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    HIGH PRESSURE POLYMERIZATION PROCESS, POLYMER BASED ON ETHYLENE, COMPOSITION AND ARTICLE The invention provides a high pressure polymerization process to form an ethylene-based polymer, the process comprising at least the following steps: feeding ethylene to a first reaction zone and to one or more subsequent reaction zones, and for each subsequent reaction zone receiving fresh ethylene, the ratio, Rn (n = reaction zone number, n> 1), of the? mass fraction of fresh ethylene fed to the first reaction zone (RZ1)? to the ? mass fraction of fresh ethylene fed to the umpteenth reaction zone (RZn)? is (Rn = RZ1 / RZn) greater than 1, or is from 1 to 20, or is from 0 to 0.30, and the? total amount of ethylene fed to the polymerization process? it is derived from at least one stream of fresh ethylene and at least one stream of recycled ethylene, and the at least one stream of recycled ethylene comprises at least one chain transfer agent and / or comprises more than, or equal to, 1 % by weight, based on the total amount of components in the recycled ethylene chain, of one or more components other than (...).
    公开号:BR112014009303B1
    申请号:R112014009303-2
    申请日:2012-10-10
    公开日:2021-02-02
    发明作者:Werner Zschoch；Otto J. Berbee；Cornelis J. Hosman
    申请人:Dow Global Technologies Llc；
    IPC主号:
    专利说明:

    Prior art
    [001] Ethylene-based polymers polymerized via free radical, high pressure (eg LDPE) are generally made in a tubular reactor, or in an autoclave reactor, or sometimes in a combination of these two reactors. In these polymerizations, a chain transfer agent (CTA) is used to regulate the molecular characteristic of the polymeric product. It is known that preferentially feeding “compensation chain transfer agent” (“make up CTA”) to the (previous) ethylene feed stream or to a lateral ethylene feed stream will respectively narrow or expand the molecular weight distribution ( MWD) of the polymeric product. Due to the low level of conversion of commonly used chain transfer agents (CTAs), a significant portion of the CTA added to the reactor is recycled back to polymerization through recycling systems, and the recycled chain transfer agent (CTA) is recycled. evenly distributed to all ethylene feeds to the reactor. “Compensation CTA” is added to the reactor supply currents to maintain the correct level of CTA in the polymerization, necessary to control the melting index of the product. The amount of “netting chain transfer agent flow”, which depends on the level of chain transfer agent conversion in the reactor and other losses, such as purging, the residual chain transfer agent in the product, and / or condensation in the recycling and compressor sections, typically ranges from 1 to 20 percent of the total amount of chain transfer agent added to the polymerization. The feed location of the “netting chain transfer agent” can be used to vary the “chain transfer agent (CTA) concentration ratio in the previous ethylene stream” versus the “ chain (CTA) in the side feed chain (s) ”. “Fresh ethylene” is added to the reactor to replenish converted and lost ethylene (via purge, etc.). Typically, fresh ethylene is added through the suction currents (at the inlet) of the Hyper compressor (secondary) with or with the aid of a Booster and / or Primary compressor. Conventional methods of feeding CTA using a Booster or Primary compressor result in minimal variation in the concentration of chain transfer agent (CTA) in the reactor feed streams, and these variations are especially limited with chain transfer agents (CTAs) of low reactivity (for example, see publication of US patent application no 2003/0114607).
    [002] There is a need for new polymerization processes, whereby the concentrations of CTA in the reactor can be varied widely and regardless of the level of “chain transfer agent (CTA) compensation” in the process. Such a process will significantly increase the range of molecular weight distributions (MWDs) and / or increase the range of melt resistances, at a given melt index, for the final polymeric products.
