Enhanced polymer devolatilization via controlled foaming

Abstract

Systems and methods for devolatilizing low viscosity polymers. The method comprises providing a reaction mixture comprising a polymer and one or more volatiles, wherein the one or more volatiles comprise one or more unreacted monomers and at least one hydrocarbon solvent; separating the reaction mixture into a polymer-rich phase and a polymer-lean phase in a first separator; separating the polymer-rich phase into a vapour hydrocarbon phase and a concentrated polymer phase in a second separator; removing at least a portion of the volatiles from the concentrated polymer phase within a third separator to provide a devolatilized polymer; and providing a residence time of about 0.2 seconds to 10 seconds within a separator conduit located between the second separator and the third separator.

Description

Inventors: Hamidreza Khakdaman, Andrew Takacs, Michael K. Lyon, Keishla R. Rivera Dones, Rong Ma, Vetkav R. Eswaran, Giriprasath Gururajan Cross - Reference to Related Applications

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 476,390, filed on December 21, 2022, the entire content of which is incorporated herein by reference. Technical Field

[0002] Systems and methods for devolatilization of polymer resins are provided. More specifically, systems and methods for devolatilizing polyalpha - olefins prepared in solution are provided herein. Background Art

[0003] Solution polymerization is one of the many methods by which polymerization can be carried out on an industrial scale. In a solution polymerization process, monomers react in the presence of a catalyst and a solvent (usually a solvent that does not react with the catalyst or the monomers). The monomers and polymers produced by the polymerization reaction are dissolved in the solvent in the reactor. The heat released by the reaction is absorbed by the solvent and removed by various methods, including but not limited to, chilled feed, reflux cooling, cooling jackets, and heat exchangers. The effluent leaving the reactor is a mixture of polymer, solvent, and unreacted monomers. The polymer is separated from the rest of the effluent (i.e., the solvent and unreacted monomers). Then, the polymer is pelletized to form small pellets, which are dried and bagged. Continuous stirred - tank reactors (CSTRs) and non - adiabatic loop reactors are examples of reactors that can be used in solution polymerization processes.

[0004] The polymer product is separated from the solvent and unreacted monomers in a polymer devolatilization unit (Devol unit), which is a multi - stage process with various process conditions. As the polymer solution passes through the different stages of the Devol unit, the polymer concentration increases and the solvent and monomer concentrations decrease. The maximum amount of devolatilization at each stage is governed (i.e., limited) by the equilibrium conditions at a specific temperature and pressure. The goal is to produce a polymer product with a minimum amount of volatile organic compounds (VOCs) at the parts - per - million level.

[0005] In each stage of the Devol unit, sufficient heat of vaporization, a maximum interface between the liquid and vapor, and time are required at specific temperatures and pressures. Generally, in the initial stage of the Devol unit, a large amount of solvent and monomers are separated from the polymer. The amount of solvent separated in each stage is determined by the operating temperature and pressure of each stage. Higher temperatures and lower pressures result in higher devolatilization rates and thus lower solvent concentrations in the polymer product.

[0006] In the final stage of the Devol unit where the solvent concentration in the polymer solution is the lowest, the devolatilization rate is the lowest. This is because the separation process is limited by the rate of solvent mass transfer through the polymer, which is a very slow phenomenon. To increase the mass transfer rate, it is necessary to increase the interface between the solvent and the polymer. One way to increase the interface between the solvent and the polymer is by using a distributor that spreads the polymer solution in a vessel at low pressure. However, such distributors are limited in practicality and cannot provide a sufficiently large surface-to-volume ratio in an economical way. In other words, to increase the surface area-to-volume ratio, the size of the vessel and the distributor becomes very large, and the distributor holes need to be very small, which is limited because the pressure drop across the holes becomes a problem.

[0007] Another way to increase the solvent-polymer interface is to generate bubbles or foams in the polymer solution. The liquid films forming the bubbles and foams will significantly increase the surface-to-volume ratio. Generating bubbles and foams in a polymer solution containing high molecular weight polymers is likely to occur in the typical process operating window of a conventional Devol process (e.g., T = 140 - 210 °C, P = 10 - 50 Torr). However, low molecular weight (low viscosity) polymers do not easily form foams due to their low melt strength.

[0008] Therefore, there is still a need for new systems and methods for devolatilizing low molecular weight (low viscosity) polymers with low melt strength. SUMMARY OF THE INVENTION OVERVIEW OF THE INVENTION

[0009] Systems and methods for devolatilizing low viscosity polymers with low melt strength are provided. In one embodiment, the method includes providing a reaction mixture comprising a polymer and one or more volatiles, wherein the one or more volatiles comprise one or more unreacted monomers and at least one hydrocarbon solvent; separating the reaction mixture into a polymer-rich phase and a polymer-lean phase in a first separator; separating the polymer-rich phase into a vapor hydrocarbon phase and a concentrated polymer phase in a second separator; removing at least a portion of the volatiles from the concentrated polymer phase in a third separator to provide a devolatilized polymer; and providing a residence time of about 0.2 seconds to 10 seconds in a separator conduit located between the second separator and the third separator.

[0010] In another embodiment, the method includes providing a reaction mixture comprising a polymer having a Brookfield viscosity of less than 40,000 cP and a weight average molecular weight (Mw) of less than 62,000 g / mol as determined by GPC and one or more volatiles, wherein the one or more volatiles include one or more unreacted monomers and at least one hydrocarbon solvent; separating the reaction mixture in a first separator into a polymer-rich phase and a polymer-lean phase; separating the polymer-rich phase in a second separator into a vapor hydrocarbon phase and a concentrated polymer phase; removing at least a portion of the volatiles from the concentrated polymer phase in a third separator to provide a devolatilized polymer; and providing a residence time of from about 0.2 seconds to 10 seconds in a separator conduit located between the second separator and the third separator.

[0011] In another embodiment, the method includes providing a reaction mixture comprising a polymer having a Brookfield viscosity of less than 40,000 cP, a weight average molecular weight (Mw) of less than 62,000 g / mol as determined by GPC, and a melt flow rate (MFR) of 500 - 40,000 g / 10 min (ASTM D1238) and one or more volatiles, the one or more volatiles including one or more unreacted monomers and at least one hydrocarbon solvent; separating the reaction mixture in a first separator into a polymer-rich phase and a polymer-lean phase; separating the polymer-rich phase in a second separator into a vapor hydrocarbon phase and a concentrated polymer phase; removing at least a portion of the volatiles from the concentrated polymer phase in a third separator to provide a devolatilized polymer; and providing a residence time of from about 0.2 seconds to 10 seconds in a separator conduit located between the second separator and the third separator under the third separator conditions.

[0012] In one embodiment, the system includes a first separator that separates a reaction mixture comprising a polymer and one or more volatiles into a polymer-rich phase and a polymer-lean phase, wherein the one or more volatiles include one or more unreacted monomers and at least one hydrocarbon solvent, a second separator that separates the polymer-rich phase into a vapor hydrocarbon phase and a concentrated polymer phase; a third separator that removes at least a portion of the volatiles from the concentrated polymer phase; and a separator conduit located between the second separator and the third separator, the separator conduit configured to provide a residence time of from about 0.2 seconds to 10 seconds therein.

