polymerization catalyst comprises three catalyst components. (i) a vanadium precatalyst compound, VOCl3; (ii) titanium precatalyst compounds titanium tetrahalides, TiX4, where X is a halide; (iii) a cocatalyst compound, trialkylaluminum, (R 1 ) 3Al compound or alkylaluminum alkoxide compound as a cocatalyst compound, R 2 AlOR 3 (In the formula, R 1 , R 2 and R 3 are C groups such as alkyl groups, 1-10 a hydrocarbyl group).

[0100] In one embodiment, the titanium precatalyst compound (ii) is titanium tetrachloride, TiCl4.

[0101] In one embodiment, the co-catalyst compound (iii) is triethylaluminum, (C2H5)3Al.

[0102] In one embodiment of the present disclosure, the pre-catalyst compound used to prepare an active Ziegler-Natta catalyst is a molar ratio of (i) VOCl3 and (ii) TiX4, where the molar ratio of V:Ti is from 5:95 to 70:30.

[0103] In one embodiment of the present disclosure, a cocatalyst compound (iii) (R 1 )3Al or R 2 AlOR 3 to the total metals provided by the pre-catalyst compounds (i) VOCl3 and (ii) TiX4, is an Al:(V+Ti) molar ratio of 0.1:1 to 100:1, or 0.5:1 to 50:1, or 0.5:1 to 25:1, or 0.5:1 to 10:1, or 0.5:1 to 5:1, or 0.75:1 to 10:1, or 0.75:1 to 5:1.

[0104] In one embodiment, the active Ziegler-Natta polymerization catalyst is prepared online by first mixing components (i) and (ii) and then adding component (iii).

[0105] In embodiments, the active Ziegler-Natta polymerization catalyst is prepared in-line by combining catalyst components (i), (ii), and (iii) in the presence of a solvent and / or diluent at a temperature of from 20°C to 150°C, or from 20°C to 100°C, or from 75°C to 150°C, or from 80°C to 100°C.

[0106] In one embodiment, the activated Ziegler-Natta polymerization catalyst is prepared online by mixing catalyst components (i), (ii), and (iii) in the presence of a solvent and / or diluent for a period of time ranging from 0.5 to 30 minutes, or from 0.5 to 15 minutes, or from 0.5 to 10 minutes, or from 0.3 to 3 minutes, prior to providing the activated catalyst to a polymerization zone or reactor.

[0107] In an embodiment of the present disclosure, the VOCl3 compound and the TiCl4 compound were first mixed in the presence of a solvent and / or diluent in a weight ratio (wt % VOCl3:wt % TiCl4) of 50:50 to 90:10, or 60:40 to 85:15, or 60:40 to 80:20, and then mixed with triethylaluminum at the inlet of the first tubular reactor just prior to injection into the first tubular reactor.

[0108] In one embodiment of the present disclosure, the VOCl3 compound and the TiCl4 compound were first mixed in a weight ratio ranging from 80:20 in the presence of a solvent and / or diluent, and then mixed with triethylaluminum at the inlet of the first tubular reactor just before injection into the first tubular reactor.

[0109] In one embodiment, the solvent used in the preparation of the active Ziegler-Natta polymerization catalyst is unsubstituted or 1-4 Inactive C optionally substituted with alkyl groups 6-10Non-limiting examples of suitable solvents that can be used in embodiments of the present disclosure include hexane, heptane, octane, cyclohexane, methylcyclohexane, and hydrogenated naphtha.

[0110] In one embodiment of the present disclosure, the solvent used in the preparation of the active Ziegler-Natta polymerization catalyst is the same as that fed into the multi-zone reactor system for the solution phase polymerization process.

[0111] <Ethylene copolymer> In one embodiment of the present disclosure, the ethylene copolymers are made using multi-site catalyst systems, non-limiting examples of which include Ziegler-Natta polymerization catalysts and chromium catalysts, which are well known in the art.

[0112] In one embodiment of the present disclosure, the ethylene copolymer is made using Ziegler-Natta polymerization catalysts known in the art.

[0113] In embodiments of the present disclosure, the alpha-olefins that may be copolymerized with ethylene to make the ethylene copolymer may be selected from the group including 1-butene, 1-pentene, 1-hexene, 1-octene, and mixtures thereof.

[0114] In one embodiment of the present disclosure, the ethylene copolymer comprises ethylene and at least one alpha olefin having from 4 to 8 carbon atoms.

[0115] In one embodiment of the present disclosure, the ethylene copolymer is an ethylene / 1-butene copolymer.

[0116] In an embodiment of the present disclosure, the ethylene copolymer has a viscosity of 0.940 to 0.965 g / cm 3 , or 0.940 to 0.963 g / cm 3 , or 0.940 to 0.960 g / cm 3 , or 0.940 to 0.958 g / cm 3 , or 0.940 to 0.956 g / cm 3, or 0.940 to 0.952 g / cm 3 , or 0.940 to 0.950 g / cm 3 , or 0.942 to 0.960 g / cm 3 , or 0.942 to 0.958 g / cm 3 , or 0.942 to 0.956 g / cm 3 , or 0.942 to 0.952 g / cm 3 , or 0.942 to 0.950 g / cm 3 It has a density of

[0117] In embodiments of the present disclosure, the ethylene copolymer has a melt index I2 of at least 0.50 g / 10 min, or at least 0.75 g / 10 min, or at least 0.80 g / 10 min, or at least 1.0 g / 10 min.

[0118] In an embodiment of the present disclosure, the melt index I2 of the ethylene copolymer may be from about 0.01 g / 10 min to about 10.0 g / 10 min, or from about 0.1 g / 10 min to about 10.0 g / 10 min, or from about 0.1 g / 10 min to about 5.0 g / 10 min, or from about 0.1 g / 10 min to about 3.0 g / 10 min, or from about 0.5 g / 10 min to about 5.0 g / 10 min, or from about 0.5 g / 10 min to about 3.0 g / 10 min, or from about 0.5 g / 10 min to about 2.5 g / 10 min.

[0119] In an embodiment of the present disclosure, the melt flow ratio (MFR) I of the ethylene copolymer 21 / I2 is greater than 50, or greater than 60, or greater than 65, or greater than 70, or greater than 75.

[0120] In one embodiment of the present disclosure, the melt flow ratio (MFR) I of the ethylene copolymer 21 / I2 is less than 115.

[0121] In an embodiment of the present disclosure, the melt flow ratio (MFR) I of the ethylene copolymer 21 / I2 is 50 to 120, or 50 to 115, or more than 65 and less than 115, or more than 75 and less than 115.

[0122] In one embodiment of the present disclosure, the ethylene copolymer has a MW of from about 5,000 to about 75,000, or from about 5,000 to about 50,000, or from about 5,000 to about 30,000, or from about 5,000 to about 25,000, or from about 7,500 to about 50,000, or from about 7,500 to about 30,000, or from about 7,500 to about 25,000, or from about 5,000 to about 20,000, or from about 5,000 to about 50,000. It has a number average molecular weight Mn of 0 to about 15,000, or about 7,500 to about 20,000, or about 7,500 to about 15,000, or about 10,000 to about 15,000, or about 10,000 to about 12,500, or about 11,000 to about 15,000, or about 11,000 to about 12,500, or more than 11,000 but less than 12,500, or more than 11,000 but less than 15,000.

[0123] In one embodiment of the present disclosure, the ethylene copolymer has a weight average molecular weight Mw of about 75,000 to about 250,000, or about 80,000 to about 200,000, or about 90,000 to about 175,000, or about 100,000 to about 175,000, or about 90,000 to about 150,000, or about 100,000 to about 150,000, or about 100,000 to about 125,000, or about 90,000 to about 130,000, or about 90,000 to about 125,000, or about 85,000 to about 140,000, or about 85,000 to about 150,000, or greater than about 85,000 but less than about 140,000.

[0124] In one embodiment of the present disclosure, the ethylene copolymer has a Z average molecular weight Mz of at least 500,000, or greater than 500,000, or at least 550,000, or greater than 550,000, or at least 600,000, or greater than 600,000.

[0125] In one embodiment of the present disclosure, the ethylene copolymer has a Z-average molecular weight Mz of from about 500,000 to about 800,000, or from greater than 500,000 to about 800,000, or from greater than 500,000 to less than 800,000, or from about 500,000 to 750,000, or from about 525,000 to about 750,000, or from about 550,000 to about 750,000, or from about 575,000 to about 750,000, or from about 550,000 to about 725,000, or from about 575,000 to about 725,000, or from about 600,000 to about 700,000.

[0126] In an embodiment of the present disclosure, the ethylene copolymer has a molecular weight distribution M of 8.0 to 12.0, or from greater than 8.0 to 12.0, or from 8.5 to 12.0, or from 9.0 to 12.0, or from greater than 9.0 to less than 12.0, 9.0 to 11.5, 8.5 to 11.5, 9.0 to 11.0, 8.0 to 11.0, 9.0 to 10.5, or 9.5 to 10.5. w / M n It has.