    [003] U.S. Patent No. 3,334,081 discloses a continuous process for the production of solid ethylene polymers, as carried out in a tubular reactor, whereby the polymer is obtained at a higher conversion rate. In one embodiment, the process comprises introducing a polymerizable ethylene reaction mixture into the tubular reactor in at least two separate streams, the first stream being injected into the tubular reactor at the inlet end of the tubular reactor, and the subsequent side streams being injected into the reactor tubular in lateral locations along the tubular reactor. The first stream is a mixture of ethylene and a chain transfer agent, selected from the group consisting of a) a saturated alcohol, b) a saturated aliphatic ketone, c) a saturated aliphatic aldehyde, and d) an alpha olefin. The subsequent side stream injected into the tubular reactor is a mixture of ethylene and the chain transfer agents, as defined above.
    [004] US patent No. 3,702,845 discloses the polymerization of ethylene in the presence of organic peroxides and oxygen, as polymerization initiators of free radicals, and in the presence of polymerization modifiers, in a tubular reactor having two successive reaction zones , to form ethylene homopolymers. A mixture of ethylene, polymerization initiator and polymerization modifier is introduced continuously at the beginning of each reaction zone. Ethylene homopolymers are reported to have broad molecular weight distributions, and are practically free of very high molecular weight constituents. See also U.S. Patent No. 3,657,212.
    [005] US patent No. 3,917,577 discloses a process for the continuous polymerization of ethylene, in the presence of a polymerization initiator and a polymerization regulator, in a tubular reactor having two or three successive reaction zones, to form homopolymers of ethylene. A mixture of ethylene, polymerization initiator and polymerization regulator is introduced continuously at the beginning of each reaction zone.
    [006] U.S. Patent Application Publication No. 2003/0114607 discloses tubular reactor equipment and processes for the production of polymers, using chain transfer agents and multiple monomer feeds. The equipment and methods are disclosed as decoupling or reducing the dependence between monomer concentration and chain transfer agent concentration.
    [007] U.S. Patent No. 6,569,962 discloses the polymerization of ethylene in a tubular reactor in the presence of free radical forming initiators, oxygen under these, and chain transfer agents of which at least one comprises an aldehyde structure. Chemokinetic characteristics of reactive feed materials are coupled with the fluidly relevant characteristics of the tubular reactor, to reduce interfering side reactions, especially polar-inductive substitution effects.
    [008] DD 276 598 A3 (English translation) discloses a process to adjust and regulate the inlet gas streams in multi-zone tubular reactors with at least two lateral inlet streams, for the production of ethylene polymers, by mass polymerization via free radical, and in the presence of 10 to 50 ppm of oxygen, as a polymerization initiator. It is also disclosed a purge then two steps of the reaction mixture in an intermediate pressure product separator, and a low pressure product separator, and a polymer separation, and returning the unreacted reaction gas to the cycle. A chain regulator and fresh ethylene are added to the low pressure return gas. The resulting gas stream is divided into two gas streams, at a ratio of 2: 1 to 1: 4, and to one of the gas streams is added oxygen, in an amount of 50 to 500 ppm, and the two streams of gas are separately compressed to intermediate pressure.
    [009] Additional polymerizations and / or resins are described in the following: U.S. 3,654,254; DDR 120200; GB 934444; and Kim et al., Molecular Weight Distribution in Low-Density Polyethylene Polymerization; Impact of Scission Mechanisms in the Case of a Tubular Reactor, Chemical Engineering Science, 59, 2004, 2039-2052.
