US20220402188A1 - Polymer recyclate processes and products - Google Patents
Polymer recyclate processes and products Download PDFInfo
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- US20220402188A1 US20220402188A1 US17/845,759 US202217845759A US2022402188A1 US 20220402188 A1 US20220402188 A1 US 20220402188A1 US 202217845759 A US202217845759 A US 202217845759A US 2022402188 A1 US2022402188 A1 US 2022402188A1
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- United States
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- recyclate
- lldpe
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- feedstock
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- Y02W30/62—Plastics recycling; Rubber recycling
Definitions
- the present disclosure relates to the use of extrusion processes to improve the processing characteristics of polyolefin recyclates, either alone or in combination with other polyolefins.
- the invention further relates to compositions produced by such processes.
- Polyolefins including polyethylene and polypropylene, may be used in many applications, including packaging for food and other goods, electronics, automotive components, and a variety of manufactured articles.
- Waste plastic materials may be obtained from a variety of sources, including differential recovery of municipal plastic wastes that are constituted of flexible packaging (cast film, blown film and BOPP film), rigid packaging, blow molded bottles and injection molded containers.
- two main polyolefinic fractions may be obtained, namely polyethylenes (including, HDPE, LDPE, LLDPE) and polypropylenes (including homopolymers, random copolymers, heterophasic copolymers).
- the multicomponent nature of the recycled polyolefins or the polyolefinic fractions may result in low mechanical and optical performances of prepared articles or of polyolefin formulations in which part of a virgin LLDPE is replaced by recycled polymer.
- Unpredictable mechanical and/or optical properties can result from variability of one or more characteristics of the recycled polyolefin including, but not limited to, melt index, high load melt index, melt elasticity, complex viscosity, or combinations thereof.
- the recycled polyolefins or the polyolefinic fractions may contain impurities or contamination by other components.
- the molecular weight, the molecular weight distribution and/or the comonomer content of the recycled polyolefins or of the polyolefinic fractions can limit the range of virgin LLDPEs into which recycled polyolefins can be incorporated.
- Another limitation for the use of recycled polyolefins may be the presence of unpleasant odors coming from volatile organic compounds which may have been absorbed in these polymers during their usage.
- polyethylenes it may be desirable to separate polyethylene waste into portions which are predominately HDPE, predominately MDPE, predominately LDPE, predominately LLDPE, or predominately polypropylene.
- This disclosure provides—in the case of the LLDPE portion—processes to produce polyolefin compositions comprising recycled LLDPE, such polyolefin compositions having a useful combination of properties.
- Such disclosed processes may be highly flexible and could be implemented with commonly used equipment and familiar techniques to produce a wide variety of products.
- the present disclosure relates to methods for processing polyolefin recyclates, in particular linear low density polyethylene (“LLDPE”) recyclates.
- LLDPE linear low density polyethylene
- Such processing includes implementing in an extruder visbreaking conditions to convert a LLDPE recyclate into a visbroken LLDPE recyclate having a reduced weight average molecular weight.
- the LLDPE recyclate is also subjected to devolatilization conditions to convert the LLDPE recyclate into a visbroken LLDPE recyclate having a reduced weight average molecular weight and a reduced volatile organic compounds (“VOC”) content.
- VOC reduced volatile organic compounds
- Visbreaking conditions include thermal visbreaking and/or peroxidation visbreaking.
- Thermal visbreaking includes temperature, pressure, and mechanical shear sufficient to cause polymer chain scission to predominate over polymer chain branching or crosslinking.
- Peroxidation visbreaking may occur when a peroxide as added to the polymer melt in an extruder followed by thermal decomposition of the peroxide to form free radicals, which react with the polymer chain to result in chain scission.
- visbreaking conditions consist of thermal visbreaking at a temperature at least 180° C. above the melting point of the LLDPE in the absence of or substantially in the absence of oxygen.
- Devolatilization conditions can include reduction of VOC in a polyolefin by a portion of an extruder having an intensive mixing arrangement and devolatilization sections to enable removal of VOC at high temperatures. Devolatilization conditions can be further enhanced by injection of a gas into the extruder, distribution of the gas in the polymer melt to scavenge VOC components, and extraction of the gas and scavenged VOC components by venting and/or vacuum.
- the processed LLDPE recyclate can be pelletized as a product at the extruder discharge.
- the processed LLDPE recyclate can be fed to a second extruder to be compounded or blended with a virgin LLDPE.
- the virgin LLDPE can be the polyolefin powder product from a polymerization apparatus, a pelletized polyolefin, or the polyolefin melt, which is the product of a third extruder.
- the virgin LLDPE can have been subjected to a visbreaking process prior to addition to the second reactor.
- virgin LLDPE is fed to a third extruder and the polymer melt form the third extruder is co-fed to the second extruder along with processed LLDPE recyclate melt.
- a composition where the composition is or comprises a polymer blend of from 5 wt. % to 90 wt. % of a LLDPE recyclate and from 10 wt. % to 95 wt. % of a virgin LLDPE, wherein all weight percentages are based on the combined weight of the polymer blend and one or both of the LLDPE recyclate feedstock and the virgin LLDPE are visbroken. Visbreaking can be thermal visbreaking and/or peroxidation visbreaking.
- FIG. 1 is a simplified flow diagram of the process to obtain a processed LLDPE recyclate according to embodiments of the invention
- FIG. 2 is simplified flow diagram of the process to obtain a blend of a processed LLDPE recyclate and a virgin LLDPE using two extruders according to embodiments of the invention
- FIG. 3 is simplified flow diagram of the process to obtain a blend of a processed LLDPE recyclate and a virgin LLDPE using three extruders according to embodiments of the invention
- FIG. 4 is an overlaid graph showing the effects of visbreaking an LLDPE on complex viscosity according to embodiments of the invention.
- FIG. 5 is an overlaid graph showing the effects of visbreaking an LLDPE on molecular weight according to embodiments of the invention.
- Antioxidant agents means compounds that inhibit oxidation, a chemical reaction that can produce free radicals and chain reactions.
- Compounding conditions means temperature, pressure, and shear force conditions implemented in an extruder to provide intimate mixing of two or more polymers and optionally additives to produce a substantially homogeneous polymer product.
- Devolatilization conditions means subjecting a polymer melt in an extruder to injection and withdrawal of a scavenging gas, addition of heat, physical mixing, pressure reduction by venting or applying vacuum, or a combination thereof.
- Devolatilization conditions implemented in an extruder are sufficient to reduce the VOC of a polymer fed to the extruder by a predetermined percentage and/or to a predetermined VOC target for polymer exiting the extruder.
- Devolatilization conditions are directed to reduction of VOC in a polyolefin by a portion of an extruder having an intensive mixing arrangement and devolatilization sections to enable removal of VOC at high temperatures.
- Devolatilization conditions can be further enhanced by injection of a gas into the extruder, distribution of the gas in the polymer melt to scavenge VOC components, and extraction of the gas and scavenged VOC components by venting or vacuum.
- Devolatilized LLDPE recyclate means the product obtained by subjecting an LLDPE recyclate feedstock to devolatilization conditions as described herein.
- Extruder means separate extrusion apparatuses, and in other embodiments, means separate sections within a single extrusion apparatus.
- the first extruder and the second extruder are separate machines.
- the first extruder and the second extruder are separate sections in a single machine.
- the second extruder and the third extruder are separate machines.
- the second extruder and the third extruder are separate sections in a single machine.
- the first extruder, the second extruder, and the third extruder are separate machines.
- the first extruder, the second extruder, and the third extruder are separate sections in a single machine.
- Extruder includes any device or combinations of devices capable of continuously processing one or more polyolefins under visbreaking conditions, compounding conditions, melting conditions, or devolatilization conditions, including, but not limited to, Farrel continuous mixers (FCMTM mixers, available from Farrel Corporation, Ansonia, Conn.).
- FCMTM mixers Farrel continuous mixers
- HDPE as used herein, means ethylene homopolymers and ethylene copolymers produced in a suspension, solution, slurry, or gas phase polymerization process and having a density in the range of 0.940 g/cm 3 to 0.970 g/cm 3 .
- LLDPE recyclate feedstock means LLDPE recyclate after collection and sorting but prior to being subjected to the processes disclosed herein.
- LLC recyclate means post-consumer recycled (“PCR”) LLDPE and/or post-industrial recycled (“PIR”) LLDPE.
- Polyolefin recyclate is derived from an end product that has completed its life cycle as a consumer item and would otherwise be disposed of as waste (e.g., a polyethylene water bottle) or from plastic scrap that is generated as waste from an industrial process.
