Post-industrial recyclates and methods thereof

Abstract

A method of recycling polymeric fines includes polymerizing a plurality of a-olefins in a polymerization reactor to obtain a plurality of polymer product particles, the polymer product particles comprising a plurality of polymeric fines. The method includes separating the plurality of polymer product particles from the plurality of polymeric fines to form a post-industrial recyclate (PIR) resin. The method includes blending a portion of the plurality of polymeric fines with the PIR resin to form a fines recycled resin.

Description

POST-INDUSTRIAL RECYCLATES AND METHODS THEREOF Field of the Invention

[0001] The current disclosure relates to methods of production and manufacture of post-industrial recyclates. Background of the Invention

[0002] Gas-phase fluidized-bed polymerizations are common processes by which polyolefin materials are commercially produced, much in part due to its economic viability. As such, much work has been implemented into catalyst and catalyst support design to improve the efficiencies and catalyst activities of such polymerizations. However, such gas-phase polymerizations often produce fines content, a by-product of the polymerization, which can cause differences from the target polymer properties and potentially form destructive deposits within a gas-phase fluidized- bed reactor. While there have been efforts to collect and store resulting polymeric fines, collection, transport, and storage of such materials raises handling concerns, as the particles can statically energize.

[0003] In addition, post-industrial recyclates (PIRs) on the market are very high molecular weight and low melt index polymers. However, for compression molding or injection molding applications, low molecular weight and high melt index is needed.

[0004] Accordingly, there is a need to develop new strategies and methodologies to collect, store, and reintegrate such polymeric fines into the available material production feedstock as well as produce post-industrial recyclates having low molecular weight and high melt index. Summary of the Invention

[0005] The current disclosure relates to methods of production and manufacture of post-industrial recyclates.

[0006] In some embodiments, a method of recycling polymeric fines includes polymerizing a plurality of α-olefins in a polymerization reactor to obtain a plurality of polymer product particles, the polymer product particles comprising a plurality of polymeric fines. The method includes separating the plurality of polymer product particles from the plurality of polymeric fines to form a post-industrial recyclate (PIR) resin. The method includes blending a portion of the plurality of polymeric fines with the PIR resin to form a fines recycled resin.

[0007] In some embodiments, a method of recycling polymeric fines includes polymerizing a plurality of α-olefins in a polymerization reactor to obtain a plurality of polymer product particles, the polymer product particles comprising a plurality of polymeric fines. The method includes separating the plurality of polymer product particles from the plurality of polymeric fines to form a post-industrial recyclate (PIR) resin. The method includes blending a portion of the plurality ofpolymeric fines with the PIR resin to form a fines recycled resin, wherein the fines recycled resin comprises about 0.1 wt% to about 15 wt% of the plurality of polymeric fines. Detailed Description of the Invention

[0008] Resins of the current disclosure include components traditionally considered as process waste produced from gas-phase fluidized-bed and / or slurry polymerizations of α-olefin monomers. That is to say that resins of the current disclosure include polymeric fines removed from the product stream of the α-olefin polymerization blended within waste pellets produced from processing the product stream (referred to as post-industrial recyclate) of the α-olefin polymerization to form a “fines recycled resin”. In some embodiments, the post-industrial recyclate resin (PIR) is a polyolefin resin comprising polyethylene and / or polypropylene. In some embodiments, methods of producing fines recycled resins disclosed herein utilize polymeric fine collection (e.g., air separators) from newly synthesized polymers and integration of the fines with PIR resins to produce materials of suitable physical and mechanical properties for consumer use. Such processes described herein reduce process waste, as provide improved handling, transport, and disposal of polymeric fines. The resulting fines recycled resins of the present disclosure exhibit various mechanical and physical properties for implementation into various commercial processes and industries.

[0009] Processes of the present disclosure provide collecting and implementing polymeric fines, a traditionally discarded by-product of fluidized-bed gas-phase and / or slurry polymerizations, into post-industrial recyclate (PIR) resins to form fines recycled resins. Such processes described herein reduce process waste, as well as address challenges associated with the handling, transport, and disposal of polymeric fines. The resulting fines recycled resin of the present disclosure exhibit various mechanical and physical properties for implementation into various commercial processes and industries. For example, fines recycled resins of the present disclosure can provide improved molecular weight and melt index properties which provide compression molding and injection molding capability, as compared to PIRs currently on the market. Polyolefin production

[0010] In some embodiments, polyolefins, such as polyethylene and polypropylene, can be produced via a gas-phase polymerization process and / or a slurry polymerization. Gas-phase polymerization processes, as described herein, are economical processes for the polymerization of C2-C8-α-olefins. Such gas-phase polymerization processes can be carried out as gas-phase fluidized-bed processes, in which the polymer particles are kept in suspension by a suitable gas stream.

