Process for producing polyolefins under compositional control

Abstract

A process for producing olefin copolymers, particularly ethylene-based copolymers. The process for producing olefin copolymers may include introducing an olefin monomer, at least one other olefin comonomer, and a single type of catalyst system into a tubular reactor to produce an olefin copolymer containing: a) an absolute comonomer distribution (CD) gradient 90 of about 2.0 to about 30.0, an absolute CD gradient 75 of about 2.0 to about 30.0, an absolute CD gradient 50 of about 2.0 to about 30.0, or an absolute CD gradient 25 of about 2.0 to about 30.0; b) a first long chain branching index (g'(Mz)) of about 0.30 to about 1.0; and c) a second long chain branching index (g'(Mz+1)) of about 0.30 to about 1.0. The tubular reactor may include one or more plug flow components, one or more spiral heat exchangers, and / or a recirculation pump.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 63 / 290,997, filed December 17, 2021, the disclosure of which is incorporated herein by reference in its entirety.

[0002] Field FIELD OF THE DISCLOSURE The present invention relates generally to processes for producing polyolefins and the polyolefins produced thereby. More particularly, the embodiments relate to processes for producing olefin copolymers, such as ethylene-based copolymers, using a single type of catalyst system and a single tubular reactor with control over the composition of those copolymers. [Background technology]

[0003] background Polyolefin homopolymers, copolymers, terpolymers, etc. can be produced using various types of catalyst systems and polymerization processes. One type of catalyst system that can be used to produce polyolefins is a metallocene-based catalyst system. Metallocene catalysts are homogeneous single-site catalysts that contain organometallic coordination compounds in which one or two cyclopentadienyl or substituted cyclopentadienyl rings are π-bonded to a central transition metal atom. Catalyst systems that contain single-site catalysts typically produce polyolefins with narrow molecular weight distributions and uniform comonomer distributions between chains, e.g., high molecular weight chains with low comonomer insertions and low molecular weight chains with high comonomer insertions.

[0004] Although polymers with narrow molecular weight distribution and uniform comonomer distribution along the polymer chain may be advantageous for certain processes and end uses, this type of polymer may be undesirable for other processes and applications. For example, narrow molecular weight distribution polymers may require the use of fluoropolymer additives to process the polymer at desired production rates without flow instabilities, such as melt fracture. Unfortunately, the use of fluoropolymer processing aids increases the cost of producing finished products from the polymer. Stability in other polymer processing operations, such as blown film and blow molding, is often lower for narrow molecular weight distribution polymers than for broader molecular weight distribution polymers, resulting in reduced production rates. Also, polymers with uniform comonomer distribution may have undesirable melt processability compared to polymers with broad comonomer distribution between different chains (also called normal composition distribution). Therefore, it is highly desirable to have the ability to control the molecular weight distribution and comonomer distribution of polymers produced using single-site catalysts.

[0005] Catalyst systems containing single-site catalysts can be used to produce polyolefins with a moderate amount of long-chain branching molecules. In some cases, long-chain branching is desirable to improve the processability of the resulting polymer. For example, the presence of long-chain branching can improve bubble stability during film blowing. However, in many end uses, a significant amount of long-chain branching can produce polymers that undesirably affect tear and tensile properties. Therefore, it is a desirable goal to have the ability to control the amount of long-chain branching in a polymer using catalyst systems containing single-site catalysts.

[0006] Other catalysts such as chromium or Ziegler-Natta (ZN) type catalysts can be used to produce polymers with broader molecular weight distributions. However, when utilizing either chromium or ZN catalysts, the use of hydrogen in the olefin polymerization process can cause narrowing of the molecular weight distribution and molecular weight degradation of the resulting polymer. Another drawback of using ZN catalysts is that the resulting polymers tend to end up with low molecular weights that are detrimental to the mechanical properties of the polymer. To overcome the challenges involved in using chromium or ZN catalysts, mixed metallocene-based catalyst systems have been developed that contain multiple metallocene catalysts that can be used to control the molecular weight distribution of the polymer. Methods of using two or more reactors with metallocene-based catalyst systems to control the molecular weight distribution have also been developed. However, both of these options are very expensive and are not typically achieved using solution polymerization processes. Also, these options do not provide effective control of molecular weight distribution, comonomer distribution, and long chain branching all at the same time. Thus, there is a need for a method for inexpensively producing polyolefins that utilizes catalyst systems and solution polymerization processes that include single-site catalysts while simultaneously controlling the molecular weight, comonomer distribution, and long chain branching of the resulting polymer. It would also be advantageous to have the ability to produce polymers with broad molecular weight distributions and broad comonomer distributions using single-site catalysts in the presence of hydrogen. Summary of the Invention

[0007] summary A process for producing olefin copolymers, particularly ethylene-based copolymers, is provided. In one or more embodiments, the process for producing an olefin copolymer may include introducing an olefin monomer, at least one other olefin comonomer, and a single type of single-site catalyst into a tubular reactor to produce an olefin copolymer containing: a) an absolute comonomer distribution (CD) gradient 90 of about 2.0 to about 30.0, an absolute CD gradient 75 of about 2.0 to about 30.0, an absolute CD gradient 50 of about 2.0 to about 30.0, or an absolute CD gradient 25 of about 2.0 to about 30.0; b) a first long chain branching index (g'(Mz)) of about 0.30 to about 1.0; and c) a second long chain branching index (g'(Mz+1)) of about 0.30 to about 1.0. The tubular reactor may include one or more plug flow elements, one or more heat exchangers, and at least one recirculation pump.

[0008] So that the above-mentioned features of the invention may be understood in detail, a more particular description of the invention briefly summarized above can be made with reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings merely illustrate typical embodiments of the invention and should not be considered as limiting the scope of the invention, since the invention may admit of other equally effective embodiments. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1a shows a tubular reactor containing a spiral heat exchanger arranged in a substantially vertical direction according to one or more embodiments provided herein, and FIG. 1b shows a plan view of the spiral heat exchanger of FIG. 1a. [Diagram 2] 1 shows a tubular reactor containing a spiral heat exchanger in a substantially horizontal orientation according to one or more embodiments provided herein. [Figure 3A] 1 is a graph showing molecular weight distribution and comonomer distribution along the polymer chain for an ethylene-octene copolymer according to one or more embodiments provided herein. [Figure 3B]3b is a graph showing the slope of the comonomer distribution profile of FIG. 3a according to one or more embodiments provided herein. [Figure 4] 1 is a graph showing a TREF distribution profile for the ethylene-octene copolymer according to one or more embodiments provided herein. [Figure 5A] 1 is a graph showing the slope of the comonomer distribution profile of additional ethylene-octene copolymers according to one or more embodiments provided herein. [Figure 5B] 1 is a graph showing TREF distribution profiles for additional ethylene-octene copolymers according to one or more embodiments provided herein. [Figure 6] 1 is a Van Gurp-Palmen plot showing complex modulus versus phase angle for additional ethylene-octene copolymers according to one or more embodiments provided herein. [Figure 7] 1 is a graph showing predicted versus observed Mw for ethylene-octene copolymers according to one or more embodiments provided herein. [Figure 8A] 1 is a graph showing observed and predicted comonomer distribution gradient 90 versus octene concentration for ethylene-octene copolymer production according to one or more embodiments provided herein. [Figure 8B] 1 is a graph showing observed and predicted comonomer distribution gradient 75 versus cement concentration for ethylene-octene copolymer production according to one or more embodiments provided herein. [Figure 9] 1 is a graph showing long chain branching index (g'(Mz)) versus ethylene concentration for ethylene-octene copolymer production according to one or more embodiments provided herein. [Figure 10] 1 is a graph showing molecular weight distribution and comonomer distribution along the polymer chain for an ethylene-butene copolymer according to one or more embodiments provided herein. [Figure 11]1 is a graph showing the average slope of comonomer distribution profile versus Mz / Mw value for ethylene-octene copolymers and ethylene-butene copolymers according to one or more embodiments provided herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Detailed Description It should be understood that the following disclosure describes several exemplary embodiments for implementing various features, structures, and / or functions of the present invention. The following describes exemplary embodiments of components, arrangements, and configurations to simplify the present disclosure. However, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the present invention. Furthermore, the present disclosure may repeat reference numbers and / or characters in various exemplary embodiments and throughout the figures provided herein. This repetition is for simplicity and clarity, and does not in itself dictate a relationship between the various exemplary embodiments and / or configurations discussed in the figures. Furthermore, the following exemplary embodiments may be used together in any combination manner. That is, any element of an exemplary embodiment may be used in any other exemplary embodiment without departing from the scope of the present disclosure. Additionally, certain terms are used throughout the following description and claims to refer to specific components. As will be apparent to one of ordinary skill in the art, various entities may refer to the same component by different names, and similarly, the naming conventions for the elements described herein are not intended to limit the scope of the invention unless specifically defined herein. Additionally, the naming conventions used herein are not intended to distinguish between components that differ in name but not function.