- Post-consumer polyolefins include polyolefins that have been collected in commercial and residential recycling programs, including flexible packaging (cast film, blown film and BOPP film), rigid packaging, blow molded bottles, and injection molded containers.
- polyethylene recyclate including HDPE, MDPE, LDPE, and LLDPE
- polypropylene recyclate including homopolymers, random copolymers, and heterophasic copolymers.
- Polyethylene recyclate can be further separated to recover a portion having LLDPE as the primary constituent.
- LLDPE recyclate frequently contains other impurities such as PMMA, PC, wood, paper, textile, cellulose, food, and other organic wastes, many of which cause the LLDPE recyclate to have an unpleasant odor before and after typical processing.
- LDPE ethylene homopolymers and ethylene copolymers produced in a high pressure free radical polymerization and having a density in the range of 0.910 g/cm 3 to 0.940 g/cm 3 .
- LLCPE as used herein, means ethylene copolymers produced in a suspension, solution, slurry, or gas phase polymerization process and having a density in the range of 0.910 g/cm 3 to 0.940 g/cm 3 .
- MDPE means ethylene copolymers produced in a suspension, solution, slurry, or gas phase polymerization process and having a density in the range of 0.925 g/cm 3 to 0.940 g/cm 3 .
- Melting conditions means temperature, pressure, and shear force conditions, either alone or in combination with one another, that are required to produce a polymer melt from a feed of polymer pellets or powder.
- Processed LLDPE recyclate means the product obtained by subjecting an LLDPE recyclate feedstock to visbreaking conditions or to visbreaking conditions followed by devolatilization conditions, as described herein.
- “Virgin LLDPEs,” as used herein, are pre-consumer polyolefins.
- Pre-consumer polyolefins are polyolefin products obtained directly or indirectly from petrochemical feedstocks fed to a polymerization apparatus.
- Pre-consumer polyolefins can be subjected to post polymerization processes such as, but not limited to, extrusion, pelletization, visbreaking, and/or other processing completed before the product reaches the end-use consumer.
- virgin LLDPEs have a single heat history.
- virgin LLDPEs have more than one heat history.
- virgin LLDPEs comprise no additives.
- virgin LLDPEs comprise additives.
- Viscobreaking conditions means thermal visbreaking and/or peroxidation visbreaking.
- Thermal visbreaking includes temperature, pressure, and/or mechanical shear sufficient to cause polymer chain scission to predominate of polymer chain branching or crosslinking.
- Peroxidation visbreaking occurs when a peroxide as added to the polymer melt in an extruder followed by thermal decomposition of the peroxide to form free radicals, which react with the polymer chain to result in chain scission.
- a polymer that has been visbroken will have lower number average and weight average molecular weight, a narrower molecular weight distribution, higher melt index, and a higher high load melt index.
- visbreaking conditions consist of thermal visbreaking at a temperature greater than or equal to 300° C., or in the range of from 320° C. to 400° C., in the absence of or substantially in the absence of oxygen.
- “Visbreaking,” as used herein, means treating a polymer thermally and/or chemically to produce a reduction in M n , M w , and MWD (M w /M n ), and an increase in melt index I 2 (ASTM D-1238, 2.16 kg@190° C.) and high load melt index I 21 (ASTM D-1238, 21.6 kg@190° C.) of the LLDPE so treated.
- Applying high temperatures and/or adding radical source such as peroxides to polyolefinic materials results in degradation of the polymer chains and reduction of the average molecular weight of the polymer. In parallel, the molecular weight distribution gets narrower. When intentionally performing such methods for modifying the properties of polymers, these practices are commonly called “visbreaking”.
- Visbroken LLDPE recyclate means the product obtained by subjecting an LLDPE recyclate feedstock to visbreaking conditions as described herein.
- flow diagram 100 includes a visbreaking extruder 110 having a visbreaking zone 115 and an optional devolatilization zone 120 .
- LLDPE recyclate feedstock 125 is added to visbreaking extruder 110 proximate to the inlet end of the extruder.
- the LLDPE recyclate is drawn through the extruder 110 by one or more rotating screw drives in the barrel of the visbreaking extruder 110 .
- the length of the visbreaking extruder 110 is separated into one or more zones.
- Each zone can have one or more of a specified thread pitch on the screw drive, inlets for injection of gas 130 , 135 , vents or vacuum connections for withdrawal of gas 140 , means for addition or withdrawal of heat, inlets for injection of peroxide 145 , and inlets for injection of additives in order to impart preselected process conditions including, but not limited to pressure, temperature, and/or shear force.
- FIG. 1 shows an embodiment with both a visbreaking zone 115 and an optional devolatilization zone 120 .
- Other embodiments can have a visbreaking zone 115 alone without a devolatilization zone.
- Process conditions in the visbreaking extruder 110 can further be controlled by rotation speed of the screw drive.
- Processed LLDPE recyclate 150 is withdrawn proximate to the discharge of the visbreaking extruder 110 for further processing or pelletization.
- LLDPE recyclate feedstock is derived from ethylene homopolymers, copolymers of units derived from ethylene and units derived from one or more of C 3 -C 12 ⁇ -olefins, copolymers of units derived from ethylene and units derived from one or more of alpha mono-olefins.
- C 3 -C 12 ⁇ -olefins include, but are not limited to, substituted or unsubstituted C 3 to C 12 alpha olefins such as propylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecane, and isomers thereof.
- LLDPE recyclate feedstock can be derived as a portion of post-consumer recycled polyolefin and/or post-industrial recycled polyolefin that is predominately comprised of LLDPE recyclate, wherein “predominately” means greater than or equal to 80 wt %, greater than or equal to 85 wt %, greater than or equal to 90 wt %, or greater than or equal to 95 wt %, based on the total weight of the LLDPE recyclate feedstock.
- Such ethylene homopolymers and/or copolymers can be produced in a suspension, solution, slurry, or gas phase process, using known equipment and reaction conditions.
- polymerization temperatures range from about 0° C. to about 300° C. at atmospheric, subatmospheric, or superatmospheric pressures.
- Liquid phase polymerization systems can utilize subatmospheric or superatmospheric pressures and temperatures in the range of about 40° C. to about 300° C.
- An exemplary liquid phase polymerization system is described in U.S. Pat. No. 3,324,095, the disclosure of which is fully incorporated by reference herein.
- Liquid phase polymerization systems generally comprise a reactor to which olefin monomer and catalyst composition are added, and which contains a liquid reaction medium for dissolving or suspending the polyolefin.
- the liquid reaction medium may consist of the bulk liquid monomer or an inert liquid hydrocarbon that is nonreactive under the polymerization conditions employed.
- an inert liquid hydrocarbon need not function as a solvent for the catalyst composition or the polymer obtained by the process, it usually serves as solvent for the monomers employed in the polymerization.
- the inert liquid hydrocarbons suitable for this purpose are isopentane, hexane, cyclohexane, heptane, benzene, toluene, and the like. Reactive contact between the olefin monomer and the catalyst composition should be maintained by constant stirring or agitation.
- the reaction medium containing the olefin polymer product and unreacted olefin monomer is withdrawn from the reactor continuously.
- the olefin polymer product is separated, and the unreacted olefin monomer and liquid reaction medium are recycled into the reactor.
- Gas phase polymerization systems can utilize superatmospheric pressures in the range of from 1 psig (6.9 kPag) to 1,000 psig (6.9 MPag), 50 psig (344 kPag) to 400 psig (2.8 MPag), or 100 psig (689 kPag) to 300 psig (2.1 MPag), and temperatures in the range of from 30° C. to 130° C. or 65° C. to 110° C.
- Gas phase polymerization systems can be stirred or fluidized bed systems.
- a gas phase, fluidized bed process is conducted by passing a stream containing one or more olefin monomers continuously through a fluidized bed reactor under reaction conditions and in the presence of catalyst composition at a velocity sufficient to maintain a bed of solid particles in a suspended condition.
- a stream containing unreacted monomer is withdrawn from the reactor continuously, compressed, cooled, optionally partially or fully condensed, and recycled into the reactor.
- Product is withdrawn from the reactor and make-up monomer is added to the recycle stream.
- any gas inert to the catalyst composition and reactants may also be present in the gas stream.
- a Ziegler-Natta (ZN)catalyst is used.
- ZN Ziegler-Natta
- Such catalysts are based on a Group IVB transition metal compound and an organoaluminum compound (co-catalyst).