[0127] In an embodiment of the present disclosure, the ethylene copolymer has a Z-average molecular weight distribution, Mz / Mw, of from 3.5 to 8.0, or from 4.0 to 8.0, or from 4.0 to 7.5, or from 4.0 to 7.0, or from 4.5 to 7.5, or from 4.5 to 7.0, or from 4.5 to 6.5, or from 5.0 to 7.0, or from 5.5 to 7.0, or from 5.0 to 6.5, or from 5.5 to 6.5, or from greater than 5.0 to less than 6.5, or from 5.0 to 6.25, or from 5.0 to 6.0.

[0128] In one embodiment of the present disclosure, the ethylene copolymer is Log 10 [I6 / I2] / Log 10 It has a stress index defined as [6.48 / 2.16], and the stress index is 1.60 to 2.00, or 1.65 to 2.00, or 1.70 to 2.00, or 1.75 to 1.95, or 1.75 to 1.90, or 1.80 to 1.95, or 1.80 to 1.90, or more than 1.80 but less than 1.90.

[0129] In one embodiment of the present disclosure, the ethylene copolymer has a high Mz of about 500,000 or greater and a broad molecular weight distribution (M) of about 9.0 to about 12.0. w / M n ) is characterized by having.

[0130] In an embodiment of the present disclosure, the ethylene copolymer has a composition distribution breadth index CDBI of 40 to 75 wt%, or 50 to 70 wt%, or 55 to 70 wt%, or 55 to 65 wt%. 50 It has.

[0131] In an embodiment of the present disclosure, the ethylene copolymer has a composition distribution breadth index CDBI of 35 to 65 wt%, or 35 to 60 wt%, or 35 to 55 wt%, or 40 to 60 wt%, or 40 to 55 wt%, or 40 to 50 wt%, or more than 40 wt% to less than 50 wt%. 25 It has.

[0132] In one embodiment of the present disclosure, the ethylene copolymer has a unimodal profile in gel permeation chromatography (GPC). The term "unimodal" is defined herein to mean the presence of only one significant peak or maximum evident in the GPC curve. A unimodal profile includes broad unimodal profiles. A unimodal profile may also include shoulders or buried peaks that cannot be easily separated or deconvoluted into clearly defined unique peaks.

[0133] In one embodiment of the present disclosure, the ethylene copolymer has a normal comonomer distribution profile as measured using GPC-FTIR. If the comonomer incorporation decreases with molecular weight as measured using GPC-FTIR, the distribution is described as "normal." The term "normal comonomer distribution" is used herein to mean that the comonomer content of various polymer fractions across the molecular weight range of the ethylene copolymer is not substantially uniform, with higher molecular weight fractions having proportionally lower comonomer contents. If the comonomer incorporation is approximately constant with molecular weight as measured using GPC-FTIR, the comonomer distribution is described as "flat" or "uniform." The terms "inverse comonomer distribution" and "partially inverse comonomer distribution" refer to the presence of one or more high molecular weight components with higher comonomer incorporation than one or more low molecular weight components in GPC-FTIR data obtained for the copolymer. The term "reverse (or reversed) comonomer distribution" is used herein to mean that the comonomer content of the various polymer fractions across the molecular weight range of an ethylene copolymer is not substantially uniform, with the higher molecular weight fractions having proportionally higher comonomer content (i.e., if comonomer incorporation increases with molecular weight, the distribution is described as "reverse" or "reversed"). If comonomer incorporation increases and then decreases with increasing molecular weight, the comonomer distribution is still considered "reverse," but may be described as "partially reversed."

[0134] In one embodiment, the ethylene copolymer contains catalyst residues that reflect the chemical composition of the catalyst formulation used to make it. Those skilled in the art will understand that catalyst residues are typically quantified in terms of parts per million of metal, for example, in the ethylene copolymer, where the metals present originate from the metals in the catalyst formulation used to make it. Non-limiting examples of metal residues that may be present include Group 4 to 6 metals, such as titanium, zirconium, hafnium, and vanadium.

[0135] In embodiments of the present disclosure, the ethylene copolymer has (based on the weight of the ethylene copolymer) at least 0.050 ppm titanium, or at least 0.100 ppm titanium, or at least 0.250 ppm titanium, or at least 0.300 ppm titanium.

[0136] In embodiments of the present disclosure, the ethylene copolymer has (based on the weight of the ethylene copolymer) 0.050 to 3.0 ppm titanium, or 0.050 to 2.5 ppm titanium, or 0.050 to 2.0 ppm titanium, or 0.050 to 1.5 ppm titanium, or 0.050 to 1.0 ppm titanium, or 0.100 to 3.0 ppm titanium, or 0.100 to 2.5 ppm titanium, or 0.100 to 2.0 ppm titanium, or 0.100 to 1.5 ppm titanium, or 0.100 to 1.0 ppm titanium, or 0.250 to 3.0 ppm titanium, or 0.250 to 2.0 ppm titanium, or 0.250 to 1.5 ppm titanium, or 0.250 to 1.0 ppm titanium.

[0137] In embodiments of the present disclosure, the ethylene copolymer has at least 0.050 ppm vanadium, or at least 0.100 ppm vanadium, or at least 0.200 ppm vanadium, or at least 0.250 ppm vanadium, or at least 0.300 ppm vanadium (based on the weight of the ethylene copolymer).

[0138] In an embodiment of the present disclosure, the ethylene copolymer contains (by weight of the ethylene copolymer) 0.050 to 3.0 ppm vanadium, or 0.050 to 2.5 ppm vanadium, or 0.050 to 2.0 ppm vanadium, or 0.050 to 1.5 ppm vanadium, or 0.050 to 1.0 ppm vanadium, or 0.100 to 3.0 ppm vanadium, or 0 It has 0.100 to 2.5 ppm of vanadium, or 0.100 to 2.0 ppm of vanadium, or 0.100 to 1.5 ppm of vanadium, or 0.100 to 1.0 ppm of vanadium, or 0.200 to 3.0 ppm of vanadium, or 0.200 to 2.0 ppm of vanadium, or 0.200 to 1.5 ppm of vanadium, or 0.200 to 1.0 ppm of vanadium.

[0139] In one embodiment of the present disclosure, the ethylene copolymer has no long chain branching or does not contain measurable amounts of long chain branching ("LCB"). LCB is a well-known structural phenomenon in ethylene copolymers and is familiar to those skilled in the art. Traditionally, there are three methods for LCB analysis: nuclear magnetic resonance spectroscopy (NMR) (see, e.g., J.C.Randall, J. Macromol. Sci., Rev., Macromol. Chem. Phys., 1989, Vol. 29, p. 201); triple-detection SEC with DRI, viscometer, and low-angle laser light scattering detector (see, e.g., W.W. Yau and D.R. Hill, Int. J. Polym. Anal. Character., 1996, Vol. 2, p. 151); and rheology (see, e.g., W.W. Graessley, Acc. Chem. Res., 1977, Vol. 10, pp. 332-339).

[0140] In one embodiment of the present disclosure, the cellulose derivatives have an Mz of greater than about 500,000 and a molecular weight distribution (M) of about 9.0 to about 12.0. w / M n), and a melt index greater than 0.5 g / 10 min. Without wishing to be bound by theory, we have observed that these ethylene copolymer properties can be achieved using the multi-zone reactor system described above and by carefully manipulating the amount and location of hydrogen addition throughout the multi-zone reactor system, as shown in the accompanying examples.

[0141] <Biaxial orientation process> In one embodiment of the present disclosure, a biaxially oriented polyethylene film or biaxially oriented polyethylene film structure comprises an ethylene copolymer made according to the present disclosure.

[0142] Biaxially oriented polyethylene (BOPE) films or film structures can be made using a tenter frame process in one embodiment of the present disclosure.

[0143] The tenterframe process is commonly used to prepare biaxially oriented films and is suitable for the present invention. The tenterframe process is well known to those skilled in the art of film manufacturing. The process begins with an extruder equipped with a slot die to form a sheet or film. For convenience, this extruded sheet or film may be referred to as the "base film" or "base film structure" or "base structure." Once the base structure is quenched on a chill roll, machine direction (MD) stretching or machine direction orientation (MDO) is achieved by pulling the base structure using several rotating rolls with gradually increasing surface speeds. Following MD stretching, clips (attached to chains) grip the edges of the moving sheet (or film, or web) and transport it to an oven. Within the oven, the edges of the base structure are pulled apart, widening the sheet and providing transverse direction orientation (TDO). This orientation / stretching thins the film structure in proportion to the orientation ratio or stretch ratio. For example, to prepare a 1 mil finished BOPE film with a 5:1 stretch ratio in the machine direction (MD) and an 8:1 stretch ratio in the transverse direction (TD), one must begin the process with a 40 mil thick film or sheet. Note that in embodiments of the present disclosure, the machine direction (MD) stretch ratio may range from about 5:1 to about 9:1, and the transverse direction (TD) stretch ratio may range from about 7:1 to 12:1. Further details are provided in the textbook "Film Processing Advances" (Kanai et al., 2014, Hanser Publishers).