[0011] In the discussion below and in the claims, the terms "including" and "comprising" are used in an open-ended manner and should therefore be interpreted to mean "including, but not limited to." The phrase "consisting essentially of" means that the described and / or claimed composition does not contain any other components that would substantially alter its properties by more than 5%, and in any case does not contain any other components to a level of more than 3% by weight. The term "or" is intended to encompass both exclusive and inclusive cases, i.e., "A or B" is intended to be synonymous with "at least one of A and B," unless expressly specified otherwise in this specification. The indefinite articles "a" and "an" refer to both the singular (i.e., "one") and plural references (i.e., one or more), unless the context clearly dictates otherwise. For example, embodiments using "an olefin" include embodiments using one, two, or three or more olefins, unless specified to the contrary or the context clearly dictates that only one olefin is used. The term "wt%" means weight percentage, "vol%" means volume percentage, "mol%" means mole percentage, "ppm" means parts per million, and "ppm wt" and "wppm" are used interchangeably to mean parts per million by weight. All concentrations herein are expressed based on the total amount of the composition in question unless otherwise specified.

[0012] The term "polymer" refers to any two or more of the same or different repeating / mer units or units. The term "homopolymer" refers to a polymer having units that are the same. The term "copolymer" refers to a polymer having two or more units that are different from each other, including terpolymers and the like. The term "terpolymer" refers to a polymer having three units that are different from each other. The term "different" when it refers to units means that the units differ from each other by at least one atom or analogically. Similarly, the definition of polymer as used herein includes homopolymers, copolymers, and the like. By way of example, when a copolymer is said to have a "propylene" content of 10 wt% to 30 wt%, it is understood that the repeating / mer units or simply units in the copolymer are derived from propylene in the polymerization reaction, and the derived units are present at 10 wt% to 30 wt% based on the weight of the copolymer.

[0013] The term "continuous" refers to a system that operates without interruption or cessation. For example, a continuous process for producing a polymer would be one in which reactants are continuously introduced into one or more reactors and the polymer product is continuously withdrawn. The term "solution polymerization" refers to a polymerization process in which the polymer is dissolved in a liquid polymerization medium, such as an inert solvent, monomer(s), or a blend thereof. Solution polymerizations are typically homogeneous. The term "homogeneous polymerization" refers to a polymerization process in which the polymer product is dissolved in the polymerization medium. The system is preferably not turbid, as described in J. Vladimir Oliveira, C. Dariva, and JC Pinto, Ind. Eng. Chem. Res., 29, 2000, 4627. A homogeneous polymerization process is typically one in which at least 90 wt% of the product is dissolved in the reaction medium.

[0014] The term "laminar" flow refers to the flow of a fluid (e.g., gas, liquid) in parallel layers without disruption between the layers. Fluids may exhibit laminar flow near solid boundaries. "Near-laminar" flow refers to the flow of a fluid in parallel layers with minimal disruption between the layers. As used herein, "Mn" refers to the number average molecular weight of the various polymers in the polymeric material, "Mw" refers to the weight average molecular weight of the various polymers in the polymeric material, and "Mz" refers to the z-average molecular weight of the various polymers in the polymeric material. The terms "molecular weight distribution" (MWD) and "polydispersity index" (PDI) are used interchangeably to refer to the ratio of Mw to Mn. Unless otherwise noted, all molecular weights (Mw, Mn, Mz) are reported in g / mole. The nomenclature of elements and their groups used herein follows the Periodic Table used by the International Union of Pure and Applied Chemistry since 1988. An example of a Periodic Table is shown on the inside front cover page of Advanced Inorganic Chemistry, 6th Edition by F. Albert Cotton et al. (John Wiley & Sons, Inc., 1999).

[0015] A detailed description is provided below. Each appended claim defines a separate invention, which is recognized for infringement purposes as including equivalents to the various elements or limitations specified in the claim. Depending on the context, all references to the "invention" may refer only to certain specific embodiments. In other cases, it will be recognized that references to the "invention" refer to one or more, but not necessarily all, of the subject matter recited in the claims. Each of the inventions is described in more detail below, including specific embodiments, variations, and examples, but the invention is not limited to these embodiments, variations, or examples, and these embodiments, variations, or examples are included to enable one of ordinary skill in the art to make and use the invention when the information in this disclosure is used in conjunction with publicly available information and technology.

[0016] Provided herein is a process for the manufacture of olefin copolymers, which may include introducing an olefin monomer, at least one other comonomer, and a single type of catalyst system into a single tubular reactor to produce the olefin comonomer. The term "tubular reactor" refers to a reactor into which a feed is continuously introduced (e.g., via an inlet) and from which a product is continuously removed (e.g., via an outlet), and in which there is typically no stirring. For example, the tubular reactor may be substantially tubular in shape and may include straight pipes or loops to allow for recirculation. The tubular reactor may include one or more plug flow components and / or one or more laminar flow elements. The tubular reactor may include a recirculation pump. Preferably, the tubular reactor may include one or more heat exchangers. The heat exchanger(s) may be a spiral wound heat exchanger (SHE). Surprisingly, it is possible to produce olefin copolymers with a wide comonomer distribution and a wide molecular weight distribution (MWD) along the polymer chain, as determined by gel permeation chromatography (GPC), even in the presence of hydrogen, using only a single tubular reactor with a single type of catalyst system, including a single-site catalyst.As already mentioned, olefin copolymers with these properties cannot usually be produced using only one catalyst system and one tubular reactor.Also, the copolymers cannot usually be produced using a continuous stirred tank reactor (CSTR).Thus, the process disclosed herein is not only simpler than the process used to produce olefin copolymers with these properties, but also more cost-effective.

[0017] The absolute comonomer distribution (CD) slope 25, slope 50, slope 75, and slope 90 of the olefin copolymers produced herein can unexpectedly range from 2.0 to 30.0. This suggests that these copolymers can have broad comonomer distributions. One or two or all of the absolute slopes can be greater than 2. The absolute slopes can increase in ascending order from slope 25 to slope 90, or the absolute slopes can increase in descending order from slope 90 to slope 25, or the absolute slopes can increase in random order. Polymers with broad comonomer distributions have either relatively high molecular weight chains with low comonomer incorporation or relatively low molecular weight chains with high comonomer incorporation. In a preferred embodiment, the absolute CD slope 75 of the olefin copolymers ranges from 2.0 to 20.0. In a preferred embodiment, the absolute CD slope 90 of the olefin copolymers ranges from 2.0 to about 20.0. For all Mz / Mw values ​​in the range of 1.5 to 6.0, the absolute slope average, i.e., (slope 50+slope 75) / 2, (slope 25+slope 50) / 2, and (slope 75+slope 90) / 2, of the olefin copolymer may have a value of up to 15.0, preferably from 0.1 to 12.0, more preferably from 0.1 to 10.0. In a preferred embodiment, the olefin copolymer has an absolute slope average in the range of 1.5 to 12.0 for all Mz / Mw values ​​in the range of 1.8 to 6.0.

[0018] The copolymers produced herein may have MWD (Mw / Mn) in the range of 2.0 to 7.0, suggesting that the MWD of the copolymers may be broad. In a preferred embodiment, the MWD of the olefin copolymers is in the range of 2.0 to about 6.0. The copolymers may have Mz / Mw values ​​in the range of 1.5 to 6.0, preferably 1.8 to 6.0, and more preferably 1.8 to 5.0. The copolymers may also have Mz / Mn values ​​in the range of 3.0 to 40.0, preferably 3.0 to 30.0, and more preferably 3.0 to 25.0. Procedures that can be used to determine the CD slope, molecular weight moment, and molecular weight distribution are described in the Examples below. Advantageously, the polyolefin copolymers produced herein may also exhibit low levels of long chain branching (LCB). In particular, the copolymers may have a first long chain branching index (g'(Mz)) ranging from 0.30 to 1.00, preferably from 0.70 to 0.97. The copolymers may have a second long chain branching index (g'(Mz+1)) ranging from 0.30 to 1.00, preferably from 0.70 to 0.97. A description of the method used to determine LCB can be found in the Examples below. The olefin copolymers produced herein may have densities of 0.850 g / cc to 0.920 g / cc, as measured according to ASTM D792, suggesting that the olefin copolymers may be useful as plastomers, combining the qualities of elastomers and polymers. The olefin copolymers may have a wide range of melt index (MI) values, ranging from 0.1 dg / min to 500.0 dg / min, and melt index ratios (MIR) (MI Ratios) ranging from 20.0 to about 100.0. 21.6 / MI 2.16 ), both measured according to ASTM D1238 (190°C / 2.16 kg).