- Such transition metals include, but not limited to, Ti, Zr, and Hf
- Nonlimiting examples of ZN catalyst systems include TiCl 4 +Et 3 Al and TiCl 3 +AlEt 2 Cl.
- Such LLDPE homopolymers and/or copolymers have some long-chain branching and a density in the range of from 0.910 g/cm 3 to 0.940 g/cm 3 .
- LLDPE recyclate feedstock derived from LLDPE as described above, can be characterized by having:
- the LLDPE recyclate feedstock can be further characterized by having one or more of
- LLDPE recyclate feedstock is fed to a first extruder and is subjected to visbreaking conditions and optionally devolatilization conditions.
- Visbreaking conditions are implemented in the visbreaking zone of the first extruder and are tailored for LLDPE.
- visbreaking conditions means thermal visbreaking and/or peroxidation visbreaking.
- visbreaking conditions consist of thermal visbreaking, wherein the temperature in the visbreaking zone is greater than or equal to 300° C., where it is believed that chain scission reactions exceed long-chain branching and/or crosslinking reactions.
- temperatures in the visbreaking zone can be in the range of from 320° C. to 500° C., from 340° C. to 480° C., or from 360° C. to 460° C.
- instrumentation at the first extruder discharge monitors rheology directly or indirectly (I 2 , I 21 , viscosity, melt elasticity, complex viscosity ratio, or the like) to measure and assist in control of visbreaking.
- the antioxidant addition point is at a location on the first extruder after a substantial portion of the visbreaking reaction has taken place.
- visbreaking conditions consist of thermal visbreaking the absence of or substantially in the absence of oxygen, wherein substantial absence of oxygen means less than or equal to 1.0 wt %, less than or equal to 0.10 wt %, or less than or equal to 0.01 wt %, based on the total weight of polymer in the extruder.
- the visbreaking extruder comprises one or more melt filters.
- Devolatilization conditions are optionally implemented in the first extruder and are directed to reduction of VOC in the LLDPE recyclate feedstock by a portion of an extruder having an intensive mixing arrangement and devolatilization sections to enable removal of VOC at high temperatures.
- Devolatilization conditions can be further enhanced by: injection of a scavenging gas, such as, but not limited to, nitrogen, carbon-dioxide, water, or combinations thereof, into the extruder; distribution of the gas in the polymer melt to scavenge VOC components; and extraction of the gas and scavenged VOC components by venting and/or vacuum.
- a scavenging gas such as, but not limited to, nitrogen, carbon-dioxide, water, or combinations thereof
- a processed LLDPE recyclate is withdrawn from the discharge of the visbreaking extruder, wherein “processed” means that the LLDPE recyclate feedstock was subjected to visbreaking conditions or visbreaking conditions followed by devolatilization conditions.
- Processed LLDPE recyclate as described above, can be characterized by having:
- the processed LLDPE recyclate can be further characterized by having one or more of:
- flow diagram 200 includes a visbreaking extruder 210 and a compounding extruder 255 .
- Embodiments of the present invention as shown in FIG. 2 include a visbreaking extruder 210 having a visbreaking zone 215 and a devolatilization zone 220 .
- LLDPE recyclate feedstock 225 is added to visbreaking extruder 210 proximate to the inlet end of the extruder.
- the LLDPE recyclate feedstock 225 is drawn through the visbreaking extruder 210 by one or more rotating screw drives in the barrel of the visbreaking extruder 210 .
- the length of the visbreaking extruder 210 is separated into one or more zones.
- Each zone can have one or more of a specified thread pitch on the screw drive, inlets for injection of gas 230 , 235 , vents or vacuum connections for withdrawal of gas 240 , means for addition or withdrawal of heat, inlets for injection of peroxide 245 , and inlets for injection of additives in order to impart preselected process conditions including, but not limited to pressure, temperature, and shear force.
- FIG. 2 shows an embodiment with both a visbreaking zone 215 and a devolatilization zone 220 .
- Other embodiments can have either a visbreaking zone 215 or a devolatilization zone 220 independently without the other.
- Process conditions in the visbreaking extruder 210 can further be controlled by rotation speed of the screw drive.
- Processed LLDPE recyclate 250 is withdrawn proximate to the discharge of the visbreaking extruder 210 for further processing.
- Embodiments of FIG. 2 include a second extruder 255 , having a compounding zone 260 .
- Processed LLDPE recyclate 250 is added to compounding extruder 255 as a first blend component proximate to the inlet end of the extruder along with a polyolefin blend component 252 and subjected to compounding conditions.
- the polyolefin blend component 252 comprises a virgin polyolefin, a polyolefin recyclate feedstock, a processed polyolefin recyclate, or a combination thereof.
- the virgin polyolefin comprises a virgin HDPE, a virgin LLDPE, a virgin HDPE, a virgin MDPE, a virgin polypropylene, or a combination thereof.
- the polyolefin recyclate feedstock comprises a LDPE recyclate feedstock, a LLDPE recyclate feedstock, a HDPE recyclate feedstock, a MDPE recyclate feedstock, a polypropylene recyclate feedstock, or a combination thereof.
- the processed polyolefin recyclate comprises a processed LDPE recyclate, a second processed LLDPE recyclate, a processed HDPE recyclate, a processed MDPE recyclate, a processed polypropylene recyclate, or a combination thereof.
- a polyolefin blend component comprises a virgin LLDPE, a LLDPE recyclate feedstock, a processed LLDPE recyclate, or a combination thereof.
- the mixture of LLDPE recyclate 250 and polyolefin blend component 252 is drawn through the compounding extruder 255 by one or more rotating screw drives in the barrel of the extruder 255 .
- One or more additional inlets proximate to the inlet end of the extruder provide for the addition of antioxidant agent 265 and/or other components 270 .
- the length of the compounding extruder 255 can be separated into one or more zones. Each zone can have one or more of a specified thread pitch on the screw drive, means for addition or withdrawal of heat, inlets for injection of additives. and vents or vacuum connections for withdrawal of gas 275 , in order to impart preselected process conditions including, but not limited to pressure, temperature, and shear force.
- a blend 280 of the processed LLDPE recyclate 250 and the polyolefin blend component 252 is withdrawn proximate to the discharge of the compounding extruder 255 for further processing or pelletization.
- the polyolefin blend component can be a polyolefin powder product from a polymerization apparatus, a pelletized polyolefin, or the polyolefin melt, which is the product withdrawn from a third extruder.
- the polymerization apparatus comprises two, three, or more polymerization reactors and/or two, three, or more polymerization zones within a polymerization reactor. More specific polymerization apparatus embodiments include, but are not limited to, two or three gas phase fluidized-bed reactors in series, two or three slurry phase reactors in series, and a gas phase fluidized-bed reactor in series with a multizone circulation reactor.
- the amount of the polyolefin blend component, which itself can comprise two or more polymers is determined based on the logarithmic mixing rule, wherein blend components satisfy the following equation:
- a first blend component is a processed LLDPE recyclate produced from a visbreaking extruder.
- a second blend component comprises a virgin polyolefin, a polyolefin recyclate feedstock, a processed polyolefin recyclate, or a combination thereof.
- the virgin polyolefin comprises a virgin LDPE, a virgin LLDPE, a virgin HDPE, a virgin polypropylene, or a combination thereof.
- the polyolefin recyclate feedstock comprises a LDPE recyclate feedstock, a LLDPE recyclate feedstock, a HDPE recyclate feedstock, a polypropylene recyclate feedstock, or a combination thereof.
- the processed polyolefin recyclate comprises a processed LDPE recyclate, a second processed LLDPE recyclate, a processed HDPE recyclate, a processed polypropylene recyclate, or a combination thereof.
- a polyolefin blend component comprises a virgin LLDPE, a LLDPE recyclate feedstock, a processed LLDPE recyclate, or a combination thereof.
- the first LLDPE recyclate will have at least one parameter that distinguishes it from the second processed LLDPE recyclate.
- virgin LLDPE is from ethylene homopolymers, copolymers of units derived from ethylene and units derived from one or more of C 3 -C 12 ⁇ -olefins, copolymers of units derived from ethylene and units derived from one or more of alpha mono-olefins.
- C 3 -C 12 ⁇ -olefins include, but are not limited to, substituted or unsubstituted C 3 to C 12 alpha olefins such as propylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecane, and isomers thereof.
- comonomers can be present in amounts up to 20 wt %, 15 wt %, 10 wt %, or 5 wt %.
- Such ethylene homopolymers and/or copolymers can be produced in a suspension, solution, slurry, or gas phase process, using known equipment and reaction conditions.