    [0010] Conventional processes in the art are very limited in terms of making polymeric products with a wide range of molecular distributions and a wide range of melt resistances at a given melt index. It is noted that products with narrow MWD are typically made at reduced polymerization temperatures and, therefore, reduced conversion levels. As discussed above, there is a need for new polymerization processes, whereby the concentration of chain transfer agent in the reactor can be varied widely, and regardless of the level of "compensating chain transfer agent (CTA)" in the process. There is an additional need for such processes that can be used to form ethylene-based polymers with a wide range of molecular weight distributions (MWDs) and / or a wide range of melt resistances at a given melt index. There is also a need to produce products with narrow MWD at higher conversion levels. These needs were met by the following invention. summary
    [0011] The invention provides a high pressure polymerization process to form an ethylene-based polymer, the process comprising at least the following steps: feeding ethylene to a first reaction zone and to one or more subsequent reaction zones, and being that for each subsequent reaction zone receiving fresh ethylene, the ratio, Rn (n = reaction zone number, n> 1), of the “mass fraction of fresh ethylene fed to the first reaction zone (RZ1)” for the “Mass fraction of fresh ethylene fed to the umpteenth reaction zone (RZn)” is (Rn = RZ1 / RZn) greater than 1, or is from 1 to 20, or is from 0 to 0.30, and the “ total amount of ethylene fed to the polymerization process ”derives from at least one stream of fresh ethylene and at least one stream of recycled ethylene, and the at least one stream of recycled ethylene comprises at least one chain transfer agent and / or comprises more than, or equal to, 1% by weight, based on the total quantity components in the recycled ethylene chain, one or more components other than ethylene and / or chain transfer agent (CTAs); and the inlet current to each reaction zone comprises less than, or equal to, 5 ppm by weight of oxygen, based on the total weight of mass flows fed to the reaction zone.
    [0012] The invention also provides a process for forming an ethylene-based polymer, the process comprising the following steps: feeding ethylene to a first reaction zone and to one or more subsequent reaction zones, and 100 percent by weight of the total amount of fresh ethylene fed to the polymerization process is fed to the first reaction zone, and the “total amount of ethylene fed to the polymerization process” is derived from at least one stream of fresh ethylene and at least one stream of ethylene recycled, and the at least one recycled ethylene stream comprises at least one chain transfer agent and / or comprises more than, or equal to, 1% by weight, based on the total amount of components in the recycled ethylene stream , of one or more components other than ethylene and / or chain transfer agent (CTAs); and the inlet current to each reaction zone comprises less than, or equal to, 5 ppm by weight of oxygen, based on the total weight of mass flows fed to the reaction zone. Description of the drawings
    [0013] Figure 1 shows a polymerization flow scheme for a comparative polymerization process;
    [0014] Figure 2 shows a polymerization flow scheme for an inventive polymerization process;
    [0015] Figure 3 shows a polymerization flow scheme for a comparative polymerization process, showing a standard line up to a Primary compressor and a Booster compressor;
    [0016] Figure 4 shows a polymerization flow scheme for an inventive polymerization process, showing all Primary capacity to a previous stream;
    [0017] Figure 5 shows a polymerization flow scheme for an inventive polymerization process, showing all the Primary capacity to a side chain;
    [0018] Figure 6 shows a polymerization flow scheme for an inventive polymerization process, showing a line-up of the Booster to Primary A, alignment of Primary A to a High Pressure Recycling, and a alignment to Primary B;
    [0019] Figure 7 shows a polymerization flow scheme for an inventive polymerization process, showing an alignment of Primer B for a previous stream, and an alignment of the Booster compressor for High Pressure Recycling;
    [0020] Figure 8 shows “corrected melt strength” as a log function (Z1 / Z2);
    [0021] Figure 9 shows molecular weight distribution (Mw (abs) / Mn (conv)) as a function of log (Z1 / Z2);
    [0022] Figure 10 shows the film brightness as a function of log (Z1 / Z2); and
    [0023] Figure 11 shows the clouding of the film as a function of log (Z1 / Z2).