[0011] In general, a gas-phase fluidized-bed reactor is a relatively long tube through which reactor gas is circulated. The circulated reactor gas is fed in at the lower end of the gas-phase fluidized- bed reactor and is taken off again at its upper end. When the reactor is employed for the polymerization of α-olefins, the circulated reactor gas is preferably a mixture of the respective α- olefin or α-olefins and inert gases such as nitrogen and / or saturated hydrocarbons such as ethane, propane, butane, pentane and / or hexane. The velocity of the reactor gas has to be sufficiently high to fluidize the bed of finely divided polymer located in the tube and serving as polymerization zone and to remove the heat of polymerization effectively.

[0012] To obtain constant reaction conditions, the constituents of the reactor gas can be fed directly into the gas-phase fluidized-bed reactor or via the circulated reactor gas. In some embodiments, it can be advantageous to introduce the C2-C8-α-olefins directly into the gas-phase fluidized-bed reactor. Additionally, it can be advantageous to introduce the catalyst, and / or any cocatalysts used, directly into the fluidized bed of finely divided polymer using an inert gas.

[0013] In one or more embodiments, the polymerization catalyst can be a metallocene based catalyst system, which includes at least one of a (a) transition metal containing compound, (b) an activating compound, and / or (c) a support material. In some embodiments, an organic transition metal compound can include, at least, one or more compounds of transition metals of groups 3 to 12 of the Periodic Table and / or the lanthanides, which contain organic groups and form active catalysts for olefin polymerization, often after reaction with the components (b) and (c). Such compounds can include at least one monodentate or polydentate ligand is bound to the central atom via a sigma or pi bond. In such embodiments, such ligands can include both those containing cyclopentadienyl radicals and those which are free of cyclopentadienyl radicals. Furthermore, multinuclear cyclopentadienyl complexes are also suitable for olefin polymerization. In some embodiments, the polymerization of C2-C8-α-olefins is carried out using appropriate catalysts systems and reactor conditions for gas-phase fluidized-bed reactors as described in detail in, for example, EP-A-0475603, EP-A-0089691, and EP-A-0571826.

[0014] In some embodiments, a slurry polymerization may be utilized to prepare polyolefins. The slurry polymerization may be conducted in any known reactor used for slurry polymerization. Such reactors can include, but are not limited to, a continuous stirred tank reactor and a loop reactor. In such reactors, the slurry is circulated in an inert diluent with a high velocity along a closed piped through implementation of a circulation pump. In one or more embodiments, the inert diluent is a hydrocarbon diluent such as methane, ethane, propane, n-butane, isobutene, pentanes, hexanes, heptanes, octanes, and / or combinations thereof. Loop reactors are generally known in the art and examples are given, for instance, in U.S. Pat. Nos. 4,582,816, 3,405,109, 3,324,093, and 5,391,654.

[0015] Generally, the production rate in the slurry polymerization is suitably controlled with the catalyst feed rate. It is also possible to influence the production rate by suitable selection of the monomer concentration in the slurry polymerization medium. In some embodiments, the catalyst and monomer feeds may be introduced into the slurry polymerization simultaneously or sequentially. Additionally, general reactor design aspects known to one of ordinary skill in the art (e.g., temperature, pressure, time, etc.) may also be tuned / tailored to produce polyolefin materials having desired properties.

[0016] In at least one embodiment, such processing conditions are tailored to produce polyolefin materials having a weight average molecular weight (Mw), as determined by GPC, of about 40,000 g / mol to about 2,500,00 g / mol. In at least one embodiment, such processing conditions are tailored to produce polyolefin materials having a density, as determined by (as determined by ASTM D1505) of about 0.875 g / cm3to about 0.975 g / cm3. In at least one embodiment, such processing conditions are tailored to produce polyolefin materials having a melt index (as determined by ASTM D-1238, 190°C with a 2.16 kg load) of about 0.1 g / 10 min to about 20 g / 10 min.

[0017] In at least one embodiment, such processing conditions are tailored to produce polyethylene, or a copolymer thereof, having a weight average molecular weight (Mw), as determined by GPC, of about 40,000 g / mol to about 2,500,00 g / mol. In at least one embodiment, such processing conditions are tailored to produce polyethylene, or a copolymer thereof, having a density, as determined by (as determined by ASTM D1505) of about 0.89 g / cm3to about 0.975 g / cm3. In at least one embodiment, such processing conditions are tailored to produce polyethylene, or a copolymer thereof, having a melt index (as determined by ASTM D-1238, 190°C with a 2.16 kg load) of about 0.1 g / 10 min to about 20 g / 10 min, such as about 0.5 g / 10 min to about 15 g / 10 min, such as about 1 g / 10 min to about 10 g / 10 min such as about 2 g / 10 min to about 8 g / 10 min.