[0013] These and other features and attributes of the present disclosure, as well as its advantageous applications and / or uses, will be apparent from the following detailed description. Brief Description of the Drawings

[0014] To assist a person of ordinary skill in the relevant art in making and using the subject matter of the present invention, reference is made to the accompanying drawings, in which:

[0015] Figure 1 An illustrative process flow diagram of a devolatilization unit according to one or more embodiments provided herein is depicted.

[0016] Figure 2 Depicts an enlarged schematic view of an exemplary vacuum flash drum that can be used as the Figure 1 third stage flash drum depicted in.

[0017] Figure 3 Depicts an enlarged schematic view of a polymer solution feed assembly 300 for entering the flash drum 130 depicted in. Figure 2 Depicts an enlarged schematic view of an alternative polymer solution feed section 400 for entering the flash drum 130 depicted in.

[0018] Figure 4 Depicts an enlarged schematic view of an alternative polymer solution feed section 400 for entering the flash drum 130 depicted in. Figure 2 Depicts an enlarged schematic view of an alternative polymer solution feed section 400 for entering the flash drum 130 depicted in.

[0019] Figure 5 Depicts a schematic view of a vacuum flash drum 130 according to one or more embodiments provided herein, Figure 2 which can be configured to utilize multiple feed assemblies 300 and / or 400.

[0020] Figure 6 Depicts a plot of VOC HSGC relative to equilibrium HSGC obtained from an example. DETAILED DESCRIPTION OF THE INVENTION

[0021] Systems and methods for devolatilizing low viscosity polymers having low melt strength are provided herein. It has been unexpectedly and surprisingly found that low viscosity polymers having low melt strength can be devolatilized to equilibrium VOC at the conventional operating temperatures and pressures of a final stage devolatilizer. According to one or more embodiments provided herein, the low viscosity (i.e., Brookfield viscosity less than 40,000 cP, melt flow rate (MFR) of 500 to 40,000 g / 10 minutes (ASTM D1238) and / or less than 200 Pa-s (at 190 °C and 0.1 s -1Zero shear viscosity (measured at a frequency) and polymers with a low molecular weight (i.e., Mw less than 62,000 g / mol) can be adequately devolatilized by generating foam or numerous bubbles during the final stage of devolatilization. Controlled foaming can be generated and maintained to reduce the VOC of the polymer to the lowest concentration thermodynamically possible at a given temperature and pressure. The so-called "foam" refers to a light, foamy substance in which the process solvent to be volatilized, dissolved in a low-viscosity polymer with low melt strength, forms bubbles or gas pockets in or on the polymer surface, where those bubbles or gas pockets contain hydrocarbons that are evaporating.

[0022] Low-viscosity polymers with low melt strength have a Brookfield viscosity of 300 cP to 40,000 cP, a melt flow rate (MFR) of 500 to 40,000 (g / 10 min) (ASTM D1238), and / or a zero shear viscosity of less than 200 Pa-s (measured at 190 °C and 0.1 s -1 frequency). The Brookfield viscosity can also be in the range of about 300 cP, 400 cP, 600 cP, or 1,000 cP at the lower limit to 3,000 cP, 10,000 cP, 15,000 cP, or 40,000 cP at the upper limit. The MFR can also be in the range of about 500 g / 10 min, 1,000 g / 10 min, or 2,000 g / 10 min at the lower limit to 3,000 g / 10 min, 15,000 g / 10 min, 25,000 g / 10 min, or 40,000 g / 10 min at the upper limit. Low-viscosity polymers with low melt strength also have a low weight-average molecular weight (Mw), e.g., less than 62,000 g / mol, less than 56,000 g / mol, less than 46,000 g / mol, less than 36,000 g / mol, or less than 26,000 g / mol.

[0023] It has unexpectedly and surprisingly been found that low viscosity polymers having a Brookfield viscosity of less than 40,000 cP, an MFR of greater than 500 g / 10 min and / or a zero shear viscosity of less than 200 Pa-s and having a low melt strength can be sufficiently devolatilized to an equilibrium VOC concentration which will be the lowest VOC concentration at a given temperature and pressure. Such low viscosity polymers can be elastomers, plastomers, thermoplastics, thermoplastic elastomers or other types of elastic polymers. Such low viscosity polymers can also be polyolefins, such as polypropylene, propylene-based polyolefins, polyethylene, ethylene-based polyolefins, polystyrene or combinations thereof. Preferred polyolefins are copolymers or terpolymers with dienes or other polar comonomers, including silane-modified polyethylene, ethylene-vinyl acetate, ethylene acrylate, organic acid-modified polyethylene. The low viscosity polymers can be propylene-rich (>50 wt% C3) or ethylene-rich (>50 wt%), where the comonomer units are derived from ethylene or higher alpha-olefins from C4 to C40, with random or block modes of insertion.

[0024] It should be understood that the systems and methods described herein are equally applicable to devolatilizing polymers derived from any liquid phase polymerization process. For example, the polymer to be devolatilized can be derived from high pressure fluid, slurry, bulk or solution phase polymerization processes or combinations thereof. However, for simplicity and ease of description, the embodiments provided herein for devolatilizing low melt strength polymers will be further described with reference to polymers prepared using solution polymerization techniques.

[0025] It should also be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, and / or functions of the present invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are provided only as examples and are not intended to limit the scope of the present invention. Additionally, the present disclosure may repeat reference numerals and / or letters in the various exemplary embodiments and in the figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself indicate a relationship between the various exemplary embodiments and / or configurations discussed in the figures. Further, the exemplary embodiments provided below can be combined in any manner, i.e., any element from one exemplary embodiment can be used in any other exemplary embodiment without departing from the scope of the disclosure.

[0026] Additionally, certain terms are used in the following specification and claims to refer to particular components. As those skilled in the art will appreciate, various entities may refer to the same component by different names, and thus, unless specifically defined otherwise herein, the naming convention for the elements described herein is not intended to limit the scope of the present invention. Further, the naming convention used herein is not intended to distinguish components that have different names but different functions.

[0027] In the following discussion and claims, the terms "comprising" and "including" are meant to be open-ended and should thus be interpreted as meaning "including but not limited to". The phrase "consisting essentially of" means that the described / claimed composition does not contain any other components that would substantially change its properties by more than ±5% of that property, and in any case, does not contain any other components to a level greater than 3 mass%.

[0028] The term "or" is intended to cover both exclusive and inclusive cases, i.e., "A or B" is intended to be synonymous with "at least one of A and B", unless otherwise clearly specified herein.

[0029] The indefinite articles "a" and "an" refer to the singular form (i.e., "one") and plural referents (i.e., one or more), unless the context clearly dictates otherwise. For example, embodiments using "an olefin" include embodiments in which one, two, or more olefins are used, unless otherwise specified or the context clearly indicates that only one olefin is used.

[0030] 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 and mean parts per million by weight. Unless otherwise specified, all concentrations are expressed based on the total amount of the composition under discussion.