- polymerization temperatures range from about 0° C. to about 300° C. at atmospheric, subatmospheric, or superatmospheric pressures.
- Liquid phase polymerization systems can utilize subatmospheric or superatmospheric pressures and temperatures in the range of about 40° C. to about 300° C.
- An exemplary liquid phase polymerization system is described in U.S. Pat. No. 3,324,095, the disclosure of which is fully incorporated by reference herein.
- Liquid phase polymerization systems generally comprise a reactor to which olefin monomer and catalyst composition are added, and which contains a liquid reaction medium for dissolving or suspending the polyolefin.
- the liquid reaction medium may consist of the bulk liquid monomer or an inert liquid hydrocarbon that is nonreactive under the polymerization conditions employed.
- an inert liquid hydrocarbon need not function as a solvent for the catalyst composition or the polymer obtained by the process, it usually serves as solvent for the monomers employed in the polymerization.
- the inert liquid hydrocarbons suitable for this purpose are isopentane, hexane, cyclohexane, heptane, benzene, toluene, and the like. Reactive contact between the olefin monomer and the catalyst composition should be maintained by constant stirring or agitation.
- the reaction medium containing the olefin polymer product and unreacted olefin monomer is withdrawn from the reactor continuously.
- the olefin polymer product is separated, and the unreacted olefin monomer and liquid reaction medium are recycled into the reactor.
- Gas phase polymerization systems can utilize superatmospheric pressures in the range of from 1 psig (6.9 kPag) to 1,000 psig (6.9 MPag), 50 psig (344 kPag) to 400 psig (2.8 MPag), or 100 psig (689 kPag) to 300 psig (2.1 MPag), and temperatures in the range of from 30° C. to 130° C. or 65° C. to 110° C.
- Gas phase polymerization systems can be stirred or fluidized bed systems.
- a gas phase, fluidized bed process is conducted by passing a stream containing one or more olefin monomers continuously through a fluidized bed reactor under reaction conditions and in the presence of catalyst composition at a velocity sufficient to maintain a bed of solid particles in a suspended condition.
- a stream containing unreacted monomer is withdrawn from the reactor continuously, compressed, cooled, optionally partially or fully condensed, and recycled into the reactor.
- Product is withdrawn from the reactor and make-up monomer is added to the recycle stream.
- any gas inert to the catalyst composition and reactants may also be present in the gas stream.
- a Ziegler-Natta (ZN)catalyst is used.
- ZN Ziegler-Natta
- Such catalysts are based on a Group IVB transition metal compound and an organoaluminum compound (co-catalyst).
- Such transition metals include, but not limited to, Ti, Zr, and Hf
- Nonlimiting examples of ZN catalyst systems include TiCl 4 +Et 3 Al and TiCl 3 +AlEt 2 Cl.
- Such LLDPE homopolymers and/or copolymers have some long-chain branching and a density in the range of from 0.910 g/cm 3 to 0.940 g/cm 3 .
- LLDPE recyclate feedstock is derived from ethylene homopolymers, copolymers of units derived from ethylene and units derived from one or more of C 3 -C 12 ⁇ -olefins, copolymers of units derived from ethylene and units derived from one or more of alpha mono-olefins.
- C 3 -C 12 ⁇ -olefins include, but are not limited to, substituted or unsubstituted C 3 to C 12 alpha olefins such as propylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecane, and isomers thereof.
- LLDPE recyclate feedstock can be derived as a portion of post-consumer recycled polyolefin and/or post-industrial recycled polyolefin that is predominately comprised of LLDPE recyclate, wherein “predominately” means wherein “predominately” means greater than or equal to 80 wt %, greater than or equal to 85 wt %, greater than or equal to 90 wt %, or greater than or equal to 95 wt %, based on the total weight of the LLDPE recyclate feedstock.
- Such ethylene homopolymers and/or copolymers can be produced in a suspension, solution, slurry, or gas phase process, using known equipment and reaction conditions.
- polymerization temperatures range from about 0° C. to about 300° C. at atmospheric, subatmospheric, or superatmospheric pressures.
- Liquid phase polymerization systems can utilize subatmospheric or superatmospheric pressures and temperatures in the range of about 40° C. to about 300° C.
- An exemplary liquid phase polymerization system is described in U.S. Pat. No. 3,324,095, the disclosure of which is fully incorporated by reference herein.
- Liquid phase polymerization systems generally comprise a reactor to which olefin monomer and catalyst composition are added, and which contains a liquid reaction medium for dissolving or suspending the polyolefin.
- the liquid reaction medium may consist of the bulk liquid monomer or an inert liquid hydrocarbon that is nonreactive under the polymerization conditions employed.
- an inert liquid hydrocarbon need not function as a solvent for the catalyst composition or the polymer obtained by the process, it usually serves as solvent for the monomers employed in the polymerization.
- the inert liquid hydrocarbons suitable for this purpose are isopentane, hexane, cyclohexane, heptane, benzene, toluene, and the like. Reactive contact between the olefin monomer and the catalyst composition should be maintained by constant stirring or agitation.
- the reaction medium containing the olefin polymer product and unreacted olefin monomer is withdrawn from the reactor continuously.
- the olefin polymer product is separated, and the unreacted olefin monomer and liquid reaction medium are recycled into the reactor.
- Gas phase polymerization systems can utilize superatmospheric pressures in the range of from 1 psig (6.9 kPag) to 1,000 psig (6.9 MPag), 50 psig (344 kPag) to 400 psig (2.8 MPag), or 100 psig (689 kPag) to 300 psig (2.1 MPag), and temperatures in the range of from 30° C. to 130° C. or 65° C. to 110° C.
- Gas phase polymerization systems can be stirred or fluidized bed systems.
- a gas phase, fluidized bed process is conducted by passing a stream containing one or more olefin monomers continuously through a fluidized bed reactor under reaction conditions and in the presence of catalyst composition at a velocity sufficient to maintain a bed of solid particles in a suspended condition.
- a stream containing unreacted monomer is withdrawn from the reactor continuously, compressed, cooled, optionally partially or fully condensed, and recycled into the reactor.
- Product is withdrawn from the reactor and make-up monomer is added to the recycle stream.
- any gas inert to the catalyst composition and reactants may also be present in the gas stream.
- a Ziegler-Natta (ZN)catalyst is used.
- ZN Ziegler-Natta
- Such catalysts are based on a Group IVB transition metal compound and an organoaluminum compound (co-catalyst).
- Such transition metals include, but not limited to, Ti, Zr, and Hf
- Nonlimiting examples of ZN catalyst systems include TiCl 4 +Et 3 Al and TiCl 3 +AlEt 2 Cl.
- Such LLDPE homopolymers and/or copolymers have some long-chain branching and a density in the range of from 0.910 g/cm 3 to 0.940 g/cm 3 .
- LLDPE recyclate feedstock derived from LLDPE as described above, can be characterized by having:
- the LLDPE recyclate feedstock can be further characterized by having one or more of
- a processed LLDPE recyclate is withdrawn from the discharge of the visbreaking extruder, wherein “processed” means that the LLDPE recyclate feedstock was subjected to visbreaking conditions or visbreaking conditions followed by devolatilization conditions.
- Processed LLDPE recyclate as described above, can be characterized by having:
- the processed LLDPE recyclate can be further characterized by having one or more of:
- Processed LLDPE recyclate and a polyolefin blend component are fed to a second extruder or mixer wherein the blend is subjected to compounding conditions.
- Compounding conditions are implemented in the compounding zone of the second extruder or mixer and are tailored for mixtures of specific polyolefins and optionally additives.
- Temperature, pressure, and shear force conditions are implemented in the second extruder or mixer sufficient to provide intimate mixing of the processed LLDPE recyclate and the virgin LLDPE and optionally additives to produce a substantially homogeneous polymer blend of the processed LLDPE recyclate and the virgin LLDPE.
- compounding conditions comprise a temperature in the compounding zone of less than or equal to 300° C., less than or equal to 250° C. or less than or equal to 200° C. In some embodiments, temperatures in the compounding zone can be in the range of from 125° C. to 195° C., from 130° C. to 180° C., or from 135° C. to 165° C.
- the blend comprises from 5 wt. % to 90 wt. %, 10 wt. % to 80 wt. %, 15 wt. % to 70 wt. %, 20 wt. % to 60 wt. %, or 25 wt. % to 50 wt. %, of a processed LLDPE recyclate and from 10 wt. % to 95 wt. %, 20 wt. % to 90 wt. %, 30 wt. % to 85 wt. %, 40 wt. % to 80 wt. %, or 50 wt. % to 75 wt.