[0144] Biaxial orientation can improve the toughness, barrier properties, optical properties, heat resistance, and stiffness of the film. However, conventional polyethylene is generally considered to be less suitable for tenterframe processes because it can have poorer stretchability compared to, for example, polypropylene (PP) or polyethylene terephthalate (PET).

[0145] In one embodiment, the ethylene copolymers made in accordance with the present disclosure are used to make BOPE films or film structures.

[0146] In one embodiment, a BOPE film or film structure is made with 60-100 wt% ethylene copolymer made in accordance with the present disclosure. In one embodiment, a BOPE film or film structure is made with 70-90 wt% ethylene copolymer made in accordance with the present disclosure. In one embodiment, a BOPE film is made with 80-95 wt% ethylene copolymer made in accordance with the present disclosure.

[0147] In one embodiment, a BOPE film or film structure is made using 60-100 wt% of an ethylene copolymer made in accordance with the present disclosure, with the remaining polymer used to make the BOPE film or film structure also being polyethylene. In one embodiment, a BOPE film or film structure is made using 70-90 wt% of an ethylene copolymer made in accordance with the present disclosure, with the remaining polymer used to make the BOPE film or film structure also being polyethylene. In one embodiment, a BOPE film is made using 80-95 wt% of an ethylene copolymer made in accordance with the present disclosure, with the remaining polymer used to make the BOPE film or film structure also being polyethylene. Without wishing to be bound by theory, preparing a BOPE film or film structure using only polyethylene may allow the film to be more easily recycled compared to films made with a blend of polymers.

[0148] The use of blends of polymers is known in the art for preparing BOPE films, and is also contemplated in certain embodiments of the present disclosure. Thus, in one embodiment of the present disclosure, a BOPE film or film structure is prepared from a polymer blend composition comprising at least 60 wt.% of an ethylene copolymer made according to the present disclosure.

[0149] Some non-limiting examples of other polymers suitable for use in blends with ethylene copolymers in embodiments of the present disclosure include: linear low density polyethylene (LLDPE); medium density polyethylene (MDPE); high density polyethylene (HDPE); very low density polyethylene (VLDPE), including elastomers and plastomers; and high pressure low density polyethylene (HPLDPE), which is prepared by free radical polymerization of ethylene.

[0150] In an embodiment of the present disclosure, the LLDPE used in the polymer blend with the ethylene copolymer has a melt index (I2) of 0.1 to 10 g / 10 min, or 0.9 to 2.3 g / 10 min, and a melt index (I2) of about 0.910 to about 0.935 g / cm 3 It has a density of

[0151] In embodiments of the present disclosure, the VLPDE used in the polymer blend with the ethylene copolymer has a melt index (I2) of 0.1 to 10 g / 10 min, or 0.9 to 2.3 g / 10 min, and a melt index (I2) of about 0.890 to about 0.910 g / cm 3 It has a density of

[0152] In an embodiment of the present disclosure, the MDPE used in the polymer blend with the ethylene copolymer has a melt index (I2) of 0.1 to 10 g / 10 min, or 0.9 to 2.3 g / 10 min, and a melt index (I2) of about 0.936 to about 0.949 g / cm 3 It has a density of

[0153] In an embodiment of the present disclosure, the HDPE used in the polymer blend with the ethylene copolymer has a melt index (I2) of 0.1 to 10 g / 10 min, or 0.4 to 0.9 g / 10 min, and a melt index (I2) of at least about 0.95 g / cm 3 It has a density of

[0154] In one embodiment of the present disclosure, the HPLDPE used in the polymer blend with the ethylene copolymer has a melt index (I2) of 0.1 to 10 g / 10 min and a melt index (I2) of about 0.92 to about 0.94 g / cm 3 It has a density of

[0155] In the art of preparing BOPE films, it is known to use a multilayer film or film structure as the starting (unstretched) film. These starting films are relatively thick before being stretched and are often referred to as "sheets" rather than films. For convenience, such unstretched multilayer sheets are sometimes referred to as "base films" or "base film structures" or "base structures."

[0156] In one embodiment of the present disclosure, a suitable base film structure comprises at least 60 wt. % (based on the total weight of the base film structure) of an ethylene copolymer made as described herein.

[0157] In one embodiment of the present disclosure, the ethylene copolymers prepared as described herein are used as the "core" layer in a suitable base film structure (i.e., as an inner layer in a multi-layer base film structure).

[0158] Examples of polymers that can be used to prepare the other layers include the LLDPE, MDPE, HDPE, VLPDE and HPLDPE mentioned above.

[0159] In one embodiment of the present disclosure, the multilayer base film structure comprises at least three layers, including two skin layers (ie, layers on each outer surface of the base film structure) and one or more core layers.

[0160] In one embodiment of the present disclosure, one skin layer can be made from HDPE and the other skin layer is a sealing layer, as disclosed in published US Pat. No. 9,676,169.

[0161] In one embodiment of the present disclosure, the sealing layer may comprise linear low density polyethylene, LLDPE (such as so-called metallocene-catalyzed LLDPE, which is well known to those skilled in the art), plastomer, elastomer, or blends thereof.

[0162] In one embodiment, plastomers comprising polymerized ethylene and 1-octene monomers (and blends thereof with LLDPE, HDPE and / or HPLDPE) may also be used in the seal layer.

[0163] In one embodiment of the present disclosure, it is also contemplated to use a plastomer (or polymer blends thereof) in both skin layers of the BOPE film.

[0164] Without wishing to be bound by theory, the use of plastomers in the skin layers may improve the optical properties of BOPE films.

[0165] In one embodiment of the present disclosure, a BOPE film has a core layer comprising an ethylene copolymer made as described herein, and both skin layers comprise a plastomer comprising polymerized ethylene and 1-octene monomers.

[0166] In one embodiment of the present disclosure, the BOPE film has a core layer comprising an ethylene copolymer made as described herein, and both skin layers also comprise an ethylene copolymer made as described herein.

[0167] In one embodiment of the present disclosure, a multilayer structure comprising at least five layers has two outer skin layers made from a plastomer and two "adjacent to the skin" layers made from a blend of plastomer and polyethylene of higher density than the plastomer.

[0168] It is known to use a layer of "barrier resin" to improve the barrier properties of BOPE films. Non-limiting examples of suitable barrier resins include ethylene vinyl alcohol (EVOH) and polyamides.

[0169] Polymers used in the present disclosure (including ethylene copolymers prepared as described herein) may, in certain embodiments, contain an antioxidant (such as a hindered phenol, a phosphite, or a blend of both) in conventional amounts, as will be familiar to those skilled in the art. Other optional additives that may be added to polymers (including ethylene copolymers prepared as described herein) in certain embodiments include antiblocking agents, slip agents, and nucleating agents (such as those disclosed in U.S. Pat. No. 9,676,169). Zinc glycerolate is also contemplated as an optional nucleating agent for use in certain embodiments of the present disclosure (Note: zinc glycerolate nucleating agent is commercially available under the trademark IRGASTAB® 287).

[0170] BOPE films prepared according to the present disclosure may be suitable for use in a wide variety of packaging applications. In one embodiment, the BOPE film can be used in a laminate structure; for example, the BOPE film can be used as a printing web when laminated to a sealant web made from a lower density polyethylene. This type of laminate structure can be more easily recycled compared to conventional laminate structures that include a layer of polyester or polypropylene laminated to a layer of polyethylene.

[0171] The following examples are presented for the purpose of illustrating selected embodiments of the present disclosure, with the understanding that the presented examples do not limit the scope of the presented claims. [Example]

[0172] <Polymer Characterization and Testing Methods> Prior to testing, each polymer specimen was conditioned at 23±2°C and 50±10% relative humidity for at least 24 hours, with subsequent testing being performed at 23±2°C and 50±10% relative humidity. As used herein, the term "ASTM conditions" refers to a laboratory maintained at 23±2°C and 50±10% relative humidity, and the specimens to be tested were conditioned in this laboratory for at least 24 hours prior to testing. ASTM refers to American Society for Testing and Materials.

[0173] <density> The density of polymers (e.g., ethylene copolymers) was determined using ASTM D792-13 (November 1, 2013).

[0174] <Melt index and stress index> The melt index of ethylene copolymers was determined using ASTM D1238 (August 1, 2013). Melt index, I2, I6, I 10 , and I 21 were measured at 190°C using weights of 2.16 kg, 6.48 kg, 10 kg, and 21.6 kg, respectively. As used herein, the term "stress index" or its acronym "S.Ex." is defined by the following relationship: S.Ex.=log(I6 / I2) / log(6480 / 2160) (where I6 and I2 are the melt flow rates measured at 190°C using loads of 6.48 kg and 2.16 kg, respectively).