[0031] The term "polymer" refers to any two or more identical or different repeating / monomeric units or units. The term "homopolymer" refers to a polymer having the same units. The term "copolymer" refers to a polymer having two or more units that are different from each other and includes terpolymers and the like. The term "terpolymer" refers to a polymer having three monomer units that are different from each other. The term "different" refers to units that differ from each other by at least one atom or are isomerically different. Similarly, the definition of polymer used herein includes homopolymers, copolymers, and analogs. For example, when a copolymer is said to have a "propylene" content of 10 wt% to 30 wt%, it should be understood that the repeating / monomeric 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.

[0032] As used herein, "Mn" refers to the number-average molecular weight of the different polymers in the polymeric material, "Mw" refers to the weight-average molecular weight of the different polymers in the polymeric material, and "Mz" refers to the z-average molecular weight of the different polymers in the polymeric material. The terms "molecular weight distribution" (MWD) and "polydispersity index" (PDI) are used interchangeably and refer to the ratio of Mw to Mn. Unless otherwise stated, all molecular weights (e.g., Mw, Mn, Mz) are reported in g / mol.

[0033] The nomenclature of the elements and their groups used herein follows the periodic table used by the International Union of Pure and Applied Chemistry after 1988. An example of the periodic table is shown on the inner page of the cover of the sixth edition of Advanced Inorganic Chemistry edited by F. Albert Cotton et al. (John Wiley & Sons, Inc., 1999).

[0034] As used herein, "polymer" can be used to refer to homopolymers, copolymers, interpolymers, terpolymers, etc. When it is said that a polymer contains monomers, the monomers are present in the polymer in the polymerized form of the monomers or in the form of derivatives of the monomers. Thus, when a polymer is said to contain a certain percentage (e.g., weight %) of monomers, the monomer percentage is based on the total amount of monomer units in all polymer components of the composition or blend. That is, a polymer containing 30% by weight of ethylene and 70% by weight of propylene is a polymer in which 30% of the polymer is units derived from ethylene and 70% of the polymer is units derived from propylene.

[0035] As used herein, "solution polymerization" refers to a polymerization method that occurs in the presence of a liquid polymerization system (such as an inert solvent or a monomer (one or more) or a blend thereof), in which the resulting polymer is dissolved. Solution polymerization includes homogeneous liquid polymerization systems in a reactor. A homogeneous polymerization method is generally a method in which at least 90% by weight of the product is soluble in the reaction medium, such as at least 95% by weight, at least 98% by weight, or 100% by weight. The temperature of the liquid polymerization system is below its supercritical or pseudo supercritical temperature. Therefore, solution polymerization is carried out at a temperature and / or pressure below the supercritical temperature of the system.

[0036] As used herein, "polymer concentration" is the weight percentage of the polymer relative to the total weight of the solution mixture.

[0037] As used herein, "monomer concentration" is the weight percentage of the monomer relative to the total weight of the solution mixture.

[0038] The "melt flow rate" used in this article is the ability of a polymer to flow within a finite time interval. The melt flow rate of a polymer is calculated as the weight passing through a melt flow tester at a standard temperature / 10 minutes.

[0039] Figure 1 Depicted is an illustrative process flow diagram of a devolatilization unit 100 in accordance with one or more embodiments provided herein. The devolatilization unit 100 ("Devol unit") includes any number of separators or flush drums (three 110, 120, 130 are shown). The reactor effluent enters the first flash drum 110 via a stream or conduit 102. The reactor effluent stream 102 is a polymer solution and contains varying amounts of polymer, solvent, and other unreacted monomers. The reactor effluent can have a polymer weight fraction of about 1 wt% to about 75 wt%, such as about 2 wt% to about 50 wt%, or about 5 wt% to about 40 wt%, or about 7 wt% to about 35 wt%, and the balance up to 100% will be volatile organic compounds ("VOCs"). The VOCs in the reactor effluent stream 102 are the solvent, any unreacted monomers, and any other free hydrocarbons.

[0040] Each flash drum 110, 120, 130 operates at a certain temperature and pressure to optimally achieve gas - liquid or liquid - liquid separation therein. For example, the first flash drum 110 can operate at a temperature of 100 to 160 °C and a pressure of 70 to 700 psig. The second flash drum 120 can operate at a temperature of 130 to 180 °C and a pressure of 30 to 60 psig. The third flash drum 130 can operate at a temperature of 130 °C to 220 °C and a pressure of 10 to 50 torr.

[0041] Within the first flash vessel or flash unit 110, most of the unreacted monomers, comonomers, and solvent (i.e., volatiles) are separated from the polymer. Within the second flash vessel or flash unit 120, the temperature and pressure conditions are changed to allow further separation of the remaining volatiles from the polymer. And within the third flash vessel or flash unit 130, the temperature and pressure conditions are again changed to further separate any residual volatiles from the polymer to meet the desired specification of volatiles in the parts - per - million range.

[0042] For example, the polymer stream 114 that leaves the first separation drum 110 and enters the second flash drum 120 can contain from 30 wt% to 60 wt% polymer and from 40 - 70 wt% volatile organic compounds ("VOC"). The polymer stream 124 that leaves the second flash drum 120 and enters the third flash drum 130 can contain from 85 wt% to 95 wt% polymer and from 5 - 15 wt% volatile organic compounds ("VOC"). The polymer stream 134 that leaves the third flash drum 130 can contain polymer having less than 2,000 ppmw volatile organic compounds ("VOC"), such as less than 1,800 ppmw, 1,600 ppmw, 1,500 ppmw, 1,200 ppmw, 1,000 ppmw, 500 ppmw, or 200 ppmw volatile organic compounds ("VOC").

[0043] The overhead streams 118, 128, 138 from each of the separation drums 110, 120, 130 contain VOCs that have been separated from the polymer. Each overhead stream 118, 128, 138 can be reused and / or recycled to the polymerization process. For example, the first overhead stream 118 that leaves the first flash drum 110 can be sent to a solvent drum (not shown) and recycled for use in the polymerization system. The second overhead stream 128 that leaves the second flash drum 120 can be sent to a heavy tower (not shown) for further separation and recycled for use in the polymerization system. The third overhead stream 138 that leaves the third flash drum 130 can be sent to a separation tower (not shown) for further separation and recycled for use in the polymerization system. The devolatilized polymer stream 134 that leaves the third flash drum 130 is then cooled and pelletized.

[0044] Figure 2 depicts an enlarged schematic view of an exemplary vacuum flash drum that can be used as the third flash drum 130 according to one or more embodiments provided herein Figure 1 as depicted in. The flash drum 130 includes a housing 210, a polymer inlet 215, a polymer outlet 225, and a volatiles outlet 235.

[0045] Volatiles evaporated from the polymer exit the housing 210 through the volatiles outlet 235. A collection system, such as a condensation system (not shown), can also be coupled to the volatiles outlet 235 to collect the volatiles for disposal, recycling, and / or recirculation. The polymer outlet 225 contains the devolatilized polymer and directs the polymer to other downstream processing, such as a pelletizer, an extruder, or other processing systems.