    [0024] In the polymerization flow schemes, “HPS” refers to the “High Pressure Separator”, and LPS refers to the Low Pressure Separator. Detailed Description
    [0025] As discussed above, in a first aspect, the invention provides a high pressure polymerization process to form an ethylene-based polymer, the process comprising at least the following steps: feeding ethylene to a first reaction zone and a or more subsequent reaction zones, and for each subsequent reaction zone receiving fresh ethylene, the ratio, Rn (n = reaction zone number, n> 1), of the “mass fraction of fresh ethylene fed to the first reaction zone (RZ1) ”for the“ mass fraction of fresh ethylene fed to the umpteenth reaction zone (RZn) ”is (Rn = RZ1 / RZn) greater than 1, or is from 1 to 20, or is from 0 to 0.30, and the “total amount of ethylene fed to the polymerization process” is derived from at least one stream of fresh ethylene and at least one stream of recycled ethylene, and the at least one stream of recycled ethylene comprises at least least one chain transfer agent and / or comprises more than, or equal to, 1% by weight, based on the total amount of components in the recycled ethylene chain, of one or more components other than ethylene and / or chain transfer agent (CTAs); and the inlet current to each reaction zone comprises less than, or equal to, 5 ppm by weight of oxygen, based on the total weight of mass flows fed to the reaction zone.
    [0026] An inventive process may comprise a combination of two or more embodiments as described here.
    [0027] In one embodiment, Rn is greater than 1.
    [0028] In one embodiment, Rn is zero.
    [0029] In one embodiment, Rn is 0 to 0.25, or 0 to 20.
    [0030] In one embodiment, Rn is 0 to 0.15 or 0 to 0.10.
    [0031] In one embodiment, when none (0%) fresh ethylene is fed to the first reaction zone, "the amount of ethylene fed to the first feed zone" will derive only from at least one stream of recycled ethylene.
    [0032] In one embodiment, the “total amount of ethylene fed into the polymerization process” is derived from a stream of fresh ethylene and at least one stream of recycled ethylene, and the at least one stream of recycled material comprises at least one chain transfer, and when, when none (0%) fresh ethylene is fed to the first reactor zone, then the “amount of ethylene fed to the first reaction zone” derives only from at least one recycled ethylene stream.
    [0033] In one embodiment, from “greater than 0” to 100 percent of the total amount of fresh ethylene fed to the polymerization process, it is (are) fed to the first reaction zone and / or to a reaction zone sequential. In a further embodiment, the first reaction zone is a tubular reaction zone.
    [0034] In one embodiment, 10 to 90, or 20 to 80, or 30 to 70, weight percent of the total amount of fresh ethylene fed to the polymerization process, is fed to the first reaction zone and / or to a sequential reaction zone. In a further embodiment, the first reaction zone is a tubular reaction zone.
    [0035] In a second aspect, the invention also provides a process for forming an ethylene-based polymer, the process comprising the following steps: feeding ethylene to a first reaction zone and to one or more subsequent reaction zones, and being 100 percent by weight of the total amount of fresh ethylene fed to the polymerization process is fed to the first reaction zone, and the “total amount of ethylene fed to the polymerization process” is derived from at least one stream of fresh ethylene and at least at least one stream of recycled ethylene, and the at least one stream of recycled ethylene comprises at least one chain transfer agent and / or comprises more than, or equal to, 1% by weight, based on the total amount of components in the recycled ethylene stream, one or more components other than ethylene and / or chain transfer agent (CTAs); and
    [0036] being that the input current to each reaction zone comprises less than, or equal to, 5 ppm in weight of oxygen, based on the total weight of mass flows fed to the reaction zone.
    [0037] An inventive process may comprise a combination of two or more embodiments as described here.
    [0038] The following embodiments apply to both the first and second aspects of the invention.
    [0039] In one embodiment, the at least one stream of recycled ethylene comprises at least one chain transfer agent.
    [0040] In one embodiment, at least one recycled ethylene stream comprises more than, or equal to, 1% by weight, based on the total amount of components in the recycled ethylene stream, of one or more recycled ethylene components, of one or more components other than ethylene and / or chain transfer agent (CTAs).
    [0041] In one embodiment, the at least one recycled ethylene stream comprises at least one chain transfer agent and comprises more than, or equal to, 1% by weight, based on the total amount of components in the recycled ethylene stream , one or more components of recycled ethylene, one or more components other than ethylene and / or chain transfer agent (CTAs).