[0175] <Neutron activation (elemental analysis)> Neutron activation analysis (NAA) was used to determine catalytic metal residues in ethylene copolymers as follows: A radioactive vial (composed of ultra-high purity polyethylene, with an internal volume of 7 mL) was filled with an ethylene copolymer composition sample, and the sample weight was recorded. Using a pneumatic transfer system, the sample was placed in a SLOWPOKE™ reactor (Atomic Energy of Canada Limited, Ottawa, Ontario, Canada) and irradiated for 30-600 seconds for short-half-life elements (e.g., Ti, V, Al, Mg, and Cl) or 3-5 hours for long-half-life elements (e.g., Zr, Hf, Cr, Fe, and Ni). The average thermal neutron flux in the reactor was 5 × 10 11 / cm 2 / s. After irradiation, the samples were removed from the reactor and aged to allow the radioactivity to decay. Short-half-life elements were aged for 300 seconds, and long-half-life elements were aged for several days. After aging, the gamma-ray spectrum of the sample was recorded using a germanium semiconductor gamma-ray detector (Ortec model GEM55185, Advanced Measurement Technology Inc., Oak Ridge, TN, USA) and a multichannel analyzer (Ortec model DSPEC Pro). The amount of each element in the sample was calculated from the gamma-ray spectrum and recorded in parts per million relative to the total weight of the ethylene copolymer composition sample. The NAA system was calibrated with Specpure standards (1000 ppm solutions of the desired elements (greater than 99% purity)). 1 mL of the solution (element of interest) was pipetted onto a 15 mm × 800 mm rectangular paper filter and air-dried. The filter paper was then placed in a 1.4 mL polyethylene irradiation vial and analyzed with the NAA system. The standards are used to determine the sensitivity of the NAA procedure (counts / µg).

[0176] <Gel Permeation Chromatography (GPC)> Ethylene copolymer sample (polymer) solutions (1–3 mg / mL) were prepared by heating the polymer in 1,2,4-trichlorobenzene (TCB) and rotating it on a wheel in an oven at 150 °C for 4 hours. To stabilize the polymer against oxidative degradation, an antioxidant (2,6-di-tert-butyl-4-methylphenol (BHT)) was added to the mixture. The BHT concentration was 250 ppm. The polymer solution was chromatographed at 140 °C in a PL220 high-temperature chromatography unit equipped with four SHODEX® columns (HT803, HT804, HT805, and HT806) using TCB as the mobile phase at a flow rate of 1.0 mL / min and differential refractive index (DRI) as the concentration detector. To protect the GPC column from oxidative degradation, BHT was added to the mobile phase at a concentration of 250 ppm. The sample injection volume was 200 μL. The GPC column was calibrated with narrow-distribution polystyrene standards. Polystyrene molecular weights were converted to polyethylene molecular weights using the Mark-Houwink equation as described in ASTM Standard Test Method D6474-12 (December 2012). GPC raw data were processed with CIRRUS GPC software to obtain molar mass averages (M n , M w , M z ) and molar mass distribution (e.g., polydispersity, M w / M n In the polyethylene art, the commonly used term equivalent to GPC is SEC, or size exclusion chromatography.

[0177] <gpc-ftir> Ethylene copolymer (polymer) solutions (2–4 mg / mL) were prepared by heating the polymer in 1,2,4-trichlorobenzene (TCB) and rotating it on a wheel in an oven at 150 °C for 4 hours. An antioxidant (2,6-di-tert-butyl-4-methylphenol (BHT)) was added to the mixture to stabilize the polymer against oxidative degradation. The BHT concentration was 250 ppm. The sample solution was chromatographed at 140 °C using TCB as the mobile phase at a flow rate of 1.0 mL / min on a Waters GPC 150C chromatography unit equipped with four SHODEX columns (HT803, HT804, HT805, and HT806). The detection system consisted of an FTIR spectrometer and a heated FTIR flow-through cell connected to the chromatography unit via a heated transfer line. To protect the SEC column from oxidative degradation, BHT was added to the mobile phase at a concentration of 250 ppm. The sample injection volume was 300 μL. The raw FTIR spectra were processed using OPUS® FTIR software, and polymer concentration and methyl content were calculated in real time using the OPUS-associated Chemometric software (PLS technique). Polymer concentration and methyl content were then acquired and baseline corrected using CIRRUS GPC software. The SEC column was calibrated with narrow-dispersion polystyrene standards. Polystyrene molecular weights were converted to polyethylene molecular weights using the Mark-Houwink equation, as described in ASTM standard test method D6474. Comonomer content was calculated based on polymer concentration and methyl content predicted by PLS technique, as described in Paul J. DesLauriers, Polymer 43, pages 159-170 (2002); incorporated herein by reference.

[0178] <Short Chain Branching: GPC-FTIR> The short-chain branches per 1000 carbon atoms are measured for copolymer fractions with different molecular weights. When plotted on a semi-logarithmic graph, the sloping line (logarithmic horizontal x-axis from low to high molecular weight fractions and vertical y-axis representing the number of short-chain branches) represents the distribution of short-chain branches for the different molecular weight fractions as determined by Fourier transform infrared (FTIR) spectroscopy. The GPC-FTIR method measures the total methyl content, including the methyl groups located at the end of each polymer chain, i.e., the methyl end groups. Therefore, the raw GPC-FTIR data must be corrected by subtracting the contribution from the methyl end groups. More specifically, the raw GPC-FTIR data overestimate the amount of short-chain branches (SCB), and this overestimation increases as the molecular weight (M) decreases. In this disclosure, the raw GPC-FTIR data was corrected using the 2-methyl correction. At a given molecular weight (M), the total methyl end groups (N E ) is calculated using the following formula: N E = 28000 / M, calculated using N E (M dependent) was subtracted from the raw GPC-FTIR data to generate SCB / 1000C (2-methyl corrected) GPC-FTIR data.

[0179] <Differential scanning calorimetry (DSC)> DSC testing was performed according to ASTM D3418. The analysis was performed by subjecting a polymer sample (5–10 mg prepared in an aluminum pan) and a reference material (an empty aluminum pan) to a constant temperature change in the DSC cell. The actual temperatures of the sample and reference material were monitored by the instrument as the sample temperature increased or decreased linearly with time. If the sample undergoes a transition, reaction, or transformation, its rate of temperature change will differ from that of the reference material. The instrument (TA Instruments Q2000) was first calibrated with indium. After calibration, the polymer specimen was equilibrated at 0°C, the temperature was increased to 200°C at a heating rate of 10°C / min, and the melt was then isothermally held at 200°C for 5 minutes. The melt was then cooled to 0°C at a cooling rate of 10°C / min and maintained at 0°C for 5 minutes. The specimen was then heated to 200°C at a heating rate of 10°C / min. The temperature difference between the sample and the reference (DT = Treference - Tsample) was then plotted against the temperature of the sample to generate a differential thermogram, from which the melting peak temperature (°C), melting enthalpy (J / g), and crystallinity (%) were determined.

[0180] <Dynamic mechanical analysis (DMA)> Oscillatory shear measurements at small strain amplitudes were performed at 190 °C under a N2 atmosphere, with a 10% strain amplitude and five points per 100 μm, to obtain linear viscoelastic functions over a frequency range of 0.02 to 126 rad / s. Frequency sweep experiments were performed on a TA Instruments DHR3 stress-controlled rheometer using a cone-plate geometry with a 5° cone angle, a 137 μm truncation, and a 25 mm diameter. In these experiments, a sinusoidal strain wave was applied, and the stress response was analyzed in terms of linear viscoelastic functions. Zero shear rate viscosity (η) based on the DMA frequency sweep results was predicted using the Ellis model (see R.B. Bird et al., "Dynamics of Polymer Liquids. Volume 1: Fluid Mechanics," Wiley-Interscience Publications, 1987, p. 228) or the Carreau-Yasuda model (see K. Yasuda, PhD Thesis, IT Cambridge, 1979).

[0181] <Capillary Rheology> Rheological data obtained from a Dynisco LCR7000 capillary rheometer was used to obtain viscosity profiles at different shear rates for different resins. In a capillary extrusion rheometer, the material is held in a temperature-controlled barrel and forced by a piston into a die of precise dimensions. The bore size, die size, and piston speed determine the apparent shear rate applied to the material, and the force and die size are used to calculate the apparent shear stress. Shear viscosity can be obtained from the capillary flow method using Poiseuille's law. TIFF0007787115000001.tif33156 Where P = pressure drop across the capillary (N / m 2 ); R = radius of the capillary (m); L = length of the capillary (m); Q = volumetric flow rate (m 3 / sec);σ s = apparent shear stress; ∂γ / (∂t) = apparent shear rate.

[0182] The shear rate, shear stress, and shear viscosity determined using the Poiseuille equation are usually referred to as apparent shear viscosity, apparent shear stress, and apparent shear rate. This is because the non-Newtonian properties of most fluids and the pressure drop at the die inlet and outlet pressures are not taken into account. The test temperature was set at 200°C. For this evaluation, the capillary length used was 30.48 mm, and the die diameter was 1.524 mm.