[0046] Although not shown, the housing 210 provides the required temperature and pressure environment to devolatilize the polymer within the flash drum 130. To control the pressure within the flash drum 130, a pressure control valve is coupled to the volatiles outlet 235. External and / or internal heat exchangers are used to maintain the desired temperature within the separator 130. The heat transfer fluid can be high-pressure steam or heating oil (e.g., hydrocarbons such as mineral oil, etc.), or a synthetic medium. The housing 210 may also include resistance heating elements (also not shown) to control the temperature.

[0047] The housing 210 may optionally include one or more devolatilization plates (three plates 260, 262, 264 are shown). Each devolatilization plate 260, 262, 264 contains a plurality of cavities or holes (not shown) formed therethrough that permit fluid communication between the plates within the housing 210. The distance between each devolatilization plate 260, 262, 264 may be the same or may vary. Compared to no devolatilization plates, the devolatilization plates allow and provide additional residence time and polymer solution surface renewal to enhance mass transfer of volatiles from the polymer. The residence time on each devolatilization plate 260, 262, 264 may vary and may be from about 5 seconds to 10 minutes, or 10 seconds to 5 minutes. The residence time may also be in the range from a lower limit of about 5 seconds, 10 seconds, or 30 seconds to an upper limit of about 1 minute, 5 minutes, or 10 minutes. For additional design and operating details of suitable devolatilization plates, see U.S. Publication No. 2021 / 0221925A1.

[0048] Figure 3 Depicted is an enlarged schematic view of a polymer solution feed assembly 300 for entering Figure 2 the flash drum 130 depicted herein. The polymer solution feed assembly 300 holds the solvent and unreacted monomers entrained within the polymer melt. The feed assembly 300 may include a control valve 305 and a length of tubing or other conduit 310 downstream of the control valve 305. The downstream separator conduit 310 is connected to the control valve 305 at one end 312 ("first end") thereof and projects through the drum housing 210 at its opposite end 314 ("second end"), as Figure 2 shown. The downstream conduit 310 defines a feed chamber 325 for feeding or otherwise delivering the polymer solution into the flash drum 130.

[0049] The downstream conduit 310 and thus the feed chamber 325 therein can have any suitable shape and size. For example, the cross-section of the downstream conduit 310 and the feed chamber 325 can resemble any shape, such as circular, oval, elliptical, square, rectangular, or other polygonal shapes. The inner diameter of the pilot-scale downstream conduit 310 can range from 5 mm, 10 mm, or 15 mm to 30 mm, 35 mm, or 40 mm. The length of the downstream conduit 310 can be from 5 cm to 50 cm.

[0050] The inner diameter of the downstream conduit 310 can be constant from one end 312 to the other end 314. In some embodiments, the inner diameter of the downstream conduit 310 can vary at one or more locations along its entire length, thereby providing one or more variable chokes within the chamber 325.

[0051] Referring Figure 2 and Figure 3 , the polymer solution (vapor 215) entering the drum 130 has a higher pressure before reaching the pressure control valve 305, where its pressure is reduced. The pressure drop across the valve 305 can range from a lower limit of about 50 psig (2586 torr), 100 psig (5,171 torr), or 150 psig (7,757) to an upper limit of about 200 psig (10,343 torr), 300 psig (15,515 torr), or 400 psig (20,686 torr). The drum 130 is maintained at a vacuum pressure (i.e., less than 0 psig) using a vacuum system (not shown). The downstream conduit 310 after the control valve 305 carries the polymer solution to the drum 130 and will also have a vacuum pressure, as there is a minimal pressure drop along the open end 314 of the conduit 310. Due to this pressure differential, volatiles will evaporate as they pass through the control valve 305, thereby creating a two-phase fluid within the chamber 325 of the conduit 310, namely liquid polymer and vapor volatiles. This significant pressure drop across the valve 305 results in nucleation and foaming within the chamber 325, which has an open fluid communication and further feeds into the drum 130.

[0052] To generate foam, the evaporated volatiles need to contact the liquid polymer within the chamber 325 for a predetermined amount of time, i.e., residence time, before being released into the drum 130. This residence time is a function of the volumetric flow rate of the polymer solution and the length and diameter of the conduit 310. Under vacuum Devol conditions, a suitable residence time can range from a lower limit of about 0.2, 0.4, or 0.6 seconds to an upper limit of 10, 15, or 20 seconds.

[0053] The devolatilization vessel temperature can be in the range of 130 °C to 210 °C, and the pressure can be less than 100 Torr, 90 Torr, 80 Torr, or 70 Torr. A blowing agent is not required or needed. Up to 3 wt% of one or more stripping agents (light gases) can be added to the polymer solution to improve VOC separation. Suitable stripping agents include C2-C5 olefins, C2-C5 alkanes, steam, carbon dioxide, or any combination thereof.

[0054] As described above, the volume and diameter of the conduit 310 are important design parameters for inducing foaming under the correct process conditions. This means that for a specific diameter of the conduit 310, the length of the conduit 310 can be adjusted to define the volume of the chamber 325, and vice versa. It is also important to provide sufficient shear rate between the vapor and the liquid within the chamber 325 of the conduit 310. This shear rate is a function of the volumetric flow rate of the polymer solution and the diameter of the conduit 310. Under vacuum stage conditions, a suitable shear rate for the low-viscosity polymers described herein can be in the range of 2,000 to 200,000 1 / s.

[0055] Figure 4 Depicts an alternative polymer solution feed assembly 400 for entering Figure 2 the flash drum 130 depicted in the enlarged schematic view according to one or more embodiments provided herein. This alternative polymer solution feed assembly 400 is similar to Figure 3 the feed assembly 300, but is different at its second end 414, which is open to the interior of the drum housing 210. The second end 414 of the assembly 400 has a reduced inner diameter ("D") 420 to restrict the fluid flow therethrough, thereby increasing the pressure drop from the assembly 400 to the flash drum 130. The diameter 420 can range from a lower limit of about 0.5 mm, 1.0 mm, or 1.25 mm to an upper limit of about 1.5 mm, 2.0 mm, or 2.5 mm.

[0056] Figure 5 Depicts a schematic view of a vacuum flash drum 130 according to one or more embodiments provided herein, which can be configured to utilize multiple feed assemblies 300, 400. In such an embodiment, any number of feed assemblies 300, 400 can be used, either individually or in combination with each other. The different feed assemblies 300, 400 can be located at any position along the sidewall 510 or the head 520 of the drum 130. In Figure 5In it, the top or upper feed assembly is shown as being of the feed assembly 300 type, and the bottom or lower feed assembly is shown as being of the feed assembly 400 type, but any number and configuration of assemblies 300, 400 can be used. For example, the flash drum 130 can be configured with one or more feed assemblies 300 and one or more feed assemblies 400 such that the polymer feed stream 215 is split or otherwise separated to feed into the flash drum 130 through any one or more of the feed assemblies 300 and / or feed assemblies 400. The flash drum 130 can also be configured with two or more feed assemblies 300 and / or two or more feed assemblies 400 such that the polymer feed stream 215 can be split to feed into the flash drum 130 through any combination of two or more feed assemblies 300 and / or two or more feed assemblies 400. As described above, when two or more assemblies 300, 400 are used, each assembly can be of the same type (300 or 400) or a combination of types (300 and 400), and the assemblies can be arranged at any position along the sidewall 510 or the top cover 520 of the drum 130.