[0018] In at least one embodiment, such processing conditions are tailored to produce polypropylene, or a copolymer thereof, having a weight average molecular weight (Mw), as determined by GPC, of about 40,000 g / mol to about 2,500,00 g / mol. In at least one embodiment, such processing conditions are tailored to produce polypropylene, or a copolymer thereof, having a density, as determined by (as determined by ASTM D1505) of about 0.875 g / cm3to about 0.925 g / cm3, such as about 0.89 g / cm3to about 0.92 g / cm3, such as about 0.89 g / cm3to about 0.91 g / cm3, such as about 0.9 g / cm3. In at least one embodiment, such processing conditions are tailored to produce polypropylene, or a copolymer thereof, having a melt index (as determined by ASTM D- 1238, 190°C with a 2.16 kg load) of about 0.1 g / 10 min to about 20 g / 10 min, such as about 0.5 g / 10 min to about 15 g / 10 min, such as about 1 g / 10 min to about 10 g / 10 min such as about 2 g / 10 min to about 8 g / 10 min.

[0019] In some embodiments, fine particles can be developed during operation of the gas-phase fluidized-bed reactor and / or slurry polymerization reactor. Such particles may be discharged from the reactor via the circulating reactor media or can fall back into the fluidized bed. However, in some embodiments, the fine particles also have a tendency deposit and accumulate on the interior walls of such reactors resulting in deposit formation. Such deposits have a tendency to detach from the interior wall of these reactors and block the polymer product discharge apparatus. In some embodiments, smaller agglomerates (e.g., fines) are discharged from the gas-phase fluidized- bed reactor and / or slurry polymerization reactor together with the polymer product thereby deviating one or more properties of the polymer product from target properties.

[0020] The term “fines content” refers to the fraction of polymer product discharged from the gas- phase fluidized-bed reactor and / or slurry polymerization reactor having a particle size of about 0.27 cm or less. A high fines content can lead to drawbacks in polymer properties, such as handleability and flowability. In some embodiments, a high fines content can adversely affect transport of the polymer, such as pneumatic transport thereof. In addition, a high fines content can lead to electrostatic charging and / or dust accumulation during transport or storage of the polymer.

[0021] As such, it can be advantageous to separate the fines content from the polyolefin polymer product prior to material processing of the polymer product to circumvent such issues. Fine collection and product sortation

[0022] In some embodiments, fines are removed from the product stream of the gas-phase fluidized-bed reactor and / or slurry polymerization reactor via any method of separation by mass known to one of ordinary skill in the art. In at least one embodiment, one or more air separators (e.g., a Z-box) may be implemented to remove fines from the polyolefin product stream. In some embodiments, an air separator may employ one or more adjustable airflow sources and baffles to blow or remove fines and / or other light fragments from the polyolefin polymer product stream, the fines being collected in one or more collection silos. In at least one embodiment, the velocity of the airflow may be adjusted to increase / decrease the size of fines being removed from the polyolefin polymer product stream.

[0023] Additionally and / or alternatively, an air separator may include a “Z-box”. As is named in accordance to its shape, a Z-box operates via a gravity separation mechanism wherein particles fall through an upward air force. As such, lighter particles can become entrained in the upward airflow while heavier materials continue to fall throughout the apparatus. The “Z” shape forces the falling material to impact walls of the apparatus, thus releasing lighter materials that may be combined with heavier materials.

[0024] Additionally and / or alternatively, an air separator may include an air aspirator system. Generally, an air aspirator system operates by gravity feeding particles of the polyolefin polymerproduct stream into an apparatus having an upward air force such that lighter materials become entrained in the airflow and are removed out of one part of the system. Typically, the separators do not have the characteristic shape of a “Z-box”, but may have other features, such as baffles, to enhance separation of the product particles. Additionally, an air aspirator system may include multiple stages, or cascades wherein materials that fall through one stage may be introduced into a second stage and be further separated.

[0025] In at least one embodiment, fines are removed from the product stream of the gas-phase fluidized-bed reactor and / or slurry polymerization reactor via one or more air separators. As such, the velocity of the airflow is maintained at a constant velocity to continuously remove fines having a size of less than about 0.27 cm from the polyolefin polymer product stream, such as less than about 0.25 cm, such as less than about 0.22 cm, such as less than about 0.2 cm. In one or more embodiments, the removed fines are collected and pneumatically conveyed to and stored within a collection silo. In at least one embodiment, the collection silo is an electrically grounded collection silo.