- the virgin LLDPE is visbroken.
- Such visbreaking of virgin LLDPE can be thermal visbreaking and/or peroxidation visbreaking.
- such visbreaking conditions for a virgin LLDPE consist of thermal visbreaking at a temperature above the melting point of the LLDPE, greater than or equal to 300° C., or in the range of from 320° C. to 400° C., in the absence of or substantially in the absence of oxygen.
- the blends of processed LLDPE recyclate and a polyolefin blend component in combination with or independently of the blend ratios in the preceding paragraph, comprise a bimodal polymer, wherein the processed LLDPE recyclate product has a weight average molecular weight (“M w3 ”), the polyolefin blend component has a weight average molecular weight (“M w4 ”); and M w3 /M w4 is either less than or equal to 0.9, 0.8, 0.7, 0.6, or 0.5, or alternatively is greater than or equal to 1.1, 1.25, 1.5, 1.75, or 2.0.
- M w3 weight average molecular weight
- M w4 weight average molecular weight
- M w3 /M w4 is either less than or equal to 0.9, 0.8, 0.7, 0.6, or 0.5, or alternatively is greater than or equal to 1.1, 1.25, 1.5, 1.75, or 2.0.
- flow diagram 300 includes a visbreaking extruder 310 , a melting extruder 357 , and a compounding extruder 355 .
- Embodiments of the present invention as shown in FIG. 3 include a visbreaking extruder 310 having a visbreaking zone 315 and a devolatilization zone 320 .
- LLDPE recyclate feedstock 325 is added to visbreaking extruder 310 proximate to the inlet end of the extruder.
- the LLDPE recyclate feedstock 325 is drawn through the visbreaking extruder 310 by one or more rotating screw drives in the barrel of the visbreaking extruder 310 .
- the length of the visbreaking extruder 310 is separated into one or more zones.
- Each zone can have one or more of a specified thread pitch on the screw drive, inlets for injection of gas 330 , 335 , vents or vacuum connections for withdrawal of gas 340 , means for addition or withdrawal of heat, inlets for injection of peroxide 345 , and inlets for injection of additives in order to impart preselected process conditions including, but not limited to pressure, temperature, and shear force.
- FIG. 3 shows an embodiment with both a visbreaking zone 315 and a devolatilization zone 320 .
- Other embodiments can have either a visbreaking zone 315 or a devolatilization zone 320 independently without the other.
- Process conditions in the visbreaking extruder 310 can further be controlled by rotation speed of the screw drive.
- Processed LLDPE recyclate 350 is withdrawn proximate to the discharge of the visbreaking extruder 310 for further processing.
- Embodiments of FIG. 3 include a second extruder 355 having a compounding zone 360 and a third extruder 357 having a melting zone 362 .
- a third blend component 383 is added to melting extruder 357 proximate to the inlet end of the extruder optionally along with antioxidant agent 365 and other components 370 .
- the polyolefin blend component 352 comprises a virgin polyolefin, a polyolefin recyclate feedstock, a processed polyolefin recyclate, or a combination thereof.
- the virgin polyolefin comprises a virgin LDPE, a virgin LLDPE, a virgin HDPE, a virgin MDPE, a virgin polypropylene, or a combination thereof.
- the polyolefin recyclate feedstock comprises a LDPE recyclate feedstock, a LLDPE recyclate feedstock, a HDPE recyclate feedstock, a MDPE recyclate feedstock, a polypropylene recyclate feedstock, or a combination thereof.
- the processed polyolefin recyclate comprises a processed LDPE recyclate, a second processed LLDPE recyclate, a processed HDPE recyclate, a processed MDPE recyclate, a processed polypropylene recyclate, or a combination thereof.
- a polyolefin blend component comprises a virgin LLDPE, a LLDPE recyclate feedstock, a processed LLDPE recyclate, or a combination thereof.
- the mixture of third blend component 352 and optional antioxidant 365 and/or other components 370 is drawn through the melting extruder 357 by one or more rotating screw drives in the barrel of the melting extruder 357 .
- the length of the melting extruder 357 can be separated into one or more zones. Each zone can have one or more of a specified thread pitch on the screw drive, means for addition or withdrawal of heat, inlets for injection of additives, and vents or vacuum connections for withdrawal of gas, in order to impart preselected process conditions including, but not limited to, pressure, temperature, and shear force.
- a melt of the polyolefin blend component 352 is withdrawn proximate to the discharge of the melting extruder 357 for further processing or pelletization.
- Processed LLDPE recyclate 350 is added to compounding extruder 355 proximate to the inlet end of the extruder along with the melt of the polyolefin blend component 352 .
- the mixture of processed LLDPE recyclate 350 and polyolefin blend component 352 is drawn through the compounding extruder 355 by one or more rotating screw drives in the barrel of the compounding extruder 355 and the mixture is subjected to compounding conditions.
- the length of the compounding extruder 355 can be separated into one or more zones.
- Each zone can have one or more of a specified thread pitch on the screw drive, means for addition or withdrawal of heat, inlets for injection of additives, and vents and/or vacuum connections for withdrawal of gas 375 , in order to impart preselected process conditions including, but not limited to pressure, temperature, and shear force.
- a blend 380 of the processed LLDPE recyclate 350 and the polyolefin blend component 352 melt is withdrawn proximate to the discharge of the compounding extruder 355 for further processing or pelletization.
- the polyolefin blend component can be a polyolefin powder product from a polymerization apparatus, a pelletized polyolefin, or the polyolefin melt, which is the product withdrawn from a third extruder.
- the polymerization apparatus comprises two, three, or more polymerization reactors and/or two, three, or more polymerization zones within a polymerization reactor. More specific polymerization apparatus embodiments include, but are not limited to, two or three gas phase fluidized-bed reactors in series, two or three slurry phase reactors in series, and a gas phase fluidized-bed reactor in series with a multizone circulation reactor.
- the amount of the polyolefin blend component, which itself can comprise two or more polymers is determined based on the logarithmic mixing rule, wherein blend components satisfy the following equation:
- a first blend component is a processed LLDPE recyclate produced from at from a visbreaking extruder.
- a second blend component comprises a virgin polyolefin, a polyolefin recyclate feedstock, a processed polyolefin recyclate, or a combination thereof.
- the virgin polyolefin comprises a virgin LDPE, a virgin LLDPE, a virgin HDPE, a virgin MDPE, a virgin polypropylene, or a combination thereof.
- the polyolefin recyclate feedstock comprises a LDPE recyclate feedstock, a LLDPE recyclate feedstock, a HDPE recyclate feedstock, a MDPE recyclate feedstock, a polypropylene recyclate feedstock, or a combination thereof.
- the processed polyolefin recyclate comprises a processed LDPE recyclate, a second processed LLDPE recyclate, a processed HDPE recyclate, a processed MDPE recyclate, a processed polypropylene recyclate, or a combination thereof.
- the second blend component comprises a virgin LLDPE, a LLDPE recyclate feedstock, a processed LLDPE recyclate, or a combination thereof.
- the processed LLDPE recyclate is blended with another processed LLDPE recyclate, the first LLDPE recyclate will have at least one parameter that distinguishes it from the second processed LLDPE recyclate.
- virgin LLDPE is from ethylene homopolymers, copolymers of units derived from ethylene and units derived from one or more of C 3 -C 12 ⁇ -olefins, copolymers of units derived from ethylene and units derived from one or more of alpha mono-olefins.
- C 3 -C 12 ⁇ -olefins include, but are not limited to, substituted or unsubstituted C 3 to C 12 alpha olefins such as propylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecane, and isomers thereof.
- comonomers can be present in amounts up to 20 wt %, 15 wt %, 10 wt %, or 5 wt %.
- Such ethylene homopolymers and/or copolymers can be produced in a suspension, solution, slurry, or gas phase process, using known equipment and reaction conditions.
- polymerization temperatures range from about 0° C. to about 300° C. at atmospheric, subatmospheric, or superatmospheric pressures.
- Liquid phase polymerization systems can utilize subatmospheric or superatmospheric pressures and temperatures in the range of about 40° C. to about 300° C.
- An exemplary liquid phase polymerization system is described in U.S. Pat. No. 3,324,095, the disclosure of which is fully incorporated by reference herein.
- Liquid phase polymerization systems generally comprise a reactor to which olefin monomer and catalyst composition are added, and which contains a liquid reaction medium for dissolving or suspending the polyolefin.