[0057] The number and location of the feed assembly 300, 400 types can be determined by the polymer itself. For example, a polymer having a Brookfield viscosity of less than 40,000 cP will favor the feed assembly 300, and a polymer having a Brookfield viscosity of 40,000 cP or higher will favor the feed assembly 400. To have full production capacity, which means the ability to manufacture different polymer types and different polymer grades using the same Devol unit, the types of assemblies 300, 400 can be easily swapped or replaced.

[0058] According to one or more embodiments provided herein, the systems and methods for devolatilizing low-viscosity polymers can be used with any liquid-phase polymerization method. Solution polymerization methods are preferred. Suitable solution polymerization methods are generally described in more detail in U.S. Patent Nos. 9,359,535, 7,470,118, 7,226,553, and 7,033,152, which are hereby incorporated by reference in their entireties. WO 2017 / 058385 A1 describes a solution polymerization method using a single or multiple coil heat exchanger system for the continuous polymerization of C2 to C40 olefins, which can also be used and is also incorporated by reference in its entirety herein.

[0059] The polymerization process can be carried out under conditions including the following temperatures: 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 350 psi to about 1800 psi (about 2,413 to about 12,411 kPa), preferably 200 psi to 1000 psi (about 1379 kPa to 6895 kPa), preferably 300 psi to 600 psi (about 2068 kPa to 4137 kPa). Preferably, the pressure is about 450 psi (about 3103 kPa).

[0060] Hydrogen can be present at a partial pressure of 0.001 psig to 50 psig (0.007 kPa to 345 kPa), preferably 0.01 psig to 25 psig (0.07 kPa to 172 kPa), preferably 0.1 psig to 10 psig (0.7 kPa to 70 kPa) during the polymerization process.

[0061] Catalyst systems suitable for use in combination with the methods and systems provided herein include one or more metallocene catalysts and other single-site catalysts. Other suitable catalysts include, but are not limited to, Ziegler-Natta catalyst compounds, late transition metal catalyst compounds, and other non-metallocene catalyst compounds. Heteroaryl ligand catalyst compounds of non-metallocene metal centers are described in detail in PCT Patent Publication Nos. WO 02 / 38628, WO 03 / 040095 (pages 21 to 51), WO 03 / 040201 (pages 31 to 65), WO 03 / 040233 (pages 23 to 52), WO 03 / 040442 (pages 21 to 54), WO 2006 / 38628, and U.S. Patent Application Publication No. 2008 / 0153997, each of which is incorporated herein by reference.

[0062] As described above, the low-viscosity polymer can be an elastomer, plastomer, thermoplastic, thermoplastic elastomer, or other type of elastic polymer. The low-viscosity polymer can also be a polyolefin, such as polypropylene, propylene-based polyolefin, polyethylene, ethylene-based polyolefin, polystyrene, or a combination thereof. Preferred polyolefins are copolymers or terpolymers with dienes or other polar comonomers, including silane-modified polyethylene, ethylene-vinyl acetate, ethylene acrylate, and organic acid-modified polyethylene. The low-viscosity polymer can be rich in propylene (>50 wt% C3) or rich in ethylene (>50 wt%), where the comonomer units are derived from ethylene or higher α-olefins from C4 to C40, with a random or block mode of insertion.

[0063] In one or more embodiments, the low-viscosity polymer can be derived from any monomer having one or more non-conjugated aliphatic double bonds (one or more) and two or more carbon atoms. Examples of monomers include substituted or unsubstituted C2 to C 40 α-olefins. For example, suitable monomers can be, but are not limited to, one or more α-olefins (such as ethylene, propylene, butene-1, hexene-1, octene-1, decene-1, and dodecene-1), substituted olefins (such as styrene, p-methylstyrene, and vinylcyclohexane), non-conjugated dienes (such as vinylcyclohexene), α,ω-dienes (such as 1,5-hexadiene and 1,7-octadiene), cycloolefins (such as cyclopentene, cyclohexene, and cyclohexadiene), norbornene, etc., and any combination thereof. Additional monomers include 4-methylpentene-1, 3-methylpentene-1, 3,5,5-trimethylhexene-1, and 5-ethylnonene-1.

[0064] Aromatic-containing monomers having up to 30 carbon atoms can be used. Suitable aromatic-containing monomers have at least one aromatic structure, advantageously one to three, more advantageously a phenyl, indenyl, fluorenyl, or naphthyl structural moiety. The aromatic-containing monomers also contain at least one polymerizable double bond such that after polymerization, the aromatic structure will be pendant from the polymer backbone. The aromatic-containing monomers can be further substituted by one or more hydrocarbon groups, including but not limited to C1 to C 10 alkyl groups. Additionally, two adjacent substitutions can be linked to form a ring structure. Advantageous aromatic-containing monomers contain at least one aromatic structure attached to a polymerizable ethylenic structural moiety. Particularly advantageous aromatic monomers include styrene, α-methylstyrene, p-alkylstyrene, vinyltoluene, vinylnaphthalene, allylbenzene, and indene, especially styrene, p-methylstyrene, 4-phenyl-butene-1, and allylbenzene.

[0065] Monomers containing non-aromatic cyclic groups can be used. These monomers can contain up to 30 carbon atoms. Suitable monomers containing non-aromatic cyclic groups advantageously have at least one polymerizable ethylenic group that is pendant to or a part of the cyclic structure. The cyclic structure can be further substituted by one or more hydrocarbon groups, such as but not limited to C1 to C 10 alkyl groups. Advantageous monomers containing non-aromatic cyclic groups include vinylcyclohexane, vinylcyclohexene, vinylnorbornene, ethylidene norbornene, cyclopentadiene, cyclopentene, cyclohexene, cyclobutene, vinyladamantad, etc.

[0066] Diene monomers (one or more) can also be used. Advantageous diene monomers include any hydrocarbon structure having at least two unsaturated bonds, advantageously, C4 to C 30, wherein at least two of the unsaturated bonds are easily introduced into the polymer by a stereospecific or non-stereospecific catalyst(s). Further advantageously, the diene monomer is selected from α-ω diene monomers (e.g., divinyl monomers). More advantageously, the diene monomer is a linear divinyl monomer, most advantageously those containing 4 to 30 carbon atoms. Examples of such dienes include butadiene, pentadiene, hexadiene, heptadiene, octadiene, nonadiene, decadiene, undecadiene, dodecadiene, tridecadiene, tetradecadiene, pentadecadiene, hexadecadiene, heptadecadiene, octadecadiene, nonadecadiene, eicosadiene, heneicosadiene, docosadiene, tricosadiene, tetracosadiene, pentacosadiene, hexacosadiene, heptacosadiene, octacosadiene, nonacosadiene, triacontadiene. Particularly advantageous 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 polybutadiene (weight average molecular weight less than 1000 g / mol). Advantageous cyclic dienes include cyclopentadiene, vinylnorbornene, norbornadiene, ethylidene norbornene, divinylbenzene, dicyclopentadiene, or dienes with higher rings with or without substituents at various ring positions.