[0019] Another advantage of the processes disclosed herein is that the weight average molecular weight (Mw), and therefore the MWD, comonomer distribution, and level of long chain branching, can all be controlled for the copolymers produced herein using the following exemplary equation: Mw can be calculated using the following equation: (Mw) 2.2 =-2.1E+011+1.5E+9*Tavg-2.7E+8*H2 / C2+4.1E+10*C2conc+3.4E+011*C8conc-1.8E+9*Tavg*C8conc-1.9E+010*C2conc*C8conc where Tavg is the average reactor inlet and outlet temperatures in °C, H2 / C2 is the molar ratio of hydrogen to ethylene introduced into the reactor, C2conc is the ethylene concentration in wt%, C8conc is the concentration of at least one other comonomer in wt% (e.g., octene concentration), and all mass percentages are based on the total mass of solution introduced into the reactor. The Mw in g / mole can be controlled based on the calculated Mw. The CD slope 90 can be calculated using the following equation: Sqrt(gradient 90)=+0.11-7.6E-003*H2 / C2+0.5*C2conc-0.2*C8conc+0.20*cementconc where H2 / C2 is the molar ratio of hydrogen to ethylene introduced into the reactor, C2conc is the ethylene concentration in wt%, C8conc is the concentration of at least one other comonomer (e.g., octene concentration) in wt%, and Cementconc is the cement concentration in wt%, all mass percentages based on the total mass of solution introduced into the reactor. The comonomer distribution can be controlled based on the calculated CD slope 90.

[0020] The CD slope 75 can be calculated using the following equation: Sqrt(gradient 75) = +2.6-0.011*Tavg-5.7E-003*H2 / C2+0.13*C2conc-0.06*C8conc+0.10*cementconc where Tavg is the average reactor inlet and outlet temperatures in °C, H2 / C2 is the molar ratio of hydrogen to ethylene introduced into the reactor, C2conc is the ethylene concentration in wt%, C8conc is the concentration of at least one other comonomer in wt% (e.g., octene concentration), and Cementconc is the cement concentration in wt%, all mass percentages based on the total mass of solution introduced into the reactor. Comonomer distribution can also be controlled based on the calculated CD slope75. The long chain branching index g'(Mz) can be calculated using the following equation: g'-Mz=+0.89+1.47E-004*H2 / C2+0.02*C2conc-2.8E-003*C8conc-2.8E-005*P RPM where H2 / C2 is the molar ratio of hydrogen to ethylene introduced into the reactor, C2conc is the ethylene concentration in wt%, C8conc is the concentration of at least one other comonomer in wt% (e.g., octene concentration), and P RPM is the pump rate of the reactor, and all mass percentages are based on the total mass of the solution introduced into the reactor. Based on the calculated g'(Mz), the long chain branching index can be controlled.

[0021] Polymerization Process The polymerization process may be a solution polymerization process in which the monomer, comonomer, and catalyst system are contacted in a solution phase in which a polymer is formed. Preferably, the solution polymerization process is a bulk polymerization process. As used herein, "bulk polymerization" refers to a polymerization process in which the monomer and / or comonomer to be polymerized is used as a solvent or diluent, with little or no inert solvent as a liquid or diluent. Sometimes only a small amount of inert solvent is used as a carrier and scavenger for the catalyst. In a preferred embodiment, the monomer and comonomer feed concentration for the polymerization is 60 vol.% or less, preferably 40 vol.% or less, and more preferably 20 vol.% or less, based on the total volume of the feedstream.

[0022] Monomers and Comonomers The olefin monomer may be or include a substituted or unsubstituted C2-C40 olefin, preferably a C2-C20 olefin, more preferably a C2-C12 olefin, such as ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, and isomers thereof. The at least one other olefin comonomer may be or include a substituted or unsubstituted C4-C40 olefin, preferably a C4-C20 olefin. In one or more embodiments, the monomer may be ethylene and the at least one other comonomer may include a C4-C20 olefin. The C4-C20 olefin comonomer may be linear, branched, or cyclic. Suitable C4-C20 cyclic olefins may be strained or unstrained, monocyclic or polycyclic, and may optionally include heteroatoms and / or one or more functional groups. The C2 concentration in the reactor may range from 0.1 to 40.0 wt%, and the comonomer concentration in the reactor may range from 0.1 to 40.0 wt%. Specific examples of the at least one comonomer include butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, norbornene, norbornadiene, dicyclopentadiene, cyclopentene, cycloheptene, cyclooctene, cyclooctadiene, cyclododecene, 7-oxanorbornene, 7-oxanorbornadiene, substituted derivatives thereof, and isomers thereof, preferably hexene, heptene, octene, nonene, decene, dodecene, cyclooctene, 1,5-cyclooctadiene, 1-hydroxy-4-cyclooctene, 1-acetoxy-4-cyclooctene, 5-methylcyclopentene, cyclopentene, dicyclopentadiene, norbornene, norbornadiene, and their respective homologs and derivatives, preferably norbornene, norbornadiene, and dicyclopentadiene.

[0023] In preferred embodiments, one or more dienes (diolefin monomers) are added to the polymerization process. The diene may be present in the polymer produced herein at up to 10 wt%, preferably 0.00001-8.0 wt%, preferably 0.002-8.0 wt%, more preferably 0.003-8.0 wt%, based on the total weight of the composition. In some embodiments, 500 ppm or less, preferably 400 ppm or less, preferably 300 ppm or less of diene is added to the polymerization. In other embodiments, at least 50 ppm, or 100 ppm or more, or 150 ppm or more of diene is added to the polymerization. Suitable diolefin monomers include any hydrocarbon structure, preferably C4-C30, with at least two unsaturated bonds, at least one of which is easily incorporated into the polymer chain during chain growth. More preferred are diolefin monomers selected from α,ω-diene monomers (i.e., divinylic monomers). More preferably, the diolefin monomer is a linear divinylic monomer, most preferably a linear divinylic monomer containing from 4 to 30 carbon atoms. Specific examples of preferred dienes include butadiene, pentadiene, hexadiene, heptadiene, octadiene, nonadiene, decadiene, undecadiene, dodecadiene, tridecadiene, tetradecadiene, pentadecadiene, hexadecadiene, heptadecadiene, octadecadiene, nonadecadiene, icosadiene, heneicosadiene, docosadiene, tricosadiene, tetracosadiene, pentacosadiene, hexadecadiene ... Particularly preferred dienes include 1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene, 1,10-undecadiene, 1,11-dodecadiene, 1,12-tridecadiene, 1,13-tetradecadiene, and low molecular weight (Mw less than 1000 g / mol) polybutadiene. Preferred cyclic dienes include cyclopentadiene, 5-vinyl-2-norbornene, norbornadiene, 5-ethylidene-2-norbornene, divinylbenzene, and dicyclopentadiene or higher ring containing diolefins with or without substitution at various ring positions.

[0024] Catalyst Systems The term "catalyst system" refers to a catalyst precursor / activator pair. When "catalyst system" is used to describe the pair before activation, it refers to the unactivated catalyst (pre-catalyst) along with an activator and, optionally, a co-activator. When "catalyst system" is used to describe the pair after activation, it refers to the activated catalyst and an activator or other charge-balancing component. The transition metal compound may be neutral, as in a pre-catalyst, or may be a charged species with a counterion, as in an activated catalyst system. The term "catalyst system" may also include multiple catalyst precursors and / or multiple activators and, optionally, a co-activator. The catalyst systems used in the polymerization processes described herein may include bridged metallocene compounds having a single substituted carbon or silicon bridging two auxiliary monoanionic ligands of the metallocene metal center, such as substituted or unsubstituted cyclopentadienyl-containing (Cp) ligands and / or substituted and unsubstituted Group 13-16 heteroatom ligands. The bridging substituents may be substituted aryl groups, which include at least one solubilizing hydrocarbylsilyl substituent disposed on at least one of the aryl group bridging substituents. The substituents present on the cyclopentadienyl and / or heteroatom ligands may include C1-C aryl groups as replacements for one or more of the hydrogen groups on the ligand or the hydrogen groups on the fused aromatic rings on the cyclopentadienyl ring. 30It may contain hydrocarbyl, hydrocarbylsilyl, or hydrofluorocarbyl groups. Aromatic rings may be substituents on cyclopentadienyl ligands, including indenyl and fluorenyl derivatives of cyclopentadienyl groups and their hydrogenated counterparts. The aromatic rings typically contain one or more aromatic ring substituents selected from linear, branched, cyclic, aliphatic, aromatic, or complex structural groups (including fused or pendant arrangements). Examples include methyl, isopropyl, n-propyl, n-butyl, isobutyl, tertiary butyl, neopentyl, phenyl, n-hexyl, cyclohexyl, benzyl, and adamantyl. As used herein, the term "hydrocarbon" or "hydrocarbyl" is meant to include compounds or groups that have essentially hydrocarbon character, but that optionally contain up to about 10 mole % of non-carbon heteroatoms, such as boron, silicon, oxygen, nitrogen, sulfur, and phosphorus. Additionally, the term is meant to include hydrofluorocarbyl-substituted groups. "Hydrocarbylsilyl" is exemplified by, but not limited to, dihydrocarbylsilyl and trihydrocarbylsilyl, with preferred hydrocarbyl groups being C-C for the bridging group phenyl. 30 The substituent is hydrocarbyl, hydrocarbylsilyl or hydrofluorocarbyl substituent. For heteroatom-containing catalysts, see International Publication No. WO92 / 00333. Also, the use of heteroatom-containing rings or fused rings (where non-carbon group 13, 14, 15 or 16 atom replaces one ring carbon) is considered to be within the scope of the terms "cyclopentadienyl", "indenyl" and "fluorenyl" herein. For example, see the background and teachings of International Publication Nos. WO98 / 37106 and WO98 / 41530, the contents of which are incorporated herein by reference.