- the liquid reaction medium may consist of the bulk liquid monomer or an inert liquid hydrocarbon that is nonreactive under the polymerization conditions employed.
- an inert liquid hydrocarbon need not function as a solvent for the catalyst composition or the polymer obtained by the process, it usually serves as solvent for the monomers employed in the polymerization.
- the inert liquid hydrocarbons suitable for this purpose are isopentane, hexane, cyclohexane, heptane, benzene, toluene, and the like. Reactive contact between the olefin monomer and the catalyst composition should be maintained by constant stirring or agitation.
- the reaction medium containing the olefin polymer product and unreacted olefin monomer is withdrawn from the reactor continuously.
- the olefin polymer product is separated, and the unreacted olefin monomer and liquid reaction medium are recycled into the reactor.
- Gas phase polymerization systems can utilize superatmospheric pressures in the range of from 1 psig (6.9 kPag) to 1,000 psig (6.9 MPag), 50 psig (344 kPag) to 400 psig (2.8 MPag), or 100 psig (689 kPag) to 300 psig (2.1 MPag), and temperatures in the range of from 30° C. to 130° C. or 65° C. to 110° C.
- Gas phase polymerization systems can be stirred or fluidized bed systems.
- a gas phase, fluidized bed process is conducted by passing a stream containing one or more olefin monomers continuously through a fluidized bed reactor under reaction conditions and in the presence of catalyst composition at a velocity sufficient to maintain a bed of solid particles in a suspended condition.
- a stream containing unreacted monomer is withdrawn from the reactor continuously, compressed, cooled, optionally partially or fully condensed, and recycled into the reactor.
- Product is withdrawn from the reactor and make-up monomer is added to the recycle stream.
- any gas inert to the catalyst composition and reactants may also be present in the gas stream.
- a Ziegler-Natta (ZN)catalyst is used.
- ZN Ziegler-Natta
- Such catalysts are based on a Group IVB transition metal compound and an organoaluminum compound (co-catalyst).
- Such transition metals include, but not limited to, Ti, Zr, and Hf
- Nonlimiting examples of ZN catalyst systems include TiCl 4 +Et 3 Al and TiCl 3 +AlEt 2 Cl.
- Such LLDPE homopolymers and/or copolymers have some long-chain branching and a density in the range of from 0.910 g/cm 3 to 0.940 g/cm 3 .
- LLDPE recyclate feedstock is derived from ethylene homopolymers, copolymers of units derived from ethylene and units derived from one or more of C 3 -C 12 ⁇ -olefins, copolymers of units derived from ethylene and units derived from one or more of alpha mono-olefins.
- C 3 -C 12 ⁇ -olefins include, but are not limited to, substituted or unsubstituted C 3 to C 12 alpha olefins such as propylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecane, and isomers thereof.
- LLDPE recyclate feedstock can be derived as a portion of post-consumer recycled polyolefin and/or post-industrial recycled polyolefin that is predominately comprised of LLDPE recyclate, wherein “predominately” means greater than or equal to 80 wt %, greater than or equal to 85 wt %, greater than or equal to 90 wt %, or greater than or equal to 95 wt %, based on the total weight of the LLDPE recyclate feedstock.
- Such ethylene homopolymers and/or copolymers can be produced in a suspension, solution, slurry, or gas phase process, using known equipment and reaction conditions.
- polymerization temperatures range from about 0° C. to about 300° C. at atmospheric, subatmospheric, or superatmospheric pressures.
- Liquid phase polymerization systems can utilize subatmospheric or superatmospheric pressures and temperatures in the range of about 40° C. to about 300° C.
- An exemplary liquid phase polymerization system is described in U.S. Pat. No. 3,324,095, the disclosure of which is fully incorporated by reference herein.
- Liquid phase polymerization systems generally comprise a reactor to which olefin monomer and catalyst composition are added, and which contains a liquid reaction medium for dissolving or suspending the polyolefin.
- the liquid reaction medium may consist of the bulk liquid monomer or an inert liquid hydrocarbon that is nonreactive under the polymerization conditions employed.
- an inert liquid hydrocarbon need not function as a solvent for the catalyst composition or the polymer obtained by the process, it usually serves as solvent for the monomers employed in the polymerization.
- the inert liquid hydrocarbons suitable for this purpose are isopentane, hexane, cyclohexane, heptane, benzene, toluene, and the like. Reactive contact between the olefin monomer and the catalyst composition should be maintained by constant stirring or agitation.
- the reaction medium containing the olefin polymer product and unreacted olefin monomer is withdrawn from the reactor continuously.
- the olefin polymer product is separated, and the unreacted olefin monomer and liquid reaction medium are recycled into the reactor.
- Gas phase polymerization systems can utilize superatmospheric pressures in the range of from 1 psig (6.9 kPag) to 1,000 psig (6.9 MPag), 50 psig (344 kPag) to 400 psig (2.8 MPag), or 100 psig (689 kPag) to 300 psig (2.1 MPag), and temperatures in the range of from 30° C. to 130° C. or 65° C. to 110° C.
- Gas phase polymerization systems can be stirred or fluidized bed systems.
- a gas phase, fluidized bed process is conducted by passing a stream containing one or more olefin monomers continuously through a fluidized bed reactor under reaction conditions and in the presence of catalyst composition at a velocity sufficient to maintain a bed of solid particles in a suspended condition.
- a stream containing unreacted monomer is withdrawn from the reactor continuously, compressed, cooled, optionally partially or fully condensed, and recycled into the reactor.
- Product is withdrawn from the reactor and make-up monomer is added to the recycle stream.
- any gas inert to the catalyst composition and reactants may also be present in the gas stream.
- a Ziegler-Natta (ZN)catalyst is used.
- ZN Ziegler-Natta
- Such catalysts are based on a Group IVB transition metal compound and an organoaluminum compound (co-catalyst).
- Such transition metals include, but not limited to, Ti, Zr, and Hf
- Nonlimiting examples of ZN catalyst systems include TiCl 4 +Et 3 Al and TiCl 3 +AlEt 2 Cl.
- Such LLDPE homopolymers and/or copolymers have some long-chain branching and a density in the range of from 0.910 g/cm 3 to 0.940 g/cm 3 .
- LLDPE recyclate feedstock derived from LLDPE as described above, can be characterized by having:
- the LLDPE recyclate feedstock can be further characterized by having one or more of:
- a processed LLDPE recyclate is withdrawn from the discharge of the visbreaking extruder, wherein “processed” means that the LLDPE recyclate feedstock was subjected to visbreaking conditions or visbreaking conditions followed by devolatilization conditions.
- Processed LLDPE recyclate as described above, can be characterized by having:
- the processed LLDPE recyclate can be further characterized by having one or more of:
- the polyolefin blend component and optional antioxidants and/or other components are fed to a third extruder or mixer wherein the blend is subjected to melting conditions.
- Melting conditions are implemented in the meting zone of the third extruder or mixer and are tailored for mixtures of specific polyolefins and optionally additives.
- Temperature, pressure, and shear force conditions are implemented in the second extruder or mixer sufficient to provide intimate mixing of the processed LLDPE recyclate and the virgin LLDPE and optionally additives to produce a substantially homogeneous polymer blend of the processed LLDPE recyclate and the virgin LLDPE.
- melting conditions comprise a temperature in the melting zone in the range of from 130° C. to 250° C. or from 150° C. to 230° C.
- Processed LLDPE recyclate and a polyolefin blend component are fed to a second extruder or mixer wherein the blend is subjected to compounding conditions.
- Compounding conditions are implemented in the compounding zone of the second extruder or mixer and are tailored for mixtures of specific polyolefins and optionally additives.
- Temperature, pressure, and shear force conditions are implemented in the second extruder or mixer sufficient to provide intimate mixing of the processed LLDPE recyclate and the virgin LLDPE and optionally additives to produce a substantially homogeneous polymer blend of the processed LLDPE recyclate and the virgin LLDPE.
- compounding conditions comprise a temperature in the compounding zone of less than or equal to 300° C., less than or equal to 250° C. or less than or equal to 200° C. In some embodiments, temperatures in the compounding zone can be in the range of from 125° C. to 195° C., from 130° C. to 180° C., or from 135° C. to 165° C.
- the blend comprises from 5 wt. % to 90 wt. %, 10 wt. % to 80 wt. %, 15 wt. % to 70 wt. %, 20 wt. % to 60 wt. %, or 25 wt. % to 50 wt. %, of a processed LLDPE recyclate and from 10 wt. % to 95 wt. %, 20 wt. % to 90 wt. %, 30 wt. % to 85 wt. %, 40 wt. % to 80 wt. %, or 50 wt. % to 75 wt.