[0026] In some embodiments, an anti-static agent may be integrated into the fines content stored within the collection silo. Additionally and / or alternatively, an anti-static agent may be incorporated in the fluidized-bed gas-phase reactor and / or slurry polymerization reactor during polyolefin formation and may be carried from the reactor to the collection silo within the fine content. Integration of such anti-static agents reduce electrostatic charging and / or dust aggravations during transport or storage of the collected fines. In one or more embodiments, the anti-static agent is present within the collection silo in an amount of about 1 ppm to about 50 ppm based on the total mass of the collected fines, such as about 1 ppm to about 40 ppm, such as about 1 ppm to about 30 ppm, such as about 1 ppm to about 20 ppm, such as about 1 ppm to about 10 ppm, such as about 1 ppm to about 5 ppm. In one or more alternative embodiments, the anti-static agent is present within the collection silo in an amount of about 1 ppm to about 5 ppm based on the total mass of the collected fines, alternatively about 5 ppm to about 10 ppm, alternatively about 10 ppm to about 50 ppm. In one or more embodiments, the anti-static agent can include salt mixtures comprising calcium salts of medialanic acid and / or chromium salts of N- stearylanthranilic acid, C12-C22 fatty acid soaps of alkali metals and / or alkaline earth metals, salts of sulfonic esters of the general formula (RR')-CHOSO3Me, esters of polyethylene glycols with fatty acids, polyoxyethylene alkyl ethers, and / or combinations thereof.

[0027] Upon having the fines removed therefrom, the product stream of the gas-phase fluidized- bed reactor and / or slurry polymerization reactor may be introduced into any one or more material processing apparatuses, such as an extruder, to form a polymeric resin extrudate. Additionally and / or alternatively, in one or more embodiments, one or more additive components may beadded / blended into the product stream during material processing and formation of the polymeric resin extrudate. Suitable additives include, but are not limited to, UV stabilizers, flame retardants, fillers, and pigments. Additives may be important in establishing the long term stability of the polymeric resin as well as the resulting material’s chemical and impact resistance.

[0028] In one or more embodiments, one or more UV stabilizers may be added to the product stream of the gas-phase fluidized-bed reactor and / or slurry polymerization reactor (after separation of fines therefrom) prior to and / or during formation of the polymeric resin extrudate. In at least one embodiment, one or more UV stabilizers in an amount of about 1500 ppm to about 2500 ppm based on the amount of product stream introduced into the one or more material processing apparatuses, such as about 1750 ppm to about 2250 ppm, such as about 2000 ppm. Suitable UV stabilizers include, but are not limited to, hindered amine light stabilizers ("HALS"). Examples of HALS include: Chimassorb 944, Chimassorb 994, Chimassorb 905, Tinuvin 770, Tinuvin 992, Tinuvin 622, Tinuvin 144, and Spinuvex A36 available from Geigy; and Cyasorb UV 3346 and Cyasorb UV 944 commercially available American Cyanamide. Particularly preferred UV stabilizers are Cytec UV 3346 and Chimassorb 944 (poly[N,N-bis(2,2,6,6-tetramethyl-4- piperidinyl)-1,6-hexanediamine-co-2,4-dichloro-6-morpholino-1,3,5-triazine).

[0029] In one or more embodiments, one or more flame retardants may be added to the product stream of the gas-phase fluidized-bed reactor and / or slurry polymerization reactor (after separation of fines therefrom) prior to and / or during formation of the polymeric resin extrudate. In at least one embodiment, one or more flame retardants in an amount of about 1500 ppm to about 2500 ppm based on the amount of product stream introduced into the one or more material processing apparatuses, such as about 1750 ppm to about 2250 ppm, such as about 2000 ppm. Flame retardants include, for example, halogen-containing compounds, antimony oxides, or phosphorus compounds. Suitable flame retardants include, but are not limited to aluminum trihydrate, antimony oxide (Sb2O3), and decabromobiphenyl oxide ("decabrome").

[0030] In some embodiments, melt screw extrusion is implemented to form the polymeric resin extrudate, which can then be further processed via pelletization to form a pelletized polymeric resin. Melt blending is one suitable method for preparing the final polymer blend of the present disclosure, although any suitable polymer blending techniques available to those of ordinary skill in the art may be used. Techniques for melt blending of a polymer with additives of all types are known to those of ordinary skill the art and can typically be used with the present disclosure. In one type of melt blending operation useful with the present disclosure, the individual components of the blend are combined in a mechanical extruder or mixer, and then heated to a temperature sufficient to form a polymer melt.

[0031] The mechanical mixer can be a continuous or batch mixer. Examples of suitable continuous mixers include single screw extruders, intermeshing co-rotating twin screw extruders such as Werner & Pfleiderer ZSK™ extruders, counter-rotating twin screw extruders such as those manufactured by Leistritz™, and reciprocating single screw kneaders such as Buss™ co-kneaders. Examples of suitable batch mixers are lateral 2-roll mixers such as Banbury™ or Boling™ mixers. The temperature of the melt, residence time of the melt within the mixer, and the mechanical design of the mixer are several well-known variables that control the amount of shear to be applied to the composition during mixing, and can be readily selected by one of ordinary skill in the art based on the disclosure of the disclosure herein.