[0025] Particularly suitable cyclopentadienyl-based complexes are the compounds, isomers or mixtures of (para-trimethylsilylphenyl)(para-n-butylphenyl)methylene(fluorenyl)(cyclopentadienyl)hafnium dimethyl, di(para-trimethylsilylphenyl)methylene(2,7-di-tert-butylfluorenyl)(cyclopentadienyl)hafnium dimethyl, di(para-triethylsilylphenyl)methylene(2,7-di-tert-butyl-fluorenyl)(cyclopentadienyl)hafnium dimethyl, (para-triethylsilylphenyl)(para-t-butylphenyl)methylene(2,7-di-tert-butylfluorenyl)(cyclopentadienyl)hafnium dimethyl or dibenzyl, and di(para-triethylsilyl-phenyl)methylene(2,7-dimethylfluorenyl)(cyclopentadienyl)hafnium dimethyl or dibenzyl.

[0026] The bridged metallocene compounds can be activated for polymerization catalysis in any manner sufficient to allow coordination or cationic polymerization. For coordination polymerization, this can be accomplished when one ligand can be abstracted and another ligand can be similarly abstracted for replacement with a ligand that allows the insertion of an unsaturated monomer or allows the insertion of an unsaturated monomer (a labile ligand), such as an alkyl, silyl, or hydride. Traditional activators of coordination polymerization techniques are suitable, such as Lewis acids, such as alumoxane compounds, and ionizing anion precursor compounds that abstract one ligand to ionize the metal center of the bridged metallocene to a cation and provide the balancing non-coordinating anion. The catalyst system may also incorporate other types of single-site catalysts, such as half-metallocenes and post-metallocenes. For a detailed description of suitable catalyst systems, see also International Publication Nos. WO / 2000 / 024793 and WO / 2021 / 162748, the contents of which are each incorporated herein by reference.

[0027] Tubular Reactor System The tubular reactor system may include one or more spiral heat exchangers. For example, as shown in FIG. 1a, stream 1, including monomer, comonomer, and catalyst system, may enter tubular reactor 2 and travel through spiral heat exchanger 3. Stream 4, including copolymer product, unreacted monomer and / or comonomer, and quenched or unquenched catalyst system, may exit reactor 2. Stream 5, including heat exchange medium, may flow through spiral heat exchanger 3. At least one spiral heat exchanger may include a body formed by at least one spiral sheet wound to form a spiral radially disposed around the axis of the spiral heat exchanger. The spiral may form at least one flow path for the flow of the heat exchange medium, and the spiral may be substantially enclosed by a cylindrical shell, as shown in FIG. 2. The cylindrical shell may also include at least one inlet and at least one outlet in fluid communication with at least one flow path for supplying and removing the heat exchange medium.

[0028] The at least one spiral heat exchanger may be oriented such that the monomer, comonomer, catalyst system, and copolymer product flow axially through the flow passages formed between the spirals 6 of the at least one spiral heat exchanger, as shown in FIG. 1b, thereby allowing the feed and polymer product to flow as they move through the at least one spiral heat exchanger. In other words, the monomer, comonomer, catalyst system, and copolymer product may flow through the at least one spiral heat exchanger in a cross-flow direction relative to the spirals of the at least one spiral heat exchanger. As used herein, a "cross-flow" direction refers to a flow that is substantially orthogonal to the spirals of the at least one spiral heat exchanger. Substantially orthogonal may include the monomer, comonomer, catalyst system, and copolymer product flow at an angle of 70° to 110°, preferably 80° to 100°, more preferably 85° to 95°, more preferably 88° to 92°, and most preferably 90°, relative to the spirals of the at least one spiral heat exchanger.

[0029] As shown in FIG. 1b, the at least one spiral heat exchanger can be arranged in a substantially vertical direction such that the monomer, comonomer, catalyst system, and copolymer product flow through the at least one spiral heat exchanger in a substantially vertical direction. The geometrical arrangement of the at least one spiral heat exchanger is not limited to the vertical arrangement, but can be arranged in any direction, so long as the feed and product flow through the at least one spiral heat exchanger in a cross-flow direction relative to the spirals of the at least one spiral heat exchanger. For example, the at least one spiral heat exchanger can be arranged in a substantially horizontal direction such that the monomer, comonomer, catalyst system, and copolymer product flow through the at least one spiral heat exchanger in a substantially horizontal direction, as shown in FIG. 2. Alternatively, the at least one spiral heat exchanger can include a plurality, e.g., at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13, at least 14, at least 15, at least 16, at least 17, at least 18, at least 19, at least 20, at least 21, at least 22, at least 23, at least 24, etc., spiral heat exchangers.

[0030] The at least one spiral heat exchanger used in the process described herein may be any suitable spiral heat exchanger known in the art.Non-limiting examples of suitable spiral heat exchangers include those described in U.S. Patent Nos. 8,622,030; 8,075,845; 8,573,290; 7,640,972; 6,874,571; 6,644,391; 6,585,034; and 4,679,621; U.S. Publication Nos. 2010 / 0170665; 2010 / 0008833; 2002 / 0092646; and 2004 / 0244968, and International Publication No. WO / 2017 / 058385, the contents of each of which are incorporated herein by reference. Additionally or alternatively, the at least one spiral heat exchanger has a diameter of about 66 to about 98 m 2 / m 3 (20 to 30 ft2 / ft3). Advantageously, the spiral heat exchanger may have an open circuit height of 0.15 to 9.1 m (0.5 to 30 ft), preferably 0.3 to 7.6 m (1 to 25 ft), 0.9 to 6.1 m (3 to 20 ft), 1.5 to 4.6 m (5 to 15 ft), or 1.5 to 3 m (5 to 10 ft).

[0031] The heat exchange medium flowing through the spirals of the at least one spiral heat exchanger may be any suitable heat exchange medium known in the art. Particularly useful heat exchange media include media that are stable at the reaction temperature, typically at 200° C. or higher. Examples of heat transfer media include water and other aqueous solutions, oils (e.g., hydrocarbons such as mineral oil, kerosene, hexane, pentane, etc.), and synthetic media, such as those commercially available under the trade name DOWTHERM™ from The Dow Chemical Company (Midland, Michigan), e.g., grades A, G, J, MX, Q, RP, and T. When water is used, it is preferred that the water is under an appropriate amount of pressure so that it does not boil. Preferably, the heat exchange medium flows through the spirals at a temperature below the temperature of the feed stream. Additionally or alternatively, the heat exchange medium may flow through the spirals at a temperature above the precipitation point of the polymer. For example, the heat exchange medium may flow through the spiral at a temperature of 100°C to 150°C, preferably 120°C to 140°C, and more preferably 130°C.