[0183] <Melt strength> Melt strength is measured using a Rosand RH-7 capillary rheometer (barrel diameter = 15 mm) with a 2 mm diameter flat die with an L / D ratio of 10:1 at 190°C. Pressure transducer: 10,000 psi (68.95 MPa). Piston speed: 5.33 mm / min. Take-off angle: 52°. Take-off incremental speed: 50-80 m / min. 2 or 65±15m / min 2 The polymer melt is extruded through a capillary die at a constant rate and then drawn at an increasing take-up speed until the polymer strand ruptures. The maximum stable value of the force in the plateau region of the force versus time curve is defined as the melt strength of the polymer.

[0184] <Vicat softening point (temperature)> The Vicat softening point of ethylene copolymer samples was determined in accordance with ASTM D1525-07, published December 2009. This test determines the temperature at which a specified needle penetration occurs when the sample is subjected to the test conditions of ASTM D1525-07, i.e., heating rate B (120±10°C / hr and 938 gram load (10±0.2 N load)).

[0185] <CYTSAF / TREF(CTREF)> The "Composition Distribution Breadth Index" (hereinafter CDBI) of ethylene copolymers (and comparative examples) was measured using a CRYSTAF / TREF200+ unit equipped with an IR detector (hereinafter CTREF). The acronym "TREF" stands for Temperature Rising Elution Fractionation. CTREF was provided by Polymer Characterization SA (Valencia Technology Park, Gustave Eiffel, 8, Paterna, E-46980 Valencia, Spain). The CTREF was operated in TREF mode, which allows the determination of the elution temperature, Co / Ho ratio (copolymer / homopolymer ratio), and CDBI (Composition Distribution Breadth Index), i.e., CDBI 50 and CDBI 25 The chemical composition of a polymer sample as a function of pH was calculated. A polymer sample (80–100 mg) was placed in a CTREF reaction vessel. 35 mL of 1,2,4-trichlorobenzene (TCB) was added to the reaction vessel, and the polymer was dissolved by heating the solution to 150 °C for 2 h. An aliquot (1.5 mL) of the solution was then loaded onto a CTREF column packed with stainless steel beads. The sample-loaded column was then stabilized at 110 °C for 45 min. The polymer was then crystallized from the solution in the column by lowering the temperature to 30 °C at a cooling rate of 0.09 °C / min. The column was then equilibrated at 30 °C for 30 min. The crystallized polymer was then eluted from the column while TCB was flowed through the column at 0.75 mL / min, and the column was slowly heated from 30 °C to 120 °C at a heating rate of 0.25 °C / min. Raw CTREF data were processed using Polymer ChAR software, an Excel spreadsheet, and in-house developed CTREF software. 50 is defined as the percentage of polymers whose composition is within 50% of the median central comonomer composition; 50 was calculated from the composition distribution curve and the normalized cumulative integral of the composition distribution curve, as described in U.S. Patent No. 5,376,439. Those skilled in the art will understand that a calibration curve is required to convert the CTREF elution temperature to comonomer content, i.e., the amount of comonomer in the ethylene / α-olefin polymer fraction eluting at a particular temperature. The construction of such a calibration curve is described in the prior art, for example, Wild et al., J. Polym. Sci., Part B, Polym. Phys., Vol. 20(3), pp. 441-455, which is incorporated herein by reference in its entirety. CDBI calculated in a similar manner 25 ;CDBI 25 is defined as the percentage of polymers whose composition is 25% of the median central comonomer composition. At the end of each sample run, the CTREF column was cleaned for 30 minutes by bringing the temperature of the CTREF column to 160°C and running TCB (0.5 mL / min) through the column for 30 minutes.

[0186] <Film Optics> Film optical properties (of the base unstretched multilayer precursor film and the stretched multilayer film) were measured as follows: haze, ASTM D1003-13 (November 15, 2013), and 45° gloss, ASTM D2457-13 (April 1, 2013).

[0187] <Film Elmendorf tear resistance> Film tear performance (of the base unstretched multilayer precursor film and the stretched multilayer film) was determined according to ASTM D1922-09 (May 1, 2009), the equivalent term for tear being "Elmendorf tear." Film tear was measured in both the machine direction (MD) and transverse direction (TD) for blown films.

[0188] <Mechanical properties> Tensile tests in both the machine and transverse directions (MD and TD, respectively) were performed according to ASTM D882. The specimen width used for tensile property measurements was 1.0 inch. The initial extension rate was 1.0 inch / min to 5% strain, then the rate was increased to 20.0 inch / min until break. The grip spacing was 2.0 inches. The mechanical properties measured were tensile stress at break (reported in MPa), strain at yield (%), yield stress (MPa), strain at break (%), and stress at break (MPa). The 1% and 2% secant moduli (MPa) are measured using 1.0 inch wide specimens with a 2 inch grip spacing at a test speed of 1.0 inch / min.

[0189] <Water vapor transmission rate (WVTR)> Water Vapor Transmission Rate ("WVTR"), grams of water vapor per 100 square inches of film per day for a specific film thickness (mils), or g / 100in 2 / day) was measured in accordance with ASTM F1249-90 using an instrument sold under the name Ametek by MOCON (Minneapolis, USA). The test was carried out at 100°F (37.8°C) and 100% relative humidity.

[0190] <Oxygen transmission rate (OTR)> Oxygen Transmission Rate ("OTR") per 100 inches per day at a given film thickness (mils) 2 per cm 2 ) was measured according to ASTM D3985-17 using an instrument sold under the name Ametek by MOCON (Minneapolis, USA). Testing was performed at 23°C, 0% relative humidity, and 1 atmosphere pressure. A mixture of 98% nitrogen (N2) and 2% hydrogen (H2) was used as the carrier gas, and 100% oxygen (O2) was used as the test gas. Testing was terminated when the oxygen flux changed by less than 1% over the 15-minute test cycle. Reported data were normalized (multiplied) by film thickness and are the average of four tests.

[0191] <Puncture resistance> Film puncture resistance (of the base unstretched precursor multilayer film as well as the stretched multilayer film) was measured in terms of film puncture (J / mm) according to ASTM D5748-95. Film displacement was recorded versus force (lb), and the maximum force was reported as puncture force (lb) at break according to ASTM D5748-95.

[0192] <Film thickness> The film thickness of the base unstretched precursor multilayer film and the stretched multilayer film was measured according to ASTM D6988-13.

[0193] <Polymerization process> Ethylene copolymers were prepared in a multi-zone solution polymerization process in which three polymerization zones, each defined by a different polymerization reactor, were arranged in series with one another (see Figure 1). The first polymerization zone was defined by a first tubular reactor (Reactor 1), the second polymerization zone was defined by an optionally stirred tank reactor (Reactor 2), and the third polymerization zone was defined by a second tubular reactor (Reactor 3). Each reactor had an inlet through which the process flow entered the reactor and an outlet through which the process flow exited the reactor. For the tubular reactors, the inlet was located at the upstream end of the reactor and the outlet was located at the downstream end of the reactor. In this polymerization process, the tank reactor (Reactor 2) receiving the process flow from the first tubular reactor was a stirred tank reactor, optionally with an agitator present, but was operated without agitation and thus functioned as a type of plug flow reactor. Thus, in this disclosure, a tank reactor optionally equipped with an agitator is said to be operating in "plug flow mode" when the agitator is turned off.

[0194] The first tubular reactor (Reactor 1) was a 6-inch diameter, 36.6-meter long, 500-liter total volume pipe. The polymerization reaction was initiated by injecting a Ziegler-Natta polymerization catalyst into the reactor inlet (position A in Figure 1) along with solvent (cyclohexane), hydrogen, ethylene, and 1-butene. (Note: The Ziegler-Natta polymerization catalyst components were combined immediately upstream of the first tubular reactor inlet, as described further below; not shown in Figure 1). Hydrogen was also fed into a second position (position B in Figure 1) downstream from the first tubular reactor inlet and approximately 50% along the length of the first tubular reactor. In this solution phase polymerization process, as the process flow moved from the first tubular reactor into the tank reactor and then into the second tubular reactor, the polymerization reaction continued throughout the length of the first tubular reactor, continued in the tank reactor (Reactor 2), and then continued throughout the length of the second tubular reactor. The polymerization reaction temperature profile was monitored using eight temperature indicators located along the first tubular reactor.

[0195] Reactor 2 was a 3,640-liter tank (or "autoclave") reactor protected by a safety valve set at 19.1 MPa. The tank reactor was constructed of carbon steel, with a Monel-plated inlet nozzle. Four 11.4-cm-wide baffles were positioned vertically at 90° angles to each other, 6.35 cm from the wall, to prevent circulation within the vessel caused by the presence of the agitator. The agitator had five hubs, each with six impeller blades, evenly spaced across the height of the reactor. The tank reactor agitator was not used during this solution-phase polymerization process (it was present but not turned on), and therefore the tank reactor was operated in "plug flow mode." Temperature indicators located throughout the tank reactor were used to monitor the polymerization reaction temperature profile. The tank reactor was also traced with high-pressure steam.

[0196] Reactor 3 was a second tubular reactor with a 10 inch diameter pipe and was 53 meters long. Temperature indicators located throughout the tank reactor were used to monitor the polymerization reaction temperature profile.