[0032] The polymeric resin extrudate disclosed herein may be pelletized via strand pelleting or commercial underwater pelletization. Pellets of the polymeric resin may then be easily processed into shaped articles by injection molding, profile extrusion, blow molding, and other forming processes to give products which have well balanced properties suitable for commercial applications.

[0033] In at least one embodiment, pellets of the polymeric resin are formed in a continuous process. As such, components of the polymeric resin are fed into a continuous mixer, a single screw or twin screw extruder via volumetric or gravimetric feeders. The extruder is heated to a temperature sufficient to melt the polymers, for example between 150 ℃ and 500 ℃. The components are fed into an extruder and mixed / blended together in a molten state. The extruder speed may be from about 1 to about 1000 revolutions per minute (rpm), more typically from about 10 rpm to about 500 rpm. The gas from the extruder may be evacuated by a vacuum pump. The polymeric resin extrudate is typically cooled (e.g., in a water bath or underwater pelletizer) and pelletized to form pellets of the polymeric resin.

[0034] In at least one embodiment, pellets of the polymeric resin are formed in a batch process. As such, components of the polymeric resin are added to a mixing device, such as a Banbury mixer, and heated to a temperature sufficient to melt the polymer, such as about 150 ℃ to about 400 ℃. The mixing speed is typically about 1 to about 100 rpm. The output from the mixer was cooled and pelletized to form pellets of the polymeric resin.

[0035] In some embodiments, pellets of the polymeric resin are passed through a classifier and sorted in accordance to their size via any one or more methods known to one of ordinary skill in the art. In one or more embodiments, the plurality of polymeric resin pellets may be passed through a first size exclusion filter to remove undersized pellets therefrom, wherein the undersized pellets may be characterized as having a size density of less than about 0.6 g / 30 pellets, such as less than about 0.55 g / 30 pellets, such as less than about 0.5 g / 30 pellets. In one or more embodiments, the undersized pellets may be collected and stored within a closed supersack for useas a post-industrial recyclate resin (PIR). In one or more embodiments, the filtered polymeric resin pellets may be passed through a second size exclusion filter to remove oversized pellets therefrom, wherein the oversized pellets may be characterized as having a size density of greater than about 2 g / 10 pellets, such as greater than about 1.5 g / 10 pellets, such as greater than about 1 g / 10 pellets. In one or more embodiments, the overized pellets may be collected and stored within a closed supersack for use as a PIR. In one or more embodiments, the resulting and appropriately sized polymeric resin pellets are collected and stored for further product manufacturing processes.

[0036] In at least one embodiment, such processing conditions produce polyethylene resin having a density, as determined by ASTM D1505, of about 0.89 g / cm3to about 0.975 g / cm3, such as about 0.915 g / cm3to about 0.94 g / cm3, such as about 0.93 g / cm3to about 0.935 g / cm3, such as about 0.935 g / cm3. In at least one embodiment, such processing conditions produce polyethylene resin having a melt index (as determined by ASTM D-1238, 190°C with a 2.16 kg load) of about 0.1 g / 10 min to about 20 g / 10 min, such as about 0.5 g / 10 min to about 15 g / 10 min, such as about 1 g / 10 min to about 10 g / 10 min such as about 2 g / 10 min to about 8 g / 10 min.

[0037] In one or more embodiments, the polyethylene resin is selected from the group consisting of ultra-high molecular weight polyethylene (UHMWPE), ultra-low molecular weight polyethylene (ULMWPE), high molecular weight polyethylene (HMWPE), high density polyethylene (HDPE), medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), very-low density polyethylene (VLDPE), and combinations thereof. In some embodiments, the polyethylene resin is a copolymer derivative of polyethylene and any one or more C3-C8-α-olefin monomers.

[0038] In some embodiments, the polyethylene resin is a HDPE resin has a density (as determined by ASTM1505) of about 0.940 g / cm3to about 0.975 g / cm3, such as about 0.940 g / cm3to about 0.960 g / cm3, such as about 0.940 g / cm3to about 0.955 g / cm3, such as about 0.953 g / cm3. In some embodiments, the HDPE resin has a high load melt index (HLMI) (as determined by ASTM D- 1238, 190°C with a 21.6 kg load) of about 2 g / 10 min to about 10 g / 10 min, such as about 4 g / 10 min to about 8 g / 10 min, such as about 5.5 g / 10 min to about 7.5 g / 10 min.

[0039] In some embodiments, the polyethylene resin is a LLDPE resin has a density (as determined by ASTM1505) of about 0.89 g / cm3to about 0.93 g / cm3, such as about 0.9 g / cm3to about 0.92 g / cm3, such as about 0.9 g / cm3to about 0.915 g / cm3. In some embodiments, the LLDPE resin has a melt index (MI) (as determined by ASTM D-1238, 190°C with a 2.16 kg load) of about 0.1 g / 10 min to about 10 g / 10 min, such as about 0.5 g / 10 min to about 5 g / 10 min, such as about 1 g / 10 min to about 5 g / 10 min.