[0032] In various embodiments, the at least one spiral heat exchanger is configured to provide a heat exchanger having a heat capacity of > about 100 Btu / hr-cubic feet-°F (about 1,860 W / cubic meters-°C), > about 150 Btu / hr-cubic feet-°F (about 2,795 W / cubic meters-°C), > about 200 Btu / hr-cubic feet-°F (about 3,725 W / cubic meters-°C), > about 250 Btu / hr-cubic feet-°F (about 4,000 W / cubic meters-°C), > about 300 Btu / hr-cubic feet-°F (about 5,000 W / cubic meters-°C), > about 400 Btu / hr-cubic feet-°F (about 6,000 W / cubic meters-°C), > about 500 Btu / hr-cubic feet-°F (about 7,000 W / cubic meters-°C), > about 600 Btu / hr-cubic feet-°F (about 8,000 W / cubic meters-°C), > about 700 Btu / hr-cubic feet-°F (about 9,000 W / cubic meters-°C), > about 800 Btu / hr-cubic feet-°F (about 10,000 W / cubic meters-°C), > about 900 Btu / hr-cubic feet-°F (about 11,000 W / cubic meters-°C), > about 1000 Btu / hr-cubic feet-°F (about 12,000 W / cubic meters-°C), > about 1500 Btu / hr-cubic feet-°F (about 16,000 W / cubic meters-°C), > about 1600 Btu / hr-cubic feet-°F (about 17,000 W / cubic meters-°C), > about >300 Btu / hour-cubic foot-°F (approx. 5,590 W / cubic meter-°C), >350 Btu / hour-cubic foot-°F (approx. 6,520 W / cubic meter-°C), >400 Btu / hour-cubic foot-°F (approx. 7,450 W / cubic meter-°C), >450 Btu / hour-cubic foot-°F (approx. 8 ,385W / cubic meter-℃), >approx. 500 Btu / hour-cubic foot-°F (approx. 9,315W / cubic meter-℃), >approx. 550 Btu / hour-cubic foot-°F (approx. 10,245W / cubic meter-℃), >approx. 600 Btu / hour-cubic foot-°F (approx. 11,180W / cubic meter-℃), >approx. 650 Btu / hour-cubic foot-°F (approx. 12,110 The at least one spiral heat exchanger can remove heat (e.g., generated during the polymerization reaction) at a rate of > about 700 Btu / hr-ft-°F (about 13,040 W / m-°C), > about 750 Btu / hr-ft-°F (about 13,970 W / m-°C), or > about 800 Btu / hr-ft-°F (about 14,905 W / m-°C). Preferably, the at least one spiral heat exchanger can remove heat at a rate of > about 400 Btu / hr-ft-°F (about 7,450 W / m-°C). Expressly disclosed ranges include any combination of the above recited values, for example, from about 100 to about 800 Btu / hour-cubic feet-°F (about 1,860 to about 14,905 W / cubic meters-°C), from about 200 to about 650 Btu / hour-cubic feet-°F (about 3,725 to about 12,110 W / cubic meters-°C), from about 350 to about 550 Btu / hour-cubic feet-°F (about 6,520 to about 10,245 W / cubic meters-°C).Preferably, the at least one spiral heat exchanger removes heat at a rate of from about 100 to about 800 Btu / hr-cubic feet-°F (about 1,860 to about 14,905 W / cubic meter-°C), more preferably from about 200 to about 700 Btu / hr-cubic feet-°F (about 3,725 to about 13,040 W / cubic meter-°C), and more preferably from about 300 to about 500 Btu / hr-cubic feet-°F (about 5,590 to about 9,315 W / cubic meter-°C).

[0033] Additionally, the use of at least one spiral heat exchanger in the polymerization processes described herein advantageously results in low pressure drop, leading to higher recycle and production rates. For example, the pressure drop across the at least one spiral heat exchanger may be < about 6.9 hPa (0.1 psi), < about 14 hPa (0.2 psi), < about 21 hPa (0.3 psi), < about 28 hPa (0.4 psi), < about 34 hPa (0.5 psi), < about 41 hPa (0.6 psi), < about 48 hPa (0.7 psi), < about 55 hPa (0.8 psi), < about 62 hPa (0.9 psi), < about 69 hPa (1.0 psi), < about 138 hPa (2.0 psi), < about 207 hPa (3.0 psi), < about 300 hPa (4.0 psi), < about 350 hPa (5.0 psi), < about 300 hPa (6.0 psi), < about 350 hPa (7.0 psi), < about 300 hPa (8.0 psi), < about 350 hPa (9.0 psi), < about 300 hPa (10.0 psi), < about 300 hPa (11.0 psi), < about 300 hPa (12.0 psi), < about 300 hPa (13.0 psi), < about 300 hPa (14.0 psi), < about 300 hPa (15.0 psi), < about 300 hPa (16.0 psi), < about 300 hPa (17.0 psi), < about 300 hPa (18.0 psi), < about 300 hPa (19.0 psi), < about 400 hPa (20.0 psi), < about 400 hPa (21.0 psi), < about 400 si), < about 276 hPa (4.0 psi), < about 345 hPa (5.0 psi), < about 414 hPa (6.0 psi), < about 483 hPa (7.0 psi), < about 552 hPa (8.0 psi), < about 621 hPa (9.0 psi), < about 689 hPa (10.0 psi), < about 827 hPa (12.0 psi), < about 965 hPa (14.0 psi), < about 1103 hPa (16.0 psi), < about 1241 hPa (18.0 psi), or < about 1379 hPa (20.0 psi). The pressure drop across the at least one spiral heat exchanger may be < about 689 hPa (10.0 psi), preferably < about 345 hPa (5.0 psi), more preferably < about 69 hPa (1.0 psi). Expressly disclosed ranges include any combination of the above recited values, such as, for example, from about 0.1 psi to about 20.0 psi, from about 0.5 psi to about 16.0 psi, from about 1.0 psi to about 12.0 psi, from about 3.0 psi to about 8.0 psi, etc. Preferably, the pressure drop across at least one spiral heat exchanger is from about 0.1 psi to about 14.0 psi, more preferably from about 0.5 psi to about 10.0 psi, and even more preferably from about 0.8 psi to about 2.0 psi, or from 0.2 psi to 0.8 psi per stage.

[0034] In various embodiments, the monomer, comonomer, catalyst system, and polymer may be maintained as substantially a single liquid phase under polymerization conditions. The flow of liquid through the at least one spiral heat exchanger may be substantially laminar or near laminar. Preferably, the Reynolds number of the liquid flow can be >about 0.1, >about 1.0, >about 10.0, >about 20.0, >about 30.0, >about 40.0, >about 50.0, >about 60.0, >about 70.0, >about 80.0, >about 90.0, >about 100, >about 200, >about 300, >about 400, >about 500, >about 600, >about 700, >about 800, >about 900, >about 1,000, >about 1,100, >about 1,200, >about 1,300, >about 1,400, >about 1,500, >about 1,600, >about 1,700, >about 1,800, >about 1,900, >about 2,000, >about 2,100, or about 2,200. Additionally or alternatively, the Reynolds number of the liquid stream can be < about 40.0, < about 50.0, ≦ about 60.0, ≦ about 70.0, ≦ about 80.0, ≦ about 90.0, ≦ about 100, ≦ about 200, < about 300, ≦ about 400, ≦ about 500, ≦ about 600, ≦ about 700, ≦ about 800, ≦ about 900, ≦ about 1,000, ≦ about 1,100, ≦ about 1,200, ≦ about 1,300, ≦ about 1,400, ≦ about 1,500, ≦ about 1,600, ≦ about 1,700, ≦ about 1,800, ≦ about 1,900, ≦ about 2,000, ≦ about 2,100 or < about 2,200. Explicitly disclosed ranges include any combination of the above recited values, such as about 0.1 to about 2,200, about 1.0 to about 1,400, about 1.0 to about 100, about 50.0 to about 900, etc. Preferably, the Reynolds number of the liquid is about 0.1 to about 2,200, preferably about 1.0 to about 1,000, preferably about 1.0 to about 100, more preferably about 1.0 to about 50. The Reynolds number is calculated using the hydraulic diameter (Dh), which is defined as Dh = 4A / P, where A is the cross-sectional area of ​​the cross section of the flow passage of the spiral heat exchanger, and P is the wetted perimeter. Zero shear viscosity is used to calculate the Reynolds number when using non-Newtonian fluids.

[0035] The polymerization process can be carried out at a temperature of about 50° C. to about 220° C., preferably about 70° C. to about 210° C., preferably about 90° C. to about 200° C., preferably about 100° C. to about 190° C., preferably about 130° C. to about 160° C. The polymerization process can be carried out at a pressure of about 120 to about 1,800 psi (827.371 to 12,410.560 kPa), preferably about 200 to about 1,000 psi (1,378.950 to 6,894.760 kPa), preferably about 300 to about 800 psi (2,068.430 to 5,515.810 kPa). In various embodiments, the residence time in at least one spiral heat exchanger can be up to 24 hours or more, typically from about 1 minute to about 15 hours. The residence time is preferably from about 2 minutes to about 1 hour, from about 3 to about 30 minutes, from about 5 to about 25 minutes, or from about 5 to about 20 minutes. In some embodiments, hydrogen may be present during the polymerization process at a partial pressure of about 0.001 to about 50,000 psig (0.007 to 344.738 kPa), preferably about 0.010 to about 25,000 psig (0.069 to 172.369 kPa), and more preferably about 0.100 to about 10,000 psig (0.689 to 482.633 kPa). Alternatively, the hydrogen concentration in the feed may be 500 wppm or less, preferably 200 wppm or less. In various embodiments, the cement concentration of the resulting polymer can range from about 2 wt% to about 40 wt%, preferably from about 5 wt% to about 30 wt%, and more preferably from about 6 wt% to about 25 wt%. "Cement concentration" is defined herein as the mass of the resulting polymer based on total solvent (e.g., monomer, comonomer, and / or solvent).