[0197] The polymerization in the solution polymerization process was terminated by adding a catalyst deactivator to the outlet stream leaving the outlet of the second tubular reactor (Reactor 3). The catalyst deactivator used was pelargonic acid.

[0198] A solution absorbent (activated aluminum) is used to remove traces of metal residues (vanadium and zirconium) from Ziegler-Natta catalysts.

[0199] A two-stage devolatilization process was employed to recover the ethylene copolymer from the process solvent: two vapor / liquid separators were used, and the second bottoms stream (from the second V / L separator) was passed through a gear pump / pelletizer combination.

[0200] DHT-4V (hydrotalcite) supplied by Kyowa Chemical Industry Co., Ltd. (Tokyo, Japan) can be used as a passivator or acid scavenger in solution processes. A slurry of DHT-4V in the process solvent may be added before the first V / L separator.

[0201] The resin product is pelletized in two single screw extruders, followed by deactivation of the pellets in a nitrogen and steam supplied stripper.

[0202] Prior to pelletizing, the ethylene copolymer was stabilized by adding 1000 ppm IRGANOX® 1010 (primary antioxidant) and 1,000 ppm IRGAFOS® 168 (secondary antioxidant), based on the weight of the ethylene copolymer composition. The antioxidants were dissolved in process solvent and added between the first and second V / L separators.

[0203] The Ziegler-Natta polymerization catalyst used to carry out the polymerization reaction was fed into the inlet of the first tubular reactor and consisted of the following three components: (i) a vanadium precatalyst compound, VOCl3; (ii) titanium precatalyst component titanium tetrachloride, TiCl4; (iii) The cocatalyst compound triethylaluminum, (C2H5)3Al. The VOCl and TiCl compounds were first mixed (in cyclohexane) in an 80 / 20 weight ratio and then mixed with triethylaluminum immediately prior to injection into the first tubular reactor at its inlet (position A in Figure 1).

[0204] Details of solution phase polymerizations carried out in a multi-zone reaction system according to the present disclosure are set forth in Table 1. Details of ethylene copolymers made according to the present disclosure, along with comparative ethylene copolymers, are set forth in Table 2. The comparative ethylene copolymer "Comparative Example 3" is an ethylene / 1-hexene copolymer made in a gas phase process using a chromium catalyst and is available from NOVA Chemicals Corporation as HF-Y450-A.

[0205] Further details of ethylene copolymers made in accordance with the present disclosure and comparative examples are shown in Figures 2-7.

[0206] [Table 1]

[0207] [Table 2]

[0208] The data in Table 2, together with Figure 2, demonstrate that the ethylene copolymers made in accordance with the present disclosure (Inventive Examples 1 and 2) have broad molecular weight distributions (i.e., relatively high Mw / Mn) and a moderately high molecular weight tail, characteristics also observed in the comparative resin made in the gas phase (Comparative Example 3) and known to be useful in preparing BOPE films. Although the ethylene copolymers of the present disclosure (Inventive Examples 1 and 2) have broad molecular weights and a relatively high molecular weight tail, they nevertheless have higher melt indices, I2, than the comparative resin (Comparative Example 3). The comparative resin also has a very high molecular weight tail (see the relatively high Mz value for Comparative Example 3 in Figure 2 and Table 2), higher than that observed for ethylene copolymers made in accordance with the present disclosure. Without wishing to be bound by theory, such a very high molecular weight tail may contribute to gel formation during the preparation of BOPE films.

[0209] As shown in Figure 3, ethylene copolymers made in accordance with the present disclosure (Inventive Examples 1 and 2) generally exhibit a decreasing amount of short chain branches (branches per 1000 carbon backbone atoms) as the molecular weight of the ethylene copolymer increases.

[0210] As shown in Figure 4, the CTREF profiles of the ethylene copolymers made according to the present disclosure (Invention Examples 1 and 2) are similar to those obtained for the comparative resin (Comparative Example 3) made in the gas phase, which is known to be useful in making BOPE films. The similar CTREF profiles indicate that the resins of the invention examples and the comparative resins have similar amounts of amorphous (non-crystalline) polymer phase. Without wishing to be bound by theory, it is believed that the presence of an appropriate amount of amorphous, non-crystalline polymer phase aids in stretching the base film during the BOPE process by expanding the processing window (e.g., broadening the range of conditions under which the film can be successfully stretched). The presence of amorphous material can allow the sheet or film to soften, facilitating stretching before rapid melting of the crystalline phase occurs, widening the stretching window. Amorphous material can also make the sheet or film elastic during the stretching process, which promotes some strain hardening and results in uniform thickness during the stretching process.

[0211] As shown in Figure 5, the ethylene copolymers made according to the present disclosure (Inventive Examples 1 and 2) have slightly lower melting point temperatures than those obtained for the comparative resin made in the gas phase (Comparative Example 3). Without wishing to be bound by theory, a lower melting point of the polymer may be beneficial during the biaxial orientation process to make BOPE film structures; a lower melting point indicates the presence of more amorphous material in the polymer, which helps to soften the polymer sheet or film earlier during the orientation process, improving the orientation window.

[0212] Figure 6 shows that the ethylene copolymers prepared according to the present disclosure, Invention Examples 1 and 2, have good apparent shear viscosities and high shear thinning behaviors. For both Invention Examples 1 and 2, good shear thinning behaviors have been demonstrated, and Invention Examples 1 and 2 have similar molecular weight distributions (Mw / Mn) and similar melt flow ratios (I 21 / I2), but have somewhat different melt index I2 values. Without wishing to be bound by theory, good shear thinning behavior can provide a high production rate during the extrusion process for producing a BOPE film in a tenter frame process.

[0213] Figure 7 shows that the ethylene copolymers (Invention Examples 1 and 2) prepared according to the present disclosure have lower viscosities compared to the comparative resin (Comparative Example 3) prepared in the gas phase. Without wishing to be bound by theory, the lower polymer viscosity may help to improve the production rate during the extrusion process for producing a BOPE film in a tenter frame process.

[0214] <Preparation of BOPE Film> A biaxially oriented polyethylene (BOPE) film was prepared by a tenter frame process using the conditions described below.

[0215] <A. Preparation of Unstretched Film (or "Base Structure")> The multi-layer (3-layer) sheet is co-extruded from three single-screw extruders through a 12-inch casting die. The molten streams are combined within a feed block located in front of the casting die. The multi-layer sheet extruded from the die is secured to a cooling roll using an air knife and an edge pinner, and is rapidly cooled on the cooling roll. The primary cooling roll temperature was set at 65°C. For convenience, this unstretched multi-layer sheet may be referred to herein as the "base structure". The weight of the polymer used in each of the three layers is indicated in the form of A / B / C. For example, a base structure having two outer layers (or skin layers) each containing 10% by weight of the total polymer and a core layer containing 80% by weight of the total polymer is described as a 10 / 80 / 10 structure.

[0216] Using Invention Example 1 and Comparative Example 3, a 3-layer base film structure was prepared. That is, using the above-described procedure, Invention Example 1 or Comparative Example 3 was used for each of the A layer, B layer, and C layer to produce a 10 / 80 / 10 film structure.

[0217] From each of these base multi-layer film structures, a biaxially oriented polyethylene (BOPE) film was prepared using the procedure described in Part B below.

[0218] <B. Biaxial Orientation Process> In these examples, a sequential stretching process was used. First, stretching / orientation in the machine direction was performed. Then, the "oriented" sheet was stretched in the transverse direction.

[0219] Machine direction orientation (MDO) was performed using either a single-stage or multi-stage short-gap stretching process at a maximum temperature of 260°F and a maximum draw ratio of 7.5:1. Transverse direction orientation (TDO) was performed in a plurality of zones (a preheating zone, a stretching zone, an annealing zone, and finally one cooling zone). The temperature in the TDO stretching zone was a maximum of 270°F and the draw ratio was a maximum of 9:1.

[0220] MDO is achieved by preheating the base film and stretching the sheet between two rolls rotating at different speeds. The difference in roll speeds determines the stretch ratio. Stretching can be done with a single set of stretch rolls or on a series of stretch rolls. Stretching is generally done at a temperature below the crystalline melting temperature (Tm) of the film. The MDO film is then fed into a tenter frame oven using clips on chains attached to rails and preheated. As the rails move away from each other, the edges of the film are pulled, stretching the film, resulting in transverse stretching. The film width is set by the distance between the rails, which can be adjusted to achieve the desired stretch ratio. TDO is performed at temperatures equivalent to or slightly higher than MDO. Process conditions are summarized in Table 3.

[0221] [Table 3]

[0222] The properties of the BOPE multilayer films made from Inventive Example 1 or Comparative Example 3 are shown in Table 4. As shown in Table 4, a biaxially oriented polyethylene (BOPE) film was prepared from the 10 / 80 / 10 base structure of Inventive Example 1 with an MD stretch ratio of 6.5 and a TD stretch ratio of 9, while a biaxially oriented polyethylene (BOPE) film was prepared from the 10 / 80 / 10 base structure of Comparative Example 3 with an MD stretch ratio of 4.75 and a TD stretch ratio of 8.