[0067] In one or more embodiments, the low-viscosity polymer is a propylene-based elastomer containing greater than 50 wt%, preferably greater than 60 wt%, more preferably greater than 65 wt%, even more preferably greater than 75 wt% and up to 99 wt% of propylene-derived units, based on the total weight of the polymer. In some preferred embodiments, based on the weight of the propylene-based elastomer, the propylene-based elastomer contains 75 wt% to 95 wt%, more preferably 75 wt% to 92.5 wt%, even more preferably 82.5 wt% to 92.5 wt%, and most preferably 82.5 wt% to 90 wt% of propylene-derived units. Accordingly, units or comonomers derived from ethylene or at least one of C4 to C 10 α-olefins may be present in an amount of 5, or 10 or 14 wt% to 22 or 25 wt% based on the weight of the elastomer. The comonomer content can be adjusted such that the propylene-based elastomer can have a heat of fusion of 100 J / g, 90 J / g, 85 J / g, 80 J / g, 75 J / g, 70 J / g or 65 J / g or lower, a melting point (T m ) of 100 °C or 90 °C or lower, and a crystallinity of 2% to 65% of isotactic polypropylene.

[0068] In one or more embodiments, the low viscosity polymer is an ethylene-based elastomer containing greater than 50 wt%, preferably greater than 60 wt%, more preferably greater than 65 wt%, even more preferably greater than 75 wt% and up to 99 wt% of ethylene-derived units, based on the total weight of the polymer. In some preferred embodiments, based on the total weight of the polymer, the ethylene-based elastomer has from 75 wt% to 95 wt%, more preferably from 75 wt% to 92.5 wt%, even more preferably from 82.5 wt% to 92.5 wt%, and most preferably from 82.5 wt% to 90 wt% of ethylene-derived units. Accordingly, the units or comonomers derived from C3 to C 10 α-olefins can be present in an amount from a lower limit of 5, 10 or 15 wt% of the polymer to an upper limit of about 20, 25 or 30 wt% of the polymer.

[0069] The low viscosity polymer can be branched or unbranched, as determined by the g' average from GPC-4D measurements. A typical GPC-4D curve has log M vs. g', and is used to estimate the g' average based on the average across molecular weights. The branching index g' average ranges from 1 to 0, where 1 is linear (no branching) and 0 is fully branched. In one or more embodiments, the low viscosity polymer can have a g' of less than 0.99, less than 0.98, less than 0.97, less than 0.96, less than 0.95 or less than 0.90.

[0070] In certain embodiments, an inert solvent can be used during the polymerization process. The solvent will form part of the reactor effluent. Examples of inert solvents include straight-chain, branched-chain, cyclic, cycloaliphatic, halogenated or aromatic hydrocarbons and mixtures thereof. Examples of straight-chain and branched-chain hydrocarbons include isobutane, butane, pentane, isopentane, hexane, isohexane, heptane, octane, dodecane and mixtures thereof. Examples of cyclic and cycloaliphatic hydrocarbons include cyclohexane, cycloheptane, methylcyclohexane, methylcycloheptane and mixtures thereof. Examples of halogenated hydrocarbons include fluorinated C4-C10 alkanes and chlorobenzene. Examples of aromatic compounds include benzene, toluene, mesitylene and xylene. Additional embodiments

[0071] Other embodiments provided herein include any one or more of the following numbered embodiments:

[0072] Embodiment 1: A method for devolatilizing a low-viscosity polymer, comprising: providing a reaction mixture comprising a polymer and one or more volatiles, wherein the one or more volatiles comprise one or more unreacted monomers and at least one hydrocarbon solvent; separating the reaction mixture in a first separator into a polymer-rich phase and a polymer-lean phase; separating the polymer-rich phase in a second separator into a vapor hydrocarbon phase and a concentrated polymer phase; removing at least a portion of the volatiles from the concentrated polymer phase in a third separator to provide a devolatilized polymer; and providing a residence time of about 0.2 seconds to 10 seconds in a separator conduit located between the second separator and the third separator.

[0073] Embodiment 2: The method according to Embodiment 1, wherein the polymer comprises propylene and up to 20 wt% of ethylene and / or one or more monomers having 4 or more carbon atoms.

[0074] Embodiment 3: The method according to Embodiment 1 or 2, wherein the polymer has a Brookfield viscosity of 300 cP to 40,000 cP or a zero-shear viscosity of less than 200 Pa-s when measured at 190 °C and 0.1 s -1 frequency.

[0075] Embodiment 4: The method according to any one of Embodiments 1 to 3, wherein the polymer has a weight-average molecular weight (Mw) of less than 62,000 g / mol as determined by GPC or a melt flow rate (MFR) of 500 to 40,000 g / 10 min as measured by ASTM D1238.

[0076] Embodiment 5: The method according to any one of Embodiments 1 to 4, wherein the concentrated polymer phase has a volatile concentration of 4 wt% to 15 wt% based on the total weight of the concentrated polymer phase.

[0077] Embodiment 6: The method according to any one of Embodiments 1 to 5, wherein the separator conduit is configured to provide a shear rate of 2,000 to 200,000 1 / s.

[0078] Embodiment 7: The method according to any one of Embodiments 1 to 6, wherein the devolatilized polymer has a volatile concentration of less than 600 ppmw based on the total weight of the concentrated polymer phase.

[0079] Embodiment 8: A method for devolatilizing a low-viscosity polymer, comprising: providing a reaction mixture comprising a polymer having a Brookfield viscosity of less than 40,000 cP and a weight-average molecular weight (Mw) of less than 62,000 g / mol as determined by GPC and one or more volatiles, wherein the one or more volatiles comprise one or more unreacted monomers and at least one hydrocarbon solvent; separating the reaction mixture in a first separator into a polymer-rich phase and a polymer-lean phase; separating the polymer-rich phase in a second separator into a vapor hydrocarbon phase and a concentrated polymer phase; removing at least a portion of the volatiles from the concentrated polymer phase in a third separator to provide a devolatilized polymer; and providing a residence time of about 0.2 seconds to 10 seconds in a separator conduit located between the second separator and the third separator.

[0080] Embodiment 9: The method according to Embodiment 8, wherein the polymer comprises propylene and up to 20 wt% ethylene and / or one or more monomers having 4 or more carbon atoms.

[0081] Embodiment 10: The method according to Embodiment 8 or 9, wherein the polymer has a Brookfield viscosity of less than 15,000 cP.

[0082] Embodiment 11: The method according to any one of Embodiments 8 to 10, wherein the concentrated polymer phase has a volatile concentration of 4 wt% to 15 wt% based on the total weight of the concentrated polymer phase.

[0083] Embodiment 12: The method according to any one of Embodiments 8 to 11, wherein the separator conduit is configured to provide a shear rate of 2,000 to 200,000 1 / s under the conditions of the third separator.