[0036] The polymerization process may further comprise the step of recycling at least a portion of the solvent, monomer / comonomer, catalyst system, and polymer in the tubular reactor back through the tubular reactor. The polymer may be produced at a circulation ratio ranging from about 3 to about 50, preferably from about 3 to about 30, and more preferably from about 3 to about 20. The circulation ratio is defined herein as the ratio of the flow rate of the recycle loop just before entering the spiral heat exchanger (single or series) divided by the flow rate of the unused feed to the spiral heat exchanger (single or series). EXAMPLES

[0037] Working Example: The foregoing discussion can be further illustrated with reference to the following non-limiting examples. Seven samples (Examples 1-3) of ethylene (C2) and octene (C8) copolymers were prepared using a tubular reactor ("TR") and a single metallocene-based catalyst system as follows: Catalyst activator (dimethylanilinium tetrakis(pentafluorophenyl)borate), hydrogen (H2), and ethylene (C2) monomer were added to the reactor. Hafnium-based metallocene (MCN) catalyst (as disclosed in paragraph

[0029] ), octene (C8) comonomer, and hexene (C6) were then added to the reactor to initiate the slurry phase polymerization. The amounts of C2, C8, C6, and H2 fed to the reactor were kept constant throughout the polymerization process. The process conditions utilized for Ex. 1-7 are shown in Table 1 below. Commercially available C2 / C8 copolymers (Comparative Examples 1 and 2) from ExxonMobil produced using an MCN catalyst and a CSTR reactor were obtained for comparative purposes. The following C2 / C8 copolymers were also obtained for comparative purposes: Engage™ 8150, Engage™ 11547, and Affinity™ PL 1880, commercially available from Dow Chemical Co. (Comparative Examples 3, 4, and 6, respectively); and Queo™ 06201, commercially available from Borealis AG (Comparative Example 5).

[0038] [Table 1]

[0039] The C8 content, molecular moment, density, and LCB index, MI, MIR, and Solubility Distribution Breadth Index (SDBI) values ​​of samples Ex.1-7 and C.Ex.1-6 are presented in Tables 2-3 below. The densities of Ex.1-3 ranged from 0.882 to 0.886 g / cc, and the MI values ​​of Ex.1-3 ranged from 2.4 to 15.8 dg / min. The MWD (Mw / Mn) of samples Ex.2-3 was greater than that of samples C.Ex.1 and Ex.1 even though they had similar densities. The densities of Ex.4-7 were greater than that of Ex.1-3 which ranged from 0.892 to 0.895 g / cc. As shown in Figure 2, the variation in MWD for samples Ex.4-7 was greater than that of samples Ex.1-3 which ranged from 0.892 to 0.895 g / cc. 21.6 / MI 2.16 The difference in branching index (g'(Mz)) was very evident when the MWD (molecular weight distribution) changed progressively from 26 to 53. The inventive sample of Ex.7 surprisingly showed a broader MWD (2.6) and a smaller LCB index (g'(Mz)) than the samples of Ex.4-6 and C.Ex.2. The branching index g'(Mz) was g' from GPC-4D estimated by z-average (3rd moment) molecular weight average. This calculation was done by curve fitting g' to the molecular weight data with an nth degree polynomial using MATLAB® program. The value of n was typically between 3 and 4. The Mz values ​​obtained from the GPC-IR measurements were inserted into the curve fit to calculate g' related to that molecular weight.

[0040] Figures 3a and 3b show graphs of molecular weight distribution and comonomer distribution for samples Ex.1-3 and C.Ex.1. In Figure 3b, the comonomer distribution is represented as slopes 25, 50, 75, and 90 calculated from the slopes of the comonomer distribution curves estimated at 25%, 50%, 75%, and 90% of the molecular weight distribution, respectively. These slopes were determined by first curve fitting the comonomer content versus molecular weight change to an nth degree polynomial using the MATLAB® program. The value of n was typically between 2 and 4. The derivatives of the curves were obtained at various molecular weight points, which were 25%, 50%, 75%, and 90% of the molecular weight range, respectively. For example, to determine the 25% point on the x-axis, the difference between the minimum molecular weight (mwmin) and the maximum molecular weight (mwmax) was first established for a particular data set. The x-value of slope 25 was calculated as mwmin+0.25*(mwmax-mwmin). The absolute value of the derivative was determined at that point to obtain the slope 25. Slope values ​​in the range of 0-2 were considered to correspond to a homogeneous comonomer distribution, and slopes >2 were considered to correspond to a heterogeneous comonomer distribution. The slope 25, slope 50, slope 75, slope 90, and the average of slopes 50 and 75 for samples Ex.1-7 and C.Ex.1-6 are shown in Tables 2-3 below. As shown in Figure 3b, the inventive sample Ex.3 unexpectedly exhibited a significant increase in slope (>2). This suggests a broad comonomer distribution with higher molecular weight chains having less comonomer content and lower molecular weight chains having more comonomer content. Also, as shown in Tables 2-3, the inventive samples Ex.3 and Ex.7 had much larger average slopes than the samples C.Ex.1-6, Ex.1-2, and Ex.4-6. Furthermore, as shown in Table 2, the change in composition distribution for samples Ex.4-7 was very obvious when the MIR was varied progressively from 26 to 53.

[0041] [Table 2]

[0042] [Table 3]

[0043] Samples Ex.1-3 and C.Ex.1 were analyzed by temperature rising elution fractionation (TREF) technique. Figure 4 shows a graph of the TREF distribution profile for each of these samples. Figure 4 reinforces the broad comonomer distribution profile of the GPC for the inventive sample of Ex.3. The gradual increase in slope and corresponding broadening of composition is particularly noteworthy for samples Ex.1, Ex.2, and Ex.3 compared to the sample of C.Ex.1. This change in composition is primarily due to variations in cement concentration, conversion, and temperature, which affect both the MWD and the composition distribution. The slope of the GPC-4D comonomer profile and the composition distribution estimated from the TREF distribution profile for samples Ex.4-7 and C.Ex.2 are displayed in Figures 5a and 5b, respectively. The inventive sample Ex.7 showed the largest increase in slope at 50, 75, and 90, indicating a broad distribution of comonomer along the polymer chain. The TREF profiles reinforce the gradual increase in slope and corresponding broadening of the composition distribution for samples Ex.4-7 and C.Ex.2. Figure 6 shows the van Gurp-Palment plots for samples Ex.4-7 and C.Ex.2. The above change in branching content is also supported by Figure 6 which shows that for samples Ex.4-7, the phase angle (δ) decreases at constant modulus (G*) while the MIR increases from 26 to 53. Increasing branching levels results in a decrease in the phase angle.

[0044] Based on the data collected for Ex. 1-7, the following equation was determined correlating the weight average molecular weight with the C2 concentration and H2 / C2 molar ratio in the reactor: (Mw) 2.2 =-2.1E+011+1.5E+9*Tavg-2.7E+8*H2 / C2+4.1E+10*C2conc+3.4E+011*C8conc-1.8E+9*Tavg*C8conc-1.9E+010*C2conc*C8conc where Tavg is the average reactor inlet and outlet temperatures in °C, H2 / C2 is the molar ratio of hydrogen to ethylene introduced into the reactor, C2conc is the ethylene concentration in wt%, C8conc is the 1-octene concentration in wt%, and all mass percentages are based on the total mass of solution introduced into the reactor. Adjusted Regression Model Fit R 2 was 0.92. As used herein, R 2 is a measure of the amount of variation about the mean explained by the model. Adjusted R2 is a predictor of model accuracy. A value of 1 means the model perfectly predicts the data, while 0 or negative values ​​indicate a model with no predictive value. Based on the correlation, the relationship between predicted Mw to observed Mw is shown in Figure 7.

[0045] The composition distribution estimated from the slope of the comonomer distribution curve was correlated with the following process parameters: average reactor temperature, H2 / C2 molar ratio, C8 concentration in the reactor, and cement concentration to determine the following equation: Sqrt(gradient 90) = +0.11-7.6E-003*H2 / C2+0.5*C2conc-0.2*C8conc+0.20*cementconc(adjusted R 2 = 0.77); and Sqrt(gradient 75) = +2.6-0.011*Tavg-5.7E-003*H2 / C2+0.13*C2conc-0.06*C8conc+0.10*Cementconc(adjusted R 2 =0.86) where Tavg is the average reactor inlet and outlet temperatures in °C, H2 / C2 is the molar ratio of hydrogen to ethylene introduced into the reactor, C2conc is the ethylene concentration in wt%, C8conc is the 1-octene concentration in wt%, Cementconc is the cement concentration in wt%, and all mass percentages are based on the total mass of solution introduced into the reactor. Figures 8a and 8b show the relationship between the observed slopes of 90 and 75 versus the predicted slopes of 90 and 70 based on these correlations.