[0223] [Table 4]

[0224] Inventive Example 1 has a density similar to Comparative Example 3, but a higher melt index I2 than Comparative Example 3, and was successfully stretched to make BOPE in a tenter frame process, as shown by the data in Table 4. Therefore, one skilled in the art would understand that an ethylene copolymer made according to the process of the present disclosure has a melt index of 0.940 to 0.960 g / cm3 suitable for use in making BOPE in a tenter frame process. 3 It will be appreciated that the present invention provides additional and alternative ethylene copolymers having densities in the range of

[0225] Non-limiting embodiments of the present disclosure include the following.

[0226] Embodiment A. An ethylene copolymer comprising ethylene and at least one alpha olefin having from 4 to 8 carbon atoms, having a viscosity of from 0.940 to 0.960 grams per cubic centimeter (g / cm 3 a melt index I2 of 0.5 to 2.5 grams per 10 minutes (g / 10 min), measured according to ASTM D1238 at 190°C using a 2.16 kilogram load; a stress index of 1.75 to 1.95; a number average molecular weight Mn of 11,000 to 15,000; a polydispersity index (Mw / Mn) of 9 to 12; and a Z-average molecular weight Mz of 500,000 to 800,000.

[0227] Embodiment B. Composition Distribution Breadth Index CDBI of 40 to 50 25 The ethylene copolymer of embodiment A, having

[0228] Embodiment C. The ethylene copolymer of embodiment A or B having a number average molecular weight, Mn, of 11,000 to 12,500.

[0229] Embodiment D. The ethylene copolymer of embodiment A or B having a number average molecular weight, Mn, of greater than 11,000 and less than 12,500.

[0230] Embodiment E. The ethylene copolymer of embodiment A, B, C, or D having a Z-average molecular weight, Mz, of 600,000 to 700,000.

[0231] Embodiment F. The ethylene copolymer of embodiment A, B, C, D, or E, further characterized by containing both titanium and vanadium catalyst residues in amounts (based on the weight of the ethylene copolymer) of 0.100 to 1.5 ppm titanium and 0.100 to 1.5 ppm vanadium.

[0232] Embodiment G. The ethylene copolymer of embodiment A, B, C, D, E or F having a monomodal molecular weight distribution.

[0233] Embodiment H: 0.940 to 0.956 g / cm 3 The ethylene copolymer of embodiment A, B, C, D, E, F, or G, having a density of

[0234] Embodiment I. The ethylene copolymer of embodiment A, B, C, D, E, F, G, or H having a stress index of 1.80 to 1.90.

[0235] Embodiment J. The ethylene copolymer of embodiment A, B, C, D, E, F, G, H or I comprising polymerized ethylene and 1-butene.

[0236] Embodiment K. A solution phase polymerization process for making ethylene copolymers in a multi-zone reactor system, comprising: The multi-zone reactor system includes first, second, and third polymerization zones, the first polymerization zone being defined by a first tubular reactor having an inlet and an outlet; The polymerization process comprises: feeding a solvent, hydrogen, a Ziegler-Natta polymerization catalyst, ethylene, and at least one alpha olefin having 4 to 8 carbon atoms into an inlet of a first tubular reactor to initiate a polymerization reaction; supplying hydrogen to at least one location within the first tubular reactor downstream from an inlet of the first tubular reactor; Including, at least 80 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor; 20 to 50 weight percent of the total amount of ethylene copolymer produced in the multi-zone reactor system is produced in the first tubular reactor; Solution phase polymerization process.

[0237] Embodiment L. The process of embodiment K, wherein the second polymerization zone is defined by a tank reactor having an inlet and an outlet.

[0238] Embodiment M. The process of embodiment K or L, wherein the third polymerization zone is defined by a second tubular reactor having an inlet and an outlet.

[0239] Embodiment N. The process of embodiment K, L, or M, wherein the at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor is at least one location within the first tubular reactor that is 35% to 65% downstream from the inlet along the length of the first tubular reactor.

[0240] Embodiment O. The process of embodiment K, L, or M, wherein the at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor is at least one location within the first tubular reactor that is 45% to 55% downstream from the inlet along the length of the first tubular reactor.

[0241] Embodiment P. The process of embodiment K, L, M, N, or O, wherein the tank reactor is operated as a plug flow reactor.

[0242] Embodiment Q. The process of embodiment K, L, M, N, O, or P, wherein the multi-zone reactor system is operated adiabatically.

[0243] Embodiment R. The process of embodiment K, L, M, N, O, P, or Q, wherein the inlet of the first tubular reactor is at a temperature of 30 to 150°C.

[0244] Embodiment S. The process of embodiment K, L, M, N, O, P, Q, or R, wherein the inlet to the first tubular reactor is at a temperature of less than 150°C.

[0245] Embodiment T. The process of any one of embodiments K, L, M, N, O, P, Q, R, or S, wherein at least 90 weight percent of the ethylene fed to the multi-zone reactor system is converted to ethylene copolymer.

[0246] Embodiment U. The process of embodiment K, L, M, N, O, P, Q, R, S, or T, wherein the Ziegler-Natta polymerization catalyst comprises titanium, vanadium, and aluminum.

[0247] Embodiment V. A solution phase polymerization process for making ethylene copolymers in a multi-zone reactor system, comprising: The multi-zone reactor system includes first, second, and third polymerization zones, the first polymerization zone being defined by a first tubular reactor having an inlet and an outlet; The polymerization process comprises: feeding a solvent, hydrogen, a Ziegler-Natta polymerization catalyst, ethylene, and at least one alpha olefin having 4 to 8 carbon atoms into an inlet of a first tubular reactor to initiate a polymerization reaction; supplying hydrogen to at least one location within the first tubular reactor downstream from an inlet of the first tubular reactor; Including, at least 80 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor; The ethylene copolymer has a viscosity of 0.940 to 0.960 grams per cubic centimeter (g / cm 3 a melt index I2 of 0.5 to 2.5 grams per 10 minutes (g / 10 min), measured according to ASTM D1238 at 190°C using a 2.16 kilogram load; a stress index of 1.75 to 1.95; a number average molecular weight Mn of 11,000 to 15,000; a polydispersity index (Mw / Mn) of 9 to 12; and a Z-average molecular weight Mz of 500,000 to 800,000, Solution phase polymerization process.

[0248] Embodiment W. A biaxially oriented polyethylene film comprising an ethylene copolymer, The ethylene copolymer comprises ethylene and at least one alpha olefin having 4 to 8 carbon atoms; The ethylene copolymer has a viscosity of 0.940 to 0.960 grams per cubic centimeter (g / cm 3 a melt index I2 of 0.5 to 2.5 grams per 10 minutes (g / 10 min), measured according to ASTM D1238 at 190°C using a 2.16 kilogram load; a stress index of 1.75 to 1.95; a number average molecular weight Mn of 11,000 to 15,000; a polydispersity index (Mw / Mn) of 9 to 12; and a Z-average molecular weight Mz of 500,000 to 800,000. [Industrial Applicability]