[0040] In some embodiments, the polyethylene resin is a LDPE resin has a density (as determined by ASTM1505) of about 0.915 g / cm3to about 0.935 g / cm3, such as about 0.925 g / cm3to about0.935 g / cm3, such as about 0.925 g / cm3to about 0.93 g / cm3. In some embodiments, the LDPE resin has a melt index (MI) (as determined by ASTM D-1238, 190°C with a 2.16 kg load) of about 0.5 g / 10 min to about 15 g / 10 min, such as about 1 g / 10 min to about 10 g / 10 min, such as about 5 g / 10 min to about 10 g / 10 min.

[0041] In at least one embodiment, such processing conditions produce polypropylene resin having a density, as determined by ASTM D1505, of about 0.875 g / cm3to about 0.925 g / cm3, such as about 0.89 g / cm3to about 0.92 g / cm3, such as about 0.89 g / cm3to about 0.91 g / cm3, such as about 0.9 g / cm3. In at least one embodiment, such processing conditions produce polypropylene resin having a melt index (as determined by ASTM D-1238, 190°C with a 2.16 kg load) of about 0.1 g / 10 min to about 20 g / 10 min, such as about 0.5 g / 10 min to about 15 g / 10 min, such as about 1 g / 10 min to about 10 g / 10 min such as about 2 g / 10 min to about 8 g / 10 min. Fine reprocessing

[0042] In some embodiments, the collected fines and PIR may be blended together to form a fines recycled resin. In one or more embodiments, a fines recycled resin may include one of the collected fines and the undersized pellets or oversized pellets or combinations thereof. In at least one embodiment, the collected fines are about 0.1 wt% to about 15 wt% of the fines recycled resin, such as about 0.5 wt% to about 12.5 wt%, such as about 1 wt% to about 10 wt%. In at least one embodiment, the undersized pellets make up about 99.9 wt% to about 10 wt% of the fines recycled resin, such as about 99.5 wt% to about 25 wt%, such as about 99 wt% to about 50 wt%. In at least one embodiment, the oversized pellets make up about 99.9 wt% to about 10 wt% of the fines recycled resin, such as about 99.5 wt% to about 25 wt%, such as about 99 wt% to about 50 wt%.

[0043] A fines recycled resin of the present disclosure can be formed using any suitable extrusion process, such as those described above, and / or include any suitable additives, such as those described above. In some embodiments, the components of a fines recycled resin (e.g., polymeric fines and PIR resin) may be introduced to an extrusion apparatus through a loss in weight feeder. In one or more embodiments, melt screw extrusion is implemented to form the fines recycled resin extrudate, which can then be further processed via pelletization to form a pelletized fines recycled resin. Melt blending is one suitable method for preparing the fines recycled resin of the present disclosure, although any suitable polymer blending techniques available to those of ordinary skill in the art may be used. Techniques for melt blending of a polymer with additives of all types are known to those of ordinary skill the art and can typically be used with the present disclosure. In one type of melt blending operation useful with the present disclosure, the individual components of the blend are combined in a mechanical extruder or mixer, and then heated to a temperature sufficient to form a polymer melt.Fines recycled resin properties

[0044] In some embodiments, a PIR and a plurality of polyethylene fines may be blended together to form a polyethylene fines recycled resin. In at least one embodiment, such processing conditions produce polyethylene fines recycled resin having a density, as determined by ASTM D1505, of about 0.89 g / cm3to about 0.975 g / cm3, such as about 0.915 g / cm3to about 0.94 g / cm3, such as about 0.935 g / cm3to about 0.93 g / cm3, such as about 0.935 g / cm3. In at least one embodiment, such processing conditions produce polyethylene fines recycled resin having a melt index (as determined by ASTM D-1238, 190°C with a 2.16 kg load) of about 0.1 g / 10 min to about 20 g / 10 min, such as about 0.5 g / 10 min to about 15 g / 10 min, such as about 1 g / 10 min to about 10 g / 10 min such as about 2 g / 10 min to about 8 g / 10 min.

[0045] The secant modulus of the polyethylene fines recycled resin is determined in accordance to ASTM D882 (1% Secant). In some embodiments, the polyethylene fines recycled resin has a secant modulus of about 50,000 psi to about 200,000 psi, such as about 75,000 psi to about 175,000 psi, such as about 100,000 psi to about 150,000 psi.

[0046] The tensile strength at yield of the polyethylene fines recycled resin is determined in accordance to ASTM D882. about 2,000 psi to about 10,000 psi, such as about 4,000 psi to about 8,000 psi, such as about 5,000 psi to about 7,000 psi. In some embodiments, the polyethylene fines recycled resin has a tensile strength at yield of greater than 10,000 psi.