[0046] The branching index, measured using g'(Mz), was also correlated with the C2 and C8 concentrations in the reactor based on the following equation: g'-Mz=+0.89+1.47E-004*H2 / C2+0.02*C2conc-2.8E-003*C8conc-2.8E-005*P RPM (Adjustment R 2 =0.85) where H2 / C2 is the molar ratio of hydrogen and ethylene introduced into the reactor, C2conc is the ethylene concentration in wt%, C8conc is the 1-octene concentration in wt%, and P RPM is the pump rate in the reactor, and all mass percentages are based on the total mass of solution introduced into the reactor. Figure 9 shows the relationship between predicted g'(Mz) and observed g'(Mz) as a function of ethylene concentration based on this correlation. Seven samples (Examples 8-14) of copolymers of C2 and C4 (instead of C8) were made similarly to Ex. 1-7. The process conditions for Ex. 8-9 and Ex. 11-14 are shown in Table 4 below. Samples of commercially available C2 / C4 copolymers from ExxonMobil produced using a gas phase reactor and Ziegler-Natta (ZN) catalyst (Comparative Examples 1 and 2); (Comparative Examples 7 and 8) were obtained for comparison purposes.

[0047] [Table 4]

[0048] The C4 content, molecular moments, density, and LCB index, MI, MIR, and SDBI values ​​of samples Ex.8-14 and C.Ex.7-8 are presented in Table 5 below. The inventive samples Ex.8-9 and Ex.13-14 unexpectedly exhibited relatively broad MWDs ranging from 3.5 to 4.9, which were higher than or comparable to the MWDs of samples C.Ex.7-8. Surprisingly, the inventive samples Ex.8 and Ex.10-14 had broader comonomer distributions than samples C.Ex.7-8, as indicated by the average slope values ​​ranging from 2.1 to 5.7.

[0049] [Table 5]

[0050] FIG. 10 shows graphs of the molecular weight distribution curves and comonomer distribution curves of samples Ex.8-9 and C.Ex.8. As shown by the curve of the inventive sample of Ex.8, reactor control was utilized to produce a broader MWD and a broader comonomer distribution, represented by a negative slope. In contrast, sample Ex.9 showed a more uniform comonomer distribution, represented by only a slight slope. FIG. 11 shows a plot of the average slope 50 and slope 75 versus Mz / Mw values ​​for samples Ex.1-14 and C.Ex.1-8. The absolute slope average, i.e., (Slope 50+Slope 75) / 2, was in the range of 0.1-12.0 for all Mz / Mw values ​​in the range of 1.5-6.0. Surprisingly, as represented by the large rectangle shown in FIG. 11, samples Ex.3, 7, 8, 10, 12, 13 and 14 showed better absolute slope averages and Mz / Mw than samples C.Ex.1-8 and all other examples, which fall within the smaller rectangles in FIG. 11. These preferred samples Ex.3, 7, 8, 10, 12, 13 and 14 had absolute slope averages of about 1.5-12.0 and Mz / Mw values ​​of about 1.8 to about 6.0.

[0051] Test procedure In all the above examples, density was measured according to ASTM D792 and the MI and MIR values ​​(MI 21.6 / MI 2.16 ) was measured according to ASTM D1238 (190°C / 2.16 kg). Molecular weight distribution and moments (Mw, Mn, Mz, Mw / Mn, Mz / Mn, etc.), comonomer content (C8), and long chain branching index (g') were determined using high temperature gel permeation chromatography (Polymer Char GPC-IR) equipped with a multiple channel band filter based on infrared detector IR5, an 18-angle light scattering detector, and a viscometer. Three Agilent Plgel 10μm Mixed-B LS columns were used to effect polymer separation. Detailed analytical principles and methods for molecular weight determination are described in paragraphs

[0044] to

[0051] of International Publication No. WO / 2019 / 246069A1, the contents of which are incorporated herein by reference (note that the equation for c referred to in paragraph

[0044] for the concentration I of each point in the chromatogram is c=βI, where β is the mass constant and I is the baseline subtracted IR5 broadband signal intensity (I)). Unless specifically stated otherwise, all molecular weight moments used or mentioned in this disclosure are determined according to conventional molecular weight (IR molecular weight) determination methods (e.g., as referenced in paragraphs

[0044] to

[0045] of the just-mentioned publication), noting that in the equation in paragraph

[0044] , a=0.695 and K=0.000579 (1-0.75Wt) are used, where Wt is the mass fraction of hexane comonomer, and further noting that the comonomer composition is determined by the ratio of the IR5 detector intensities corresponding to the CH2 and CH3 channels calibrated with a series of PE and PP homopolymer / copolymer standards whose nominal values ​​have been previously determined by NMR or FTIR (to give methyls per 1000 total carbons (CH3 / 1000TC) as described in paragraph

[0045] of the just-mentioned International Publication). The TREF procedure was performed as described in Wild, et al., J. Poly. Sci., Poly. Phys. Ed., Vol. 20, pg. 441 (1982) and U.S. Pat. No. 5,008,204, the contents of which are incorporated herein by reference. The SDBI measures the width of the solubility distribution curve for a given polymer. The procedure used herein to calculate the SDBI is described in International Publication No. WO 93 / 03093 (pp. 16-18), the contents of which are incorporated herein by reference.

[0052] LIST OF EMBODIMENTS The present disclosure may further include any one or more of the following non-limiting embodiments. 1. A process for producing an olefin copolymer comprising the steps of introducing an olefin monomer, at least one other olefin comonomer, and a single type of catalyst system into a tubular reactor to produce an olefin copolymer having: a) an absolute comonomer distribution (CD) gradient 90 of about 2.0 to about 30.0, an absolute CD gradient 75 of about 2.0 to about 30.0, an absolute CD gradient 50 of about 2.0 to about 30.0, or an absolute CD gradient 25 of about 2.0 to about 30.0; b) a first long chain branching index (g'(Mz)) of about 0.30 to about 1.0; and c) a second long chain branching index (g'(Mz+1)) of about 0.30 to about 1.0. 2.M Z / M W 2. The process of embodiment 1, wherein the absolute average of CDslope50 and CDslope75, the absolute average of CDslope25 and CDslope50, or the absolute average of CDslope75 and CDslope90 is from about 1.5 to about 12.0 when is about 1.8 to 6.0. 3. The process of embodiment 1 or 2, wherein the tubular reactor comprises a recirculation pump. 4. The process of any one of embodiments 1-2, wherein the tubular reactor comprises a spiral heat exchanger.

[0053] 5. The process of any one of embodiments 1-4, wherein the catalyst system comprises a metallocene catalyst comprising a Group 4 organometallic compound with two ancillary monoanionic ligands, each ligand being independently substituted or unsubstituted, and the ligands being linked by a covalent bridge comprising a single substituted Group 14 atom, the substitutions on the Group 14 atom comprising aryl groups, at least one of which comprises at least one hydrocarbylsilyl substituent. 6. The hydrocarbylsilyl substituent is of the formula R n "SiR' 3-n wherein each R' is independently a C-C 20 Hydrocarbyl, hydrocarbylsilyl, hydrofluorocarbyl substituents, R" is a C1-C bond between Si and the aryl group. 10 6. The process of embodiment 5, wherein n is a linking group and n=0 or 1. 7. The process of any of embodiments 1-6, wherein the olefin monomer and at least one other olefin comonomer are copolymerized using a continuous solution polymerization process.

[0054] 8. The process of any of the preceding embodiments, further comprising introducing hydrogen into the reactor, wherein the olefin monomer is ethylene and the at least one other olefin comonomer comprises at least one C4-C20 olefin. 9. The mass average molecular weight (Mw) of the olefin copolymer is calculated using the following equation: 2.2 =-2.1E+011+1.5E+9*Tavg-2.7E+8*H2 / C2+4.1E+10*C2conc+3.4E+011*C8conc-1.8E+9*Tavg*C8conc-1.9E+010*C2conc*C8conc(In the formula, T avg 9. The process of embodiment 8, further comprising the steps of calculating Mw according to: Mw = M(H2 / C2) / H2+ ... 10. CD slope 90 is calculated using the following equation: Sqrt(slope 90) = +0.11-7.6E-003*H2 / C2+0.5*C2conc-0.2*C8conc+0.20*cementconc (where T avg9. The process of embodiment 8, further comprising calculating CD slope 90 using: CD slope 90 = C / C2 (where C is the average reactor temperature, H2 / C2 is the molar ratio of hydrogen to ethylene introduced into the reactor, C2 is the ethylene concentration in wt%, C8 is the at least one other comonomer concentration in wt%, and Cement is the cement concentration in wt%, all mass percentages based on the total mass of solution introduced into the reactor) and controlling the comonomer distribution based on the calculated CD slope 90. 11. CD slope 75 is calculated using the following equation: Sqrt(Slope 75) = +2.6-0.011*Tavg-5.7E-003*H2 / C2+0.13*C2conc-0.06*C8conc+0.10*CementConc (where T avg 9. The process of embodiment 8, further comprising calculating CD slope 75 using: C2conc = C8conc (where C2conc is the average reactor temperature, H2 / C2 is the molar ratio of hydrogen to ethylene introduced into the reactor, C2conc is the ethylene concentration in wt%, C8conc is the at least one other comonomer concentration in wt%, and Cementconc is the cement concentration in wt%, all mass percentages based on the total mass of solution introduced into the reactor) and controlling the comonomer distribution based on the calculated CD slope 75. 12. The first long chain branching index is calculated using the following equation: g'-Mz=+0.89+1.47E-004*H2 / C2+0.02*C2conc-2.8E-003*C8conc-2.8E-005*P RPM (where H2 / C2 is the molar ratio of hydrogen to ethylene introduced into the reactor, C2conc is the ethylene concentration in wt%, C8conc is the at least one other comonomer concentration in wt%, and P RPM 9. The process of embodiment 8, further comprising the steps of: calculating the first long chain branching index based on the calculated first long chain branching index using (wherein m is the pump speed in the reactor, and all mass percentages are based on the total mass of the solution introduced into the reactor); and controlling the first long chain branching index based on the calculated first long chain branching index.