[0084] Embodiment 13: The method according to any one of Embodiments 8 to 12, wherein the devolatilized polymer has a volatile concentration of less than 600 ppmw based on the total weight of the concentrated polymer phase.

[0085] Embodiment 14: A method for devolatilizing a low-viscosity polymer, comprising: providing a reaction mixture comprising: a polymer having a Brookfield viscosity of less than 40,000 cP, a weight-average molecular weight (Mw) of less than 62,000 g / mol as determined by GPC, and a melt flow rate (MFR) of 500 - 40,000 g / 10 min (ASTM D1238), and one or more volatiles, said one or more volatiles comprising one or more unreacted monomers and at least one hydrocarbon solvent; separating the reaction mixture in a first separator into a polymer-rich phase and a polymer-lean phase; separating the polymer-rich phase in a second separator into a vapor hydrocarbon phase and a concentrated polymer phase; removing at least a portion of the volatiles from the concentrated polymer phase in a third separator to provide a devolatilized polymer; and providing a residence time of about 0.2 seconds to 10 seconds in a separator conduit located between the second separator and the third separator under the third separator conditions.

[0086] Embodiment 15: The method according to Embodiment 14, wherein the separator conduit is configured to provide a shear rate of 2,000 to 200,000 1 / s under the third separator conditions.

[0087] Embodiment 16: The method according to Embodiment 14 or 15, wherein the devolatilized polymer has a volatile concentration of less than 600 ppmw based on the total weight of the concentrated polymer phase.

[0088] Embodiment 17: The method according to any one of Embodiments 14 to 16, wherein the polymer is 85 - 99 wt% propylene-derived units and 1 - 15 wt% ethylene-derived units.

[0089] Embodiment 18: The method according to any one of Embodiments 14 to 17, wherein the polymer has a zero-shear viscosity of less than 200 Pa-s when measured at 190 °C and 0.1 s -1 frequency.

[0090] Embodiment 19: The method according to any one of Embodiments 14 to 18, wherein the polymer has a weight-average molecular weight (Mw) of less than 46,000 g / mol.

[0091] Embodiment 20: A devolatilization system for a low-viscosity polymer, comprising: a first separator that separates a reaction mixture comprising a polymer and one or more volatiles into a polymer-rich phase and a polymer-lean phase, wherein the one or more volatiles comprise one or more unreacted monomers and at least one hydrocarbon solvent; a second separator that separates the polymer-rich phase into a vapor hydrocarbon phase and a concentrated polymer phase; a third separator that removes at least a portion of the volatiles from the concentrated polymer phase; and a separator conduit located between the second separator and the third separator, the separator conduit configured to provide a residence time therein of from about 0.2 seconds to 10 seconds. Specific embodiments Examples:

[0092] The foregoing discussion may be further described with reference to the following non-limiting examples. Three low-viscosity polymers having a viscosity range of 1,100 to 11,500 cP were devolatilized in a vacuum flash vessel. In all three cases, the inlet polymer solution feed had a volatile concentration of 4 to 10 wt%. The polymers were propylene-ethylene elastomers ("PBE") obtained from ExxonMobil Product Solutions Company. All three polymers had an ethylene content of 6 wt% and the balance propylene and are summarized in Table 1 below.

[0093] Table 1: The physical properties of the three PBEs are summarized as follows:

[0094] A range of temperatures and vacuum pressures were tested in each case. The devol pressure range was 20 - 100 torr and the temperature range was 135 - 165 °C. Two polymer inlet feed configurations were used. The first configuration was an open-ended conduit feed assembly 300 and the second configuration was a choke conduit feed assembly 400. In the first open-ended configuration, the pressure in the conduit section downstream of the control valve was equal to the flash drum pressure and two phases (liquid and vapor) were observed in the conduit chamber. In the second choke configuration, the pressure in the conduit section downstream of the control valve was higher than the drum pressure and higher than the vapor pressure of the polymer solution. Only a single liquid phase was observed in the inlet pipe chamber such that any evaporation of the volatiles occurred after the solution left the choke and entered the flash drum. The results are reported in Tables 2 and 3 below.

[0095] Table 2: Process conditions and results for the devolatilization of each polymer using the open-ended feed configuration 300

[0096] Table 3: Process conditions and results for the devolatilization of each polymer using the choke feed configuration 400

[0097] Figure 6 Plots of VOC HSGC relative to equilibrium HSGC obtained from the two inlet feed configurations described are shown. This shows the measured VOCs and the calculated equilibrium VOCs for the range of process operating windows tested (i.e., 20 - 100 Torr and 135 - 165 °C). This HSGC data shows the positive effect of foaming on reducing the VOC content of the polymer and approaching the equilibrium VOC. As Figure 6 shown, devolatilizing the polymer using the end - open inlet tube configuration results in foaming and the polymer having a VOC at or near equilibrium. In contrast, devolatilizing the same polymer using the choked inlet tube configuration results in a much higher amount of VOC in the polymer. Based on this data, and not wishing to be bound by theory, surprisingly and unexpectedly, it appears that the foaming nucleation and foaming intensity are functions not only of the initial volatile concentration, temperature, and pressure (degree of superheat), but also of the shear rate and residence time (i.e., volatile polymer exposure time) within the feed conduit chamber 325. Test Procedures

[0098] In the foregoing examples, the following test methods and procedures were used:

[0099] Head Space Gas Chromatography (HSGC) was used to measure the volatile content of the polymer pellets. In this method, 2 gr of pellets were placed in a 20 ml finger tube. The finger tube was heated at 130 °C for 35 minutes. Then the headspace of the finger tube was injected into the GC.

[0100] The shear rate within the conduit 310 was calculated using the Hagen - Poiseuille equation: Shear rate (1 / s) = 4Q / πr 3 , where Q is the polymer solution volumetric flow rate under vacuum Devol conditions and r is the tube radius. The so - called "vacuum Devol conditions" refer to the same temperature and pressure within the third and / or final flash drum 130.

[0101] The Brookfield viscosity was measured at 190 °C. The rotor was rotated at 20 rpm to measure the viscosity, and data was collected every 30 seconds for 15 minutes. The torque was maintained at the 45 - 55% level during the test.

[0102] The MFR was measured according to (ASTM D1238). For low viscosities that are difficult to measure, the MFR was calculated based on the following relationship: MFR (ASTM D1238) = 9591437*B.V -0.93 ,(R 2= 0.99), where B.V. is the Brookfield viscosity.