- the virgin LLDPE is visbroken.
- Such visbreaking of virgin LLDPE can be thermal visbreaking and/or peroxidation visbreaking.
- such visbreaking conditions for a virgin LLDPE consist of thermal visbreaking at a temperature above the melting point of the LLDPE, greater than or equal to 300° C., or in the range of from 320° C. to 400° C., in the absence of or substantially in the absence of oxygen.
- the blends of processed LLDPE recyclate and a polyolefin blend component in combination with or independently of the blend ratios in the preceding paragraph, comprise a bimodal polymer, wherein the processed LLDPE recyclate product has a weight average molecular weight (“M w3 ”), the polyolefin blend component has a weight average molecular weight (“M w4 ”); and M w3 /M w4 is either less than or equal to 0.9, 0.8, 0.7, 0.6, or 0.5, or alternatively is greater than or equal to 1.1, 1.25, 1.5, 1.75, or 2.0.
- M w3 weight average molecular weight
- M w4 weight average molecular weight
- M w3 /M w4 is either less than or equal to 0.9, 0.8, 0.7, 0.6, or 0.5, or alternatively is greater than or equal to 1.1, 1.25, 1.5, 1.75, or 2.0.
- a method for processing linear low density polyethylene (LLDPE) recyclate comprises providing a LLDPE recyclate feedstock, adding the LLDPE recyclate to a first extruder to produce a first LLDPE recyclate melt, and subjecting the first LLDPE recyclate melt to visbreaking conditions to produce a second LLDPE recyclate melt.
- LLDPE linear low density polyethylene
- the LLDPE recyclate feedstock has: a first density in the range of from 0.910 g/cm 3 to 0.940 g/cm 3 ; a first melt index (2.16 kg, 190° C.) less than or equal to 5.0 g/10 min; a first molecular weight distribution (M w /M n ) greater than or equal to 5.0, greater than or equal to 7.0, greater than or equal to 10.0, or greater than or equal to 15.0; a first weight average molecular weight (“M w1 ”) greater than or equal to 85,000 daltons, greater than or equal to 120,000 daltons, greater than or equal to 180,000 daltons, or greater than or equal to 200,000 daltons, and/or less than or equal to 500,000 daltons, less than or equal to 400,000 daltons, less than or equal to 350,000 daltons, or less than or equal to 250,000 daltons; and a first melt elasticity (“ER”) greater than or equal to 0.5.
- the second LLDPE recyclate melt has: a second density, wherein the ratio of the second density to the first density is greater than or equal to 1.0; a second melt index, wherein the ratio of the second melt index to the first melt index is greater than or equal to 5.0, and/or the processed LLDPE recyclate has a melt index (I 2 ) greater than or equal to 5.0 g/10 min.; a second molecular weight distribution, wherein the ratio of second molecular weight distribution to the first molecular weight distribution is less than or equal to 0.8, and/or the molecular weight distribution of the processed LLDPE recyclate is less than or equal to 5.0; a second weight average molecular weight (“M w2 ”), wherein M w2 /M w1 i is less than or equal to 0.90 or less than or equal to 0.80; and a second melt elasticity, wherein the ratio of the second melt elasticity to the first melt elasticity is less than or equal to 0.50, less than or equal to 0.
- the method is additionally characterized by one or more of the following:
- the foregoing method further comprises forming a LLDPE recyclate product by withdrawal of the second LLDPE recyclate melt from the first extruder for further processing or pelletizing of the second LLDPE recyclate melt.
- the LLDPE recyclate product and a first polyolefin blend component are added to a second extruder, and compounding conditions are effected in the second extruder to form a polyolefin product comprising the melt-blended mixture of the processed LLDPE recyclate product and the first polyolefin blend component.
- compounding condition include a temperature less than or equal to 300° C.
- the first polyolefin blend component comprises a virgin polyolefin, a polyolefin recyclate feedstock, a processed polyolefin recyclate, or a combination thereof.
- the virgin polyolefin comprises a virgin LDPE, a virgin LLDPE, a virgin HDPE, a virgin MDPE, a virgin polypropylene, or a combination thereof;
- the polyolefin recyclate feedstock comprises a LDPE recyclate feedstock, a LLDPE recyclate feedstock, a HDPE recyclate feedstock, a MDPE recyclate feedstock, a polypropylene recyclate feedstock, or a combination thereof;
- the processed polyolefin recyclate comprises a processed LDPE recyclate, a second processed LLDPE recyclate, a processed HDPE recyclate, a processed MDPE recyclate, a processed polypropylene recyclate, or a combination thereof.
- the first polyolefin blend component comprises a virgin LLDPE, a LLDPE recyclate feedstock, a processed LLDPE recyclate, or a combination thereof
- the LLDPE recyclate product is added in an amount in the range of from 5 wt. % to 90 wt. %, or from 20 wt. % to 60 wt. %, based on the combined weight of the LLDPE recyclate product and the first polyolefin blend component; and/or the LLDPE recyclate product has third weight average molecular weight (“M w3 ”), the first polyolefin blend component has a fourth weight average molecular weight (“M w4 ”), and the M w3 /M w3 is either less than or equal to 0.8 or greater than or equal to 1.25.
- the first polyolefin blend component is a first virgin LLDPE comprising a polymer product prepared in a first polymerization apparatus, wherein in some instances, the polymer product was subjected to a visbreaking process after polymerization, and in some embodiments, the visbreaking process comprises thermal visbreaking, peroxide visbreaking, or a combination thereof.
- the first polyolefin blend component comprises a polyolefin powder prepared in a first polymerization apparatus.
- an antioxidant agent is added to the second extruder.
- the method further comprises: adding a second polyolefin blend component to a third extruder; effecting melt conditions in the third extruder to produce a second polyolefin blend component melt; and withdrawing the second polyolefin blend component melt as the first polyolefin blend component.
- the second polyolefin blend component comprises a virgin LLDPE, a LLDPE recyclate feedstock, a processed LLDPE recyclate, or a combination thereof.
- the second polyolefin blend component is subjected to a visbreaking process after polymerization, wherein in some instances, the visbreaking process consists of thermal visbreaking.
- the second polyolefin blend component comprises polyethylene powder prepared in a second polymerization apparatus and/or polyethylene pellets.
- the first and/or second polymerization apparatus each comprise two more polymerization reactors and/or two or more polymerization zones within a polymerization reactor.
- the first and/or second polymerization apparatuses each comprise two or more gas phase fluidized-bed reactors in series, two or more slurry phase reactors in series, or a gas phase fluidized-bed reactor in series with a multizone circulation reactor.
- an antioxidant agent is added to the third extruder.
- a composition comprise a polymer blend of a first polymer and a second polymer.
- the first polymer is a first processed LLDPE recyclate and is present in an amount in the range of from 5 wt. % to 90 wt. %.
- the second polymer is a virgin polyolefin, a polyolefin recyclate feedstock, a processed polyolefin recyclate, or a combination thereof, and is present in an amount in the range of from 10 wt. % to 95 wt. %. All weight percentages are based on the combined weight of the first and second polymers.
- the virgin polyolefin comprises a virgin LDPE, a virgin LLDPE, a virgin HDPE, a virgin MDPE, a virgin polypropylene, or a combination thereof
- the polyolefin recyclate feedstock comprises a LDPE recyclate feedstock, a LLDPE recyclate feedstock, a HDPE recyclate feedstock, a MDPE recyclate feedstock, a polypropylene recyclate feedstock, or a combination thereof
- the processed polyolefin recyclate comprises a processed LDPE recyclate, a second processed LLDPE recyclate, a processed HDPE recyclate, a processed MDPE recyclate, a processed polypropylene recyclate, or a combination thereof.
- processed means subjected to thermal visbreaking or subjected to thermal visbreaking and devolatilization.
- a blend comprises a visbroken LLDPE, having a first I 2 and a virgin LLDPE, a LLDPE recyclate feedstock, a processed LLDPE recyclate, or a combination thereof, having a second I 2 , wherein:
- the following examples use commercial LLDPE compositions having a low melt index as proxies for LLDPE recyclate feedstocks. After processing, as described herein, the visbroken low melt index LLDPEs, either alone or in blends with other components, are compared to higher melt index virgin LLDPEs.
- Densities are determined in accordance with ASTM D-4703 and ASTM D-1505/ISO-1183.
- High load melt index (“I 21 ”) was determined by ASTM D-1238-F (190° C./21.6 kg).