[0249] Ethylene copolymers are made in multi-zone reactor systems under solution phase polymerization conditions and are useful for forming biaxially oriented films. The content of the invention as claimed in the original patent application of this application is as follows: [Section 1] An ethylene copolymer comprising ethylene and at least one alpha olefin having 4 to 8 carbon atoms, 0.940 to 0.960 grams per cubic centimeter (g / cm 3 ) density; melt index I of 0.5 to 2.5 grams per 10 minutes (g / 10 min) measured at 190°C using a 2.16 kilogram load according to ASTM D1238 2 a stress index of 1.75 to 1.95; a number average molecular weight Mn of 11,000 to 15,000; a polydispersity index (Mw / Mn) of 9 to 12; and a Z average molecular weight Mz of 500,000 to 800,000. [Section 2] Composition Distribution Breadth Index (CDBI) of 40-50 25 Item 1. The ethylene copolymer according to item 1, having: [Section 3] Item 1. The ethylene copolymer according to item 1, having a number average molecular weight Mn of 11,000 to 12,500. [Section 4] Item 1. The ethylene copolymer according to item 1, having a number average molecular weight Mn of more than 11,000 and less than 12,500. [Section 5] Item 1. The ethylene copolymer according to item 1, having a Z-average molecular weight Mz of 600,000 to 700,000. [Section 6] Item 1. The ethylene copolymer of item 1, further characterized by containing both titanium and vanadium catalyst residues in amounts (based on the weight of the ethylene copolymer) of 0.100 to 1.5 ppm titanium and 0.100 to 1.5 ppm vanadium. [Section 7] Item 5. The ethylene copolymer according to item 1 or 4, having a monomodal molecular weight distribution. [Section 8] 0.940~0.956g / cm 3 Item 1. The ethylene copolymer according to item 1, having a density of [Section 9] Item 1. The ethylene copolymer according to item 1, having a stress index of 1.80 to 1.90. [Section 10] Item 1. The ethylene copolymer according to item 1, comprising polymerized ethylene and 1-butene. [Section 11] 1. A solution phase polymerization process for making ethylene copolymers in a multi-zone reactor system, comprising: The multi-zone reactor system includes first, second, and third polymerization zones, the first polymerization zone being defined by a first tubular reactor having an inlet and an outlet; The polymerization process comprises: feeding a solvent, hydrogen, a Ziegler-Natta polymerization catalyst, ethylene, and at least one alpha olefin having 4 to 8 carbon atoms into an inlet of a first tubular reactor to initiate a polymerization reaction; supplying hydrogen to at least one location within the first tubular reactor downstream from an inlet of the first tubular reactor; Including, at least 80 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor; The solution phase polymerization process wherein 20 to 50 weight percent of the total amount of ethylene copolymer produced in the multi-zone reactor system is produced in the first tubular reactor. [Section 12] Item 12. The process of item 11, wherein the second polymerization zone is defined by a tank reactor having an inlet and an outlet. [Section 13] Item 13. The process of paragraph 12, wherein the third polymerization zone is defined by a second tubular reactor having an inlet and an outlet. [Section 14] Item 14. The process of item 13, wherein the at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor is at least one location within the first tubular reactor that is 35% to 65% downstream from the inlet along the length of the first tubular reactor. [Section 15] Item 14. The process of item 13, wherein the at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor is at least one location within the first tubular reactor that is 45% to 55% downstream from the inlet along the length of the first tubular reactor. [Section 16] Item 14. The process of item 13, wherein the tank reactor is operated as a plug flow reactor. [Section 17] Item 14. The process of paragraph 13, wherein the multi-zone reactor system is operated adiabatically. [Section 18] Item 14. The process according to item 13, wherein the inlet of the first tubular reactor has a temperature of 30 to 150°C. [Section 19] Item 14. The process of item 13, wherein the inlet of the first tubular reactor is at a temperature of less than 150°C. [Section 20] 14. The process of claim 13, wherein at least 90 weight percent of the ethylene fed to the multi-zone reactor system is converted to ethylene copolymer. [Section 21] Item 14. The process of item 13, wherein the Ziegler-Natta polymerization catalyst comprises titanium, vanadium, and aluminum. [Section 22] 1. A solution phase polymerization process for making ethylene copolymers in a multi-zone reactor system, comprising: The multi-zone reactor system includes first, second, and third polymerization zones, the first polymerization zone being defined by a first tubular reactor having an inlet and an outlet; The polymerization process comprises: feeding a solvent, hydrogen, a Ziegler-Natta polymerization catalyst, ethylene, and at least one alpha olefin having 4 to 8 carbon atoms into an inlet of a first tubular reactor to initiate a polymerization reaction; supplying hydrogen to at least one location within the first tubular reactor downstream from an inlet of the first tubular reactor; Including, at least 80 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor; The ethylene copolymer has a viscosity of 0.940 to 0.960 grams per cubic centimeter (g / cm 3 ) density; melt index I of 0.5 to 2.5 grams per 10 minutes (g / 10 min) measured at 190°C using a 2.16 kilogram load according to ASTM D1238 2 a stress index of 1.75 to 1.95; a number average molecular weight Mn of 11,000 to 15,000; a polydispersity index (Mw / Mn) of 9 to 12; and a Z average molecular weight Mz of 500,000 to 800,000. [Section 23] 1. A biaxially oriented polyethylene film comprising an ethylene copolymer, The ethylene copolymer comprises ethylene and at least one alpha olefin having 4 to 8 carbon atoms; The ethylene copolymer has a viscosity of 0.940 to 0.960 grams per cubic centimeter (g / cm 3 ) density; melt index I of 0.5 to 2.5 grams per 10 minutes (g / 10 min) measured at 190°C using a 2.16 kilogram load according to ASTM D1238 2 a stress index of 1.75 to 1.95; a number average molecular weight Mn of 11,000 to 15,000; a polydispersity index (Mw / Mn) of 9 to 12; and a Z average molecular weight Mz of 500,000 to 800,000.

Claims

1. An ethylene copolymer comprising ethylene and at least one alpha olefin having 4 to 8 carbon atoms, The ethylene copolymer has a viscosity of 0.940 to 0.960 grams per cubic centimeter (g / cm ３ a melt index I of 0.5 to 2.5 grams per 10 minutes (g / 10 min), measured according to ASTM D1238 at 190° C. using a 2.16 kilogram load; ２ a stress index of 1.75 to 1.95; a number average molecular weight Mn of 11,000 to 15,000; a polydispersity index (Mw / Mn) of 9 to 12; a Z average molecular weight Mz of 500,000 to 800,000; a melt flow ratio I of greater than 60 ２１ / I ２ and a normal comonomer distribution profile as measured using GPC-FTIR, with Mn, Mz, and Mw / Mn determined by size exclusion chromatography at 140°C using ASTM D6474-12 on a PL220 high temperature chromatography unit equipped with four SHODEX columns (HT803, HT804, HT805, and HT806) using 1,2,4-trichlorobenzene as the mobile phase at a flow rate of 1.0 mL / min with differential refractive index (DRI) detection. The ethylene copolymer.

2. Composition Distribution Breadth Index (CDBI) of 40-50 ２５ 2. The ethylene copolymer of claim 1, having

3. 2. The ethylene copolymer of claim 1 having a number average molecular weight Mn of 11,000 to 12,500.

4. 2. The ethylene copolymer of claim 1 having a number average molecular weight Mn of greater than 11,000 and less than 12,500.

5. 2. The ethylene copolymer of claim 1 having a Z-average molecular weight Mz of 600,000 to 700,000.

6. 10. The ethylene copolymer of claim 1 further characterized by containing both titanium and vanadium catalyst residues in amounts (based on the weight of the ethylene copolymer) of 0.100 to 1.5 ppm titanium and 0.100 to 1.5 ppm vanadium.

7. 5. The ethylene copolymer of claim 1 or 4, having a monomodal molecular weight distribution.

8. 0.940~0.956g / cm ３ 2. The ethylene copolymer of claim 1 having a density of

9. 10. The ethylene copolymer of claim 1 having a stress index of 1.80 to 1.

90.

10. 10. The ethylene copolymer of claim 1 comprising polymerized ethylene and 1-butene.

11. 1. A solution phase polymerization process for making ethylene copolymers in a multi-zone reactor system, comprising: The multi-zone reactor system includes first, second, and third polymerization zones, the first polymerization zone being defined by a first tubular reactor having an inlet and an outlet; The polymerization process comprises: feeding a solvent, hydrogen, a Ziegler-Natta polymerization catalyst, ethylene, and at least one alpha olefin having 4 to 8 carbon atoms into an inlet of a first tubular reactor to initiate a polymerization reaction; supplying hydrogen to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor; Including, at least 80 weight percent of the total amount of hydrogen added to the multi-zone reactor system is added to at least one location within the first tubular reactor downstream from the inlet of the first tubular reactor; The ethylene copolymer has a viscosity of 0.940 to 0.960 grams per cubic centimeter (g / cm ３ a melt index I of 0.5 to 2.5 grams per 10 minutes (g / 10 min), measured according to ASTM D1238 at 190° C. using a 2.16 kilogram load; ２ a stress index of 1.75 to 1.95; a number average molecular weight Mn of 11,000 to 15,000; a polydispersity index (Mw / Mn) of 9 to 12; a Z average molecular weight Mz of 500,000 to 800,000; a melt flow ratio I of greater than 60 ２１ / I ２ and a normal comonomer distribution profile as measured using GPC-FTIR, with Mn, Mz, and Mw / Mn determined by size exclusion chromatography at 140°C using ASTM D6474-12 on a PL220 high temperature chromatography unit equipped with four SHODEX columns (HT803, HT804, HT805, and HT806) using 1,2,4-trichlorobenzene as the mobile phase at a flow rate of 1.0 mL / min with differential refractive index (DRI) detection. The solution phase polymerization process described above.

12. 1. A biaxially oriented polyethylene film comprising an ethylene copolymer, The ethylene copolymer comprises ethylene and at least one alpha olefin having from 4 to 8 carbon atoms; The ethylene copolymer has a viscosity of 0.940 to 0.960 grams per cubic centimeter (g / cm ３ a melt index I of 0.5 to 2.5 grams per 10 minutes (g / 10 min), measured according to ASTM D1238 at 190° C. using a 2.16 kilogram load; ２ a stress index of 1.75 to 1.95; a number average molecular weight Mn of 11,000 to 15,000; a polydispersity index (Mw / Mn) of 9 to 12; a Z average molecular weight Mz of 500,000 to 800,000; a melt flow ratio I of greater than 60 ２１ / I ２ and a normal comonomer distribution profile as measured using GPC-FTIR, with Mn, Mz, and Mw / Mn determined by size exclusion chromatography at 140°C using ASTM D6474-12 on a PL220 high temperature chromatography unit equipped with four SHODEX columns (HT803, HT804, HT805, and HT806) using 1,2,4-trichlorobenzene as the mobile phase at a flow rate of 1.0 mL / min with differential refractive index (DRI) detection. The biaxially oriented polyethylene film.

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