[0047] In some embodiments, a PIR and a plurality of plurality of polypropylene fines may be blended together to form a polypropylene fines recycled resin. In at least one embodiment, such processing conditions produce polypropylene fines recycled resin having a density, as determined by ASTM D1505, of about 0.875 g / cm3to about 0.925 g / cm3, such as about 0.89 g / cm3to about 0.92 g / cm3, such as about 0.89 g / cm3to about 0.91 g / cm3. In at least one embodiment, such processing conditions produce polypropylene fines recycled resin having a melt index (as determined by ASTM D-1238, 190°C with a 2.16 kg load) of about 0.1 g / 10 min to about 20 g / 10 min, such as about 0.5 g / 10 min to about 15 g / 10 min, such as about 1 g / 10 min to about 10 g / 10 min such as about 2 g / 10 min to about 8 g / 10 min.

[0048] The secant modulus of the polypropylene fines recycled resin is determined in accordance to ASTM D882 (1% Secant). In some embodiments, the polypropylene fines recycled resin has a secant modulus of about 150,000 psi to about 300,000 psi, such as about 200,000 psi to about 275,000 psi, such as about 225,000 psi to about 250,000 psi.

[0049] The tensile strength at yield of the polypropylene fines recycled resin is determined in accordance to ASTM D256. In some embodiments, the polypropylene fines recycled resin has a tensile strength at yield of about 2,000 psi to about 10,000 psi, such as about 4,000 psi to about8,000 psi, such as about 5,000 psi to about 7,000 psi. In some embodiments, the polypropylene fines recycled resin has a tensile strength at yield of greater than 10,000 psi. End Uses

[0050] In one or more embodiments, the fines recycled resin, or pellets thereof, is useful for making articles by injection molding, blow molding, rotomolding, compression molding, and the like. The fines recycled resin is also useful for making films, extrusion coatings, pipes, sheets, fibers, and the like. Products that can be made from the resin include sheets, films, bags, conduit, tanks, outdoor equipment, cups, containers, closures, dispensers, toys; medical components like syringes, vials, specimen bottles, pipette tips; automotive parts like battery cases, bumper panels, interior and exterior door trims, and the like..

[0051] In some embodiments, the fines recycled resin is suitable for producing pipes or piping components. In general, materials and products produced using the polymeric resin exhibit environmental stress crack resistance and tensile properties required for use in conduit pipe applications, as outlined in ASTM F2160, UL651A, and NEMA TC-7 (incorporated herein by reference). ASTM F2160 is the primary standard to meet where the minimum cell classification as defined by ASTM D3350 is PE334480C or E, where material property thresholds pertaining to density, melt index, flexural modulus, tensile strength at yield, and crack growth resistance should be satisfied. Examples

[0052] HDPE can be synthesized in a gas-phase fluidized-bed reactor, wherein the prescribed reactor conditions and procedures follow those described in U.S. Pat. No.7,834,107. The product stream exiting the gas-phase fluidized-bed reactor is then subjected to a series of air separators, through which polymeric fines are removed from the polyolefin polymer product. The polymeric fines are then collected and provided to an electrically grounded silo. Additionally, an anti-static agent is added to the electrically grounded silo to remove static charge from the polymeric fines. The polyolefin polymer product can be introduced to an extrusion apparatus to form a polymer extrudate, which is then pelletized and sorted based on pellet size. Pellets deemed to have sizes outside the desired range can be collected as post-industrial recyclate (PIR) resin. The PIR resin and polymeric fines can then be introduced to an extrusion apparatus via a loss in weight feeder to form an HDPE fines recycled resin. The HDPE fines recycled resin can then be subjected to multiple ASTM test methods to determine various physical and mechanical properties of the material, such as density (as determined in accordance to ASTM D1505), melt flow index (as determined in accordance to ASTM D-1238, 190°C with a 2.16 kg load), flexural modulus (asdetermined in accordance to ASTM D790), tensile strength at yield (as determined in accordance to ASTM D-638), and the like.

[0053] Overall, processes of the present disclosure provide collecting and implementing polymeric fines, a traditionally discarded by-product of fluidized-bed gas-phase and / or slurry polymerizations, into post-industrial recyclate (PIR) resins to form fines recycled resins. Such processes described herein reduce process waste, as well as address challenges associated with the handling, transport, and disposal of polymeric fines. The resulting fines recycled resin of the present disclosure exhibit various mechanical and physical properties for implementation into various commercial processes and industries. For example, fines recycled resins of the present disclosure can provide improved molecular weight and melt index properties that provide compression molding and injection molding capability, as compared to PIRs currently on the market.

[0054] The phrases, unless otherwise specified, "consists essentially of" and "consisting essentially of" do not exclude the presence of other steps, elements, or materials, whether or not, specifically mentioned in this specification, so long as such steps, elements, or materials, do not affect the basic and novel characteristics of the present disclosure, additionally, they do not exclude impurities and variances normally associated with the elements and materials used.