- Shear rheological measurements are performed in accord with ASTM 4440-95a, which characterize dynamic viscoelastic properties (storage modulus, G′, loss modulus, G′′ and complex viscosity, ⁇ *, as a function of oscillation frequency, ⁇ ).
- a rotational rheometer (TA Instruments) is used for the rheological measurements.
- a 25 mm parallel-plate fixture was utilized. Samples were compression molded in disks ( ⁇ 29 mm diameter and ⁇ 1.3 mm thickness) using a hot press at 190° C.
- An oscillatory frequency sweep experiment (from 398.1 rad/s to 0.0251 rad/s) was applied at 190° C.
- the applied strain amplitude is ⁇ 10% and the operating gap is set at 1 mm. Nitrogen flow was applied in the sample chamber to minimize thermal oxidation during the measurement.
- ER Melt elasticity
- the ratio ⁇ * 0.1 / ⁇ * 100 of complex viscosities, 0.1, at a frequency of 0.1 rad/sec and ⁇ * 100 , at a frequency of 100 rad/sec, is used as an additional measure of shear sensitivity and thus rheological breadth, or polydispersity, of the polymer melt.
- MWD molecular weight distribution
- M n number-average molecular weight
- M w weight-average molecular weight
- M z z-average molecular weight
- M n , M w , M z , MWD, and short chain branching (SCB) profiles are reported using the IR detector, whereas long chain branch parameter, g′, is determined using the combination of viscometer and IR detector at 145° C.
- Three Agilent PLgel Olexis GPC columns are used at 145° C. for the polymer fractionation based on the hydrodynamic size in 1,2,4-trichlorobenzene (TCB) with 300 ppm antioxidant butylated hydroxytoluene (BHT) as the mobile phase. 16 mg polymer is weighted in a 10 mL vial and sealed for the GPC measurement. The dissolution process is obtained automatically (in 8 ml TCB) at 160° C.
- the comonomer compositions are reported based on different calibration profiles obtained using a series of relatively narrow polyethylene (polyethylene with 1-hexene and 1-octene comonomer were provided by Polymer Char, and polyethylene with 1-butene were synthesized internally) with known values of CH 3 /1000 total carbon, determined by an established solution NMR technique. GPC one software was used to analyze the data.
- the long chain branch parameter, g′ is determined by the equation:
- [ ⁇ ] is the average intrinsic viscosity of the polymer that is derived by summation of the slices over the GPC profiles as follows:
- [ ⁇ ] i is the concentration of a particular slice obtained from IR detector
- [ ⁇ ] i is the intrinsic viscosity of the slice measured from the viscometer detector.
- VOC Volatile Organic Compounds
- P-GC/MS pyrolysis-gas chromatography/mass spectrometry
- Zero-shear viscosity ⁇ 0 is determined using the Sabia equation fit of dynamic complex viscosity versus radian frequency, as described in of Shroff & Mavridis, (1999) “A Long Chain Branching Index for Essentially Linear Polyethylenes”, Macromolecules, 32, 8454-8464 (with focus on Appendix B), the disclosure of which is fully incorporated by reference herein in its entirety.
- Equation 13 and its application are described in of Shroff & Mavridis, (1999) “A Long Chain Branching Index for Essentially Linear Polyethylenes”, Macromolecules, 32, 8454-8464, the disclosure of which is fully incorporated by reference herein in its entirety.
- Long Chain Branching frequency characterized by the ratio of Long Chain Branches per million carbon atoms, or LCB/10 6 C
- LCB/10 6 C Long Chain Branching frequency was determined by the method of Janzen & Colby (J. Janzen and R. H. Colby, “Diagnosing long-chain branching in polyethylenes”, Journal of Molecular Structure, Vol 485-486, 10 Aug. 1999, Pages 569-583), using eqs.(2-3) and the constants of Table 2 in the above reference.
- the zero-shear viscosity at 190° C., ⁇ * 0 is determined by extrapolation of the complex viscosity data via the Sabia equation, as described separately.
- the weight-average-molecular weight, M w is determined via GPC.
- the Long Chain Branching frequency, LCB/10 6 C can be determined numerically such that all 3 parameters ( ⁇ 0 , M w and LCB/10 6 C) satisfy eqs. (2-3) in the above reference.
- the lowermost value of LCB/10 6 C was always selected at the given ratio of ⁇ 0 / ⁇ 0,linear .
- Examples 1-3 in TABLE 2 show the results of visbreaking a LLDPE resin.
- P1 is believed to fairly represent an LLDPE recyclate feedstock.
- P1 LLDPE recyclate feedstock proxy
- melt index I 2 melt index I 2 of 2.1 g/10 min.
- Example 1 results in TABLE 2 show a number of other properties of P1.
- Examples 2 and 3 were prepared by visbreaking portions of P1. Visbreaking was performed by feeding P1 into a Werner and Pfleiderer ZSK40 twin screw extruder at a feed rate of 50 pounds per hour, a screw speed of 600 rpm and with a target temperature profile of 200/250/325/325/325/325/325/325/325/325° C. (from feed inlet to die). The extrudate was comminuted to pellets. In Examples 2 and 3 different screw designs were used resulting in increased energy input into the polymer in the extruder in Example 3 versus Example 2. The visbroken P1 of Example 2 using the first extruder screw design is labeled P1-vb1, and the visbroken P1 of Example 3 using the second extruder screw design is labeled P1-vb2, in TABLE 2.
- Example 2 shows that melt index I 2 of P1 is increased by visbreaking by a factor of 6.4, while density increased only nominally.
- Example 3 shows that melt index I 2 of P1 is increased by visbreaking by a factor of 7.2. Differences in melt index I 2 in Examples 2 and 3 are attributed to specific energy (“SPE”) input to the polymers of 0.498 kW ⁇ hr/kg and 0.540 kW ⁇ hr/kg, respectively.
- SPE specific energy
- Examples shows that high load melt index I 21 of P1 is increased by visbreaking by a factor of 4.9, and producing a reduction of melt index ratio (I 21 /I 2 ) from 29 to 22.
- Melt elasticity (“ER”) is reduced by about half in both Examples 2 and 3.
- Overall polydispersity measure (“PDR”) is reduced by about one thirds for both Examples 2 and 3.
- M n number average molecular weight
- M w weight average molecular weight
- M z Z-average molecular weight
- Molecular weight distribution (M w /M n ) is reduced by 28% and 21%
- molecular weight ratio (M z /M w ) is reduced by 19% and 20%, in Examples 2 and 3, respectively.
- Dynamic oscillatory data generated based on analysis of samples of P1, P1-vb1, and P1-vb2 are shown in TABLE 3 below.
- the data in TABLE 3 show that complex viscosity decreases as frequency increases for all of P1, P1-vb1, and P1-vb2.
- TABLE 3 further shows that visbreaking P1 results in a lower complex viscosity ( ⁇ *) for P1-vb1 and P1-vb2 for all tested values of frequency. Additionally, the difference in complex viscosity between P1 and both P1-vb1 and P1-vb2 decreases as frequency increase.
- FIG. 4 a comparison of curves generated for Examples 1-3 from the data in TABLE 3.
- the overlaid graphs show the log of complex viscosity ( ⁇ *) in poise as a function of the log of the oscillatory frequency in radians per second.
- Example 1 Example 2
- Example 3 Oscillation (P1) (P2) (P3) Freq.
- FIG. 5 a comparison of molecular weight curves generated for Examples 1-3.
- the overlaid graphs demonstrate both the reduction in molecular weight and narrowing of molecular weight distribution accomplished through visbreaking.
- any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited.
- ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited.
- within a range includes every point or individual value between its end points even though not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.
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US11976183B1 (en) * | 2022-12-19 | 2024-05-07 | Basell Polyolefine Gmbh | Process for modifiyng the melt flow index of low density polyethylene |
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- 2022-06-21 JP JP2023577837A patent/JP2024526561A/ja active Pending
- 2022-06-21 EP EP22744021.1A patent/EP4359466A1/fr active Pending
- 2022-06-21 CA CA3222511A patent/CA3222511A1/fr active Pending
- 2022-06-21 WO PCT/US2022/034377 patent/WO2022271726A1/fr active Application Filing
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11976184B1 (en) * | 2022-12-19 | 2024-05-07 | Basell Polyolefine Gmbh | Process for modifiyng the melt flow index of low density polyethylene |
US11976183B1 (en) * | 2022-12-19 | 2024-05-07 | Basell Polyolefine Gmbh | Process for modifiyng the melt flow index of low density polyethylene |
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