[0055] 13. The process of embodiment 3, wherein the olefin comonomer is produced at a cement concentration of about 2 wt.% to about 40 wt.% and a recycle rate of about 3 to about 50. 14. The process of any one of the preceding embodiments, wherein the olefin copolymer has an MWD of from about 2.0 to about 7.0. 15. The process of any of the preceding embodiments, wherein the olefin copolymer has a melt index, measured according to ASTM D1238 (190° C. / 2.16 kg), of from about 0.1 dg / min to about 500.0 dg / min. 16. The olefin copolymer has a melt index ratio (MI) of about 20.0 to about 100.0, as measured in accordance with ASTM D1238. 21.6 / MI 2.16 16. The process of any one of embodiments 1 to 15, wherein 17. The process of any of the preceding embodiments, wherein the olefin copolymer has a density, as measured according to ASTM D792, of about 0.850 g / cc to about 0.920 g / cc. 18. The process of any one of the preceding embodiments, wherein the first long chain branching index is from about 0.70 to about 0.97 and the second long chain branching index is from about 0.70 to about 0.97.

[0056] Certain embodiments and features have been described with a set of upper numerical limits and a set of lower numerical limits. It should be understood that ranges including any combination of two values ​​are contemplated, for example, any combination of a lower limit with any upper limit, any combination of two lower limits, and / or any combination of two upper limits, unless otherwise indicated. Certain lower limits, upper limits and ranges appear in one or more claims below. All numerical values ​​are "about" or "approximately" designations and take into account experimental error and variations that would be expected by one of ordinary skill in the art. Various terms have been defined above. Unless a term used in the claims is defined above, it should be given the broadest definition that one skilled in the art would give that term as reflected in at least one publication or issued patent. Furthermore, all patents, test procedures, and other documents cited in this application are incorporated by reference in their entirety to the extent that their disclosures are not inconsistent with this application, and for all authorities to which such incorporation is permitted. While the forgoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, the scope of which is determined by the claims that follow.

Claims

1. 1. A process for producing an olefin copolymer comprising the steps of: introducing an olefin monomer, at least one other olefin comonomer, and a single type of catalyst system into a tubular reactor to produce an olefin copolymer having: a) an absolute comonomer distribution (CD) gradient 90 of about 2.0 to about 30.0; an absolute CD gradient 75 of about 2.0 to about 30.0; an absolute CD gradient 50 of about 2.0 to about 30.0; or an absolute CD gradient 25 of about 2.0 to about 30.0; b) a first long chain branching index (g'(Mz)) of about 0.30 to about 1.0; and c) a second long chain branching index (g'(Mz+1)) of about 0.30 to about 1.

0.

2. M Z / M W 2. The process of claim 1, wherein the absolute average of CD-slope 50 and CD-slope 75, the absolute average of CD-slope 25 and CD-slope 50, or the absolute average of CD-slope 75 and CD-slope 90 is from about 1.5 to about 12.0 when is about 1.8 to 6.

0.

3. 3. The process of claim 1 or 2, wherein the pipe reactor comprises a recirculation pump.

4. 3. The process of claim 1, wherein the tubular reactor comprises a spiral heat exchanger.

5. 5. The process of any one of claims 1 to 4, wherein the catalyst system comprises a metallocene catalyst comprising a Group 4 organometallic compound with two ancillary monoanionic ligands, each of which is independently substituted or unsubstituted, and the ligands are linked by a covalent bridge that comprises a single substituted Group 14 atom, the substitutions on the Group 14 atom comprising aryl groups, at least one of which contains at least one hydrocarbylsilyl substituent.

6. The hydrocarbylsilyl substituent is of the formula R n "SiR' 3-n wherein each R' is independently C 1 -C 20 Hydrocarbyl, hydrocarbylsilyl, hydrofluorocarbyl substituents, R" is the C between Si and the aryl group. 1 -C 10 6. The process of claim 5, wherein n is a linking group and n=0 or 1.

7. The process of any one of claims 1 to 6, wherein the olefin monomer and the at least one other olefin comonomer are copolymerized using a continuous solution polymerization process.

8. 8. The process of any one of claims 1 to 7, further comprising the step of introducing hydrogen into the reactor, wherein the olefin monomer is ethylene and the at least one other olefin comonomer comprises at least one C4-C20 olefin.

9. The weight average molecular weight (Mw) of the olefin copolymer is calculated using the following equation: 2.2 =-2.1E+011+1.5E+9*Tavg-2.7E+8*H2 / C2+4.1E+10*C2conc+3.4E+011*C8conc-1.8E+9*Tavg*C8conc-1.9E+010*C2conc*C8conc (in the formula, T avg 9. The process of claim 8, further comprising the steps of calculating Mw according to: Mw = M(H2 / C2) / H2+ ...

10. The CD slope 90 is calculated by the following equation: Sqrt(Slope 90)=+0.11-7.6E-003*H2 / C2+0.5*C2conc-0.2*C8conc+0.20*Cementconc, where T avg 9. The process of claim 8, further comprising the steps of: calculating CD Slope 90 using: C2conc = C8conc (where C2conc is the average reactor temperature, H2 / C2 is the molar ratio of hydrogen to ethylene introduced into the reactor, C2conc is the ethylene concentration in wt%, C8conc is the at least one other comonomer concentration in wt%, and Cementconc is the cement concentration in wt%, all mass percentages based on the total mass of solution introduced into the reactor; and controlling the comonomer distribution based on the calculated CD Slope 90.

11. The CD slope 75 is calculated by the following equation: Sqrt(Slope 75)=+2.6−0.011*Tavg−5.7E−003*H2 / C2+0.13*C2conc−0.06*C8conc+0.10*CementConc, where T avg 9. The process of claim 8, further comprising the steps of calculating CD slope 75 using: C2conc = C8conc (where C2conc is the average reactor temperature, H2 / C2 is the molar ratio of hydrogen to ethylene introduced into the reactor, C2conc is the ethylene concentration in wt%, C8conc is the at least one other comonomer concentration in wt%, and Cementconc is the cement concentration in wt%, all mass percentages based on the total mass of solution introduced into the reactor) and controlling the comonomer distribution based on the calculated CD slope 75.

12. The first long chain branching index was calculated using the following equation: g'-Mz = +0.89 + 1.47E-004 * H2 / C2 + 0.02 * C2conc - 2.8E-003 * C8conc - 2.8E-005 * P RPM (where H2 / C2 is the molar ratio of hydrogen to ethylene introduced into the reactor, C2conc is the ethylene concentration in wt%, C8conc is the at least one other comonomer concentration in wt%, and P RPM 9. The process of claim 8, further comprising the steps of: calculating a first long chain branching index based on the calculated first long chain branching index using (wherein m is the pump speed in the reactor, and all mass percentages are based on the total mass of solution introduced into the reactor); and controlling the first long chain branching index based on the calculated first long chain branching index.

13. 4. The process of claim 3, wherein the olefin comonomer is produced at a cement concentration of about 2 wt% to about 40 wt% and a recycle rate of about 3 to about 50.

14. The process of any one of claims 1 to 13, wherein the olefin copolymer has an MWD of about 2.0 to about 7.

0.

15. 15. The process of any one of claims 1 to 14, wherein the olefin copolymer has a melt index, measured according to ASTM D1238 (190°C / 2.16 kg), of about 0.1 dg / min to about 500.0 dg / min.

16. The olefin copolymer has a melt index ratio (MI) of about 20.0 to about 100.0, as measured in accordance with ASTM D1238. 21.6 / MI 2.16 16. The process according to any one of claims 1 to 15, comprising:

17. The process of any one of claims 1 to 16, wherein the olefin copolymer has a density of about 0.850 g / cc to about 0.920 g / cc, as measured according to ASTM D792.

18. 18. The process of any one of claims 1 to 17, wherein the first long chain branching index is from about 0.70 to about 0.97 and the second long chain branching index is from about 0.70 to about 0.97.

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