[0055] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from 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. Additionally, 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.

[0056] All documents described herein are incorporated by reference herein, including any priority documents and or testing procedures to the extent they are not inconsistent with this text. As is apparent from the foregoing general description and the specific embodiments, while forms of the present disclosure have been illustrated and described, various modifications can be made without departing from the spirit and scope of the present disclosure. Accordingly, it is not intended that the present disclosure be limited thereby. Likewise, the term “comprising” is considered synonymous with the term “including” for purposes of United States law. Likewise whenever a composition, an element or a group of elements is preceded with the transitional phrase “comprising,” it is understood that we also contemplate the same composition or group of elementswith transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “is” preceding the recitation of the composition, element, or elements and vice versa.

[0057] While the present disclosure has been described with respect to a number of embodiments and examples, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope and spirit of the present disclosure.

Claims

CLAIMS 1. A method of recycling polymeric fines, the method comprising: polymerizing a plurality of α-olefins in a polymerization reactor to obtain a plurality of polymer product particles, the polymer product particles comprising a plurality of polymeric fines; separating the plurality of polymer product particles from the plurality of polymeric fines to form a post-industrial recyclate (PIR) resin; and blending a portion of the plurality of polymeric fines with at least a portion of the PIR resin to form a fines recycled resin.

2. The method of claim 1, wherein the plurality of α-olefins is selected from the group consisting of C2-C8-α-olefins and combinations thereof.

3. The method of claim 1, wherein the plurality of α-olefins is selected from the group consisting of ethylene, propylene, and combinations thereof.

4. The method of claim 1, wherein the plurality of polymeric fines comprise a size of less than about 0.27 cm.

5. The method of claim 1, wherein the method further comprises collecting and storing the plurality of polymer fines within an electrically grounded collection silo.

6. The method of claim 5, wherein collecting and storing the plurality of polymeric fines further comprises introducing an anti-static agent to the electrically grounded collection silo.

7. The method of claim 6, wherein the anti-static agent is present within the electrically grounded collection silo in an amount of about 1 ppm to about 50 ppm based on the total mass of the plurality of polymeric fines present therein.

8. The method of claim 1, wherein the method further comprises: extruding the plurality of polymeric product particles at a temperature of about 150 ℃ to about 500 ℃ and an extruder speed of about 1 rpm to about 1000 rpm to form a polymeric resin extrudate; pelletizing the polymeric resin extrudate to form a plurality of polymeric resin pellets; and sorting the plurality of polymeric resin pellets into a plurality of pellets having a first size and a plurality or pellets having a second size, wherein the PIR resin comprises the plurality of pellets having the second size.

9. The method of claim 8, wherein the plurality of pellets having the second size comprises pellets having a size density of less than about 0.6 g / 30 pellets.

10. The method of claim 8, wherein the plurality of pellets having the second size comprises pellets having a size density of greater than about 1 g / 10 pellets.

11. The method of claim 1, wherein blending the plurality of polymeric fines with the PIR resin further comprises introducing the plurality of polymeric fines and the PIR resin to a melt screw extrusion apparatus, via a loss in weight feeder, to form a mixture and extruding the mixture to form an extrudate comprising the fines recycled resin.

12. The method of claim 1, wherein the fines recycled resin comprises about 0.1 wt% to about 15 wt% of the plurality of polymeric fines.

13. A method of recycling polymeric fines, the method comprising: polymerizing a plurality of α-olefins in a polymerization reactor to obtain a plurality of polymer product particles, the polymer product particles comprising a plurality of polymeric fines; separating the plurality of polymer product particles from the plurality of polymeric fines to form a post-industrial recyclate (PIR) resin; and blending a portion of the plurality of polymeric fines with the PIR resin to form a fines recycled resin, wherein the fines recycled resin comprises about 0.1 wt% to about 15 wt% of the plurality of polymeric fines.

14. The method of claim 13, wherein the plurality of polymeric fines comprises a size of less than about 0.27 cm.

15. The method of claim 13, wherein the plurality of polymeric fines comprises polyethylene fines.

16. The method of claim 15, wherein the PIR resin comprises polyethylene.

17. The method of claim 15, wherein the fines recycled resin comprises a melt index (as determined by ASTM D-1238, 190°C with a 2.16 kg load) of about 0.1 g / 10 min to about 20 g / 10 min.

18. The method of claim 13, wherein the plurality of polymeric fines comprises polypropylene fines.

19. The method of claim 18, wherein the PIR resin comprises polypropylene.

0. The method of claim 18, wherein the fines recycled resin comprises a melt index (as determined by ASTM D-1238, 190°C with a 2.16 kg load) of about 0.1 g / 10 min to about 20 g / 10 min.