[0103] The distributions and moments of molecular weights (Mw, Mn, Mz, Mw / Mn, Mz / Mn, etc.) and comonomer contents (C2, C4, C8) are determined using high-temperature gel permeation chromatography (Polymer Char GPC-IR) equipped with a multi-channel bandpass filter-based infrared detector IR5, an 18-angle light scattering detector, and a viscometer. Three Agilent PLgel 10μm Mixed-B LS columns are used to provide polymer separation. The detailed analysis principles and methods for molecular weight determination are described in paragraphs

[0044] -

[0051] of International Publication No. WO2019 / 246069A1, which is incorporated herein by reference (it should be noted that the equation for c in terms of the concentration I at each point in the chromatogram cited in paragraph

[0044] thereof is c = βI, where β is a mass constant and I is the IR5 broadband signal intensity (I) minus the baseline). Unless otherwise specifically mentioned, all molecular weight moments used or mentioned in the present disclosure are determined according to the conventional molecular weight (IR molecular weight) determination method (e.g., as cited in paragraphs

[0044] -

[0045] of the disclosure just mentioned), and it should be noted that for the equation in paragraph

[0044] , a = 0.695 and K = 0.000579(1 - 0.75Wt) are used, where Wt is the weight fraction of the hexane comonomer, and it should also be noted that the comonomer composition is determined by the ratio of the IR5 detector intensities corresponding to the CH2 and CH3 channels, and the channels are calibrated with a series of PE and PP homopolymer / copolymer standard samples, the nominal values of which are pre-determined by NMR or FTIR (providing methyl groups per 1000 total carbons (CH3 / 1000TC)), as indicated in paragraph

[0045] of the international publication just mentioned).

[0104] All numerical values are "about" or "substantially" indicative values, and experimental errors and deviations that would be expected by a person of ordinary skill in the art are taken into account.

[0105] In view of the foregoing description, many changes, modifications, and variations will be apparent to those skilled in the art without departing from the spirit or scope of the present disclosure, and when numerical lower limits and numerical upper limits are listed herein, the ranges from any lower limit to any upper limit are considered.

[0106] The various terms have been defined above. If a term used in a claim is not defined above, it should be given its broadest definition, as the term is known to persons in the relevant field as reflected in at least one printed publication or issued patent. Additionally, all patents, test procedures, and other documents cited in this application are hereby incorporated by reference in their entirety to the extent that this disclosure is consistent therewith and for all jurisdictions permitting such incorporation.

[0107] While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope of the invention is determined by the claims that follow.

Claims

1. A method for devolatilizing a low-viscosity polymer, comprising: providing a reaction mixture comprising a polymer and one or more volatiles, wherein the one or more volatiles comprise one or more unreacted monomers and at least one hydrocarbon solvent; separating the reaction mixture in a first separator into a polymer-rich phase and a polymer-lean phase; separating the polymer-rich phase in a second separator into a vapor hydrocarbon phase and a concentrated polymer phase; removing at least a portion of the volatiles from the concentrated polymer phase in a third separator to provide a devolatilized polymer; and providing a residence time of about 0.2 seconds to 10 seconds in a separator conduit located between the second separator and the third separator.

2. The method of claim 1, wherein the polymer comprises propylene and up to 20 wt% of ethylene and / or one or more monomers having 4 or more carbon atoms.

3. The method of claim 1, wherein when measured at 190 °C and 0.1 s -1 frequency, the polymer has a Brookfield viscosity of 300 cP to 40,000 cP or a zero-shear viscosity of less than 200 Pa-s.

4. The method of claim 1, wherein the polymer has a weight-average molecular weight (Mw) of less than 62,000 g / mol as determined by GPC or a melt flow rate (MFR) of 500 to 40,000 g / 10 min as measured by ASTM D1238.

5. The method of claim 1, wherein the concentrated polymer phase has a volatile concentration of 4 wt% to 15 wt% based on the total weight of the concentrated polymer phase.

6. The method of claim 1, wherein the separator conduit is configured to provide a shear rate of 2,000 to 200,000 1 / s.

7. The method of claim 1, wherein the devolatilized polymer has a volatile concentration of less than 600 ppmw based on the total weight of the concentrated polymer phase.

8. A method for devolatilizing a low-viscosity polymer, comprising: providing a reaction mixture comprising a polymer having a Brookfield viscosity of less than 40,000 cP and a weight-average molecular weight (Mw) of less than 62,000 g / mol as determined by GPC and one or more volatiles, wherein the one or more volatiles comprise one or more unreacted monomers and at least one hydrocarbon solvent; separating the reaction mixture in a first separator into a polymer-rich phase and a polymer-lean phase; separating the polymer-rich phase in a second separator into a vapor hydrocarbon phase and a concentrated polymer phase; removing at least a portion of the volatiles from the concentrated polymer phase in a third separator to provide a devolatilized polymer; and providing a residence time of about 0.2 seconds to 10 seconds in a separator conduit located between the second separator and the third separator.

9. The method of claim 8, wherein the polymer comprises propylene and up to 20 wt% of ethylene and / or one or more monomers having 4 or more carbon atoms.

10. The method of claim 8, wherein the polymer has a Brookfield viscosity of less than 15,000 cP.

11. The method of claim 8, wherein the concentrated polymer phase has a volatile concentration of 4 wt% to 15 wt% based on the total weight of the concentrated polymer phase.

12. The method of claim 8, wherein the separator conduit is configured to provide a shear rate of 2,000 to 200,000 1 / s under the third separator conditions.

13. The method of claim 8, wherein the devolatilized polymer has a volatile concentration of less than 600 ppmw based on the total weight of the concentrated polymer phase.

14. A method for devolatilizing a low-viscosity polymer, comprising: providing a reaction mixture comprising: a polymer having a Brookfield viscosity of less than 40,000 cP, a weight-average molecular weight (Mw) of less than 62,000 g / mol as determined by GPC, and an MFR of 500 - 40,000 g / 10 min (ASTM D1238), and one or more volatiles comprising one or more unreacted monomers and at least one hydrocarbon solvent; separating the reaction mixture into a polymer-rich phase and a polymer-lean phase in a first separator; separating the polymer-rich phase into a vapor hydrocarbon phase and a concentrated polymer phase in a second separator; removing at least a portion of the volatiles from the concentrated polymer phase in a third separator to provide a devolatilized polymer; and providing a residence time of about 0.2 seconds to 10 seconds under the third separator conditions in a separator conduit located between the second separator and the third separator.

15. The method of claim 14, wherein the separator conduit is configured to provide a shear rate of 2,000 to 200,000 1 / s under the third separator conditions.

16. The method of claim 15, wherein the devolatilized polymer has a volatile concentration of less than 600 ppmw based on the total weight of the concentrated polymer phase.

17. The method of claim 15, wherein the polymer is 85 - 99 weight % propylene-derived units and 1 - 15 weight % ethylene-derived units.

18. The method of claim 15, wherein the polymer has a zero shear viscosity of less than 200 Pa-s when measured at 190 °C and 0.1 s -1 frequency.

19. The method of claim 15, wherein the polymer has a weight-average molecular weight (Mw) of less than 46,000 g / mol.

20. A devolatilization system for a low-viscosity polymer, comprising: a first separator that separates a reaction mixture comprising a polymer and one or more volatiles into a polymer-rich phase and a polymer-lean phase, wherein the one or more volatiles comprise one or more unreacted monomers and at least one hydrocarbon solvent, a second separator that separates the polymer-rich phase into a vapor hydrocarbon phase and a concentrated polymer phase; a third separator that removes at least a portion of the volatiles from the concentrated polymer phase; and a separator conduit located between the second separator and the third separator, the separator conduit being configured to provide a residence time of about 0.2 seconds to 10 seconds therein.

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