    [0042] In one embodiment, the process comprises at least one Primary compressor and at least one Booster compressor.
    [0043] In one embodiment, the ethylene stream from the Booster compressor is fed to only one Primary compressor stream, and then the Primary compressor has at least two separate compression streams.
    [0044] In one embodiment, the ethylene stream from the Booster compressor is fed only to a compression flow from the Primary compressor, and the Primary compressor has at least two separate compression flows.
    [0045] In one embodiment, the first reaction zone is a tubular reaction zone.
    [0046] In one embodiment, each reaction zone is a tubular reaction zone.
    [0047] In one embodiment, the first reaction zone is an autoclave reaction zone.
    [0048] In one embodiment, the "total amount of ethylene fed into the polymerization process" derives from a stream of fresh ethylene and at least one stream of recycled ethylene, and the at least one stream of recycled ethylene comprises at least one chain transfer agent.
    [0049] In one embodiment, at least one stream of recycled ethylene is fed only to an incoming feed stream or only to a side feed stream.
    [0050] In one embodiment, the first reaction zone is a tubular reaction zone.
    [0051] In one embodiment, the input feed of each reaction zone comprises less than, or equal to, 3 or less than, or equal to, 2, or less than, or equal to 1, ppm by weight of oxygen, based on the total weight of mass flows fed to the reaction zone.
    [0052] In one embodiment, fresh ethylene does not contain any other chain transfer agent other than one or more residual compounds originating from the ethylene production / fractionation process.
    [0053] In one embodiment, the polymerization process operates without “injected” CTA, and with only “impurities” CTA compound (s) from ethylene-rich feed stream (s).
    [0054] In one embodiment, the process comprises a Primary compressor.
    [0055] In one embodiment, the ethylene-based polymer is a polyethylene homopolymer.
    [0056] In one embodiment, the ethylene-based polymer is an ethylene-based interpolymer comprising at least one comonomer.
    [0057] In one embodiment, each feed at each reaction zone contains the same system as the chain transfer agent (CTA). In a further embodiment, the chain transfer agent (CTA) system for each feed contains a single chain transfer agent (CTA).
    [0058] In one embodiment, at least one of the feeds to at least one of the reaction zones contains a chain transfer agent system that is different from at least one of the CTA system (s) for at least one another reaction zone.
    [0059] In one embodiment, at least one of the feeds to at least one of the reaction zones contains a CTA that is different from at least one of the chain transfer agents of the other reaction zones.
    [0060] In one embodiment, each chain transfer agent (CTA) is independently selected from an olefin, an aldehyde, a ketone, an alcohol, a saturated hydrocarbon, an ether, a thiol, a phosphine, an amino, an amine , an amide, an ester, or an isocyanate.
    [0061] In one embodiment, the maximum polymerization temperature in each reaction zone is, independently, greater than, or equal to, 100oC, and the inlet pressure in each reaction zone is, independently, greater than, or equal to , 100 MPa.
    [0062] In one embodiment, each of the polymerization conditions in the reaction zones, independently, comprises an adjusted temperature of less than 400oC, and an inlet pressure of less than 1000 MPa, or less than 500 MPa.
    [0063] In one embodiment, the maximum polymerization temperature in each reaction zone is, independently, from 100 to 400oC.
    [0064] An inventive process may comprise a combination of two or more of the embodiments as described here.
    [0065] The invention also provides an ethylene-based polymer made by an inventive process.
    [0066] In one embodiment, the ethylene-based polymer is a polyethylene homopolymer.
    [0067] In one embodiment, the ethylene-based polymer is an ethylene-based interpolymer.
    [0068] In one embodiment, the ethylene-based polymer has a density of 0.910 to 0.940 g / cm3.
    [0069] In one embodiment, the ethylene-based polymer has a melt index of 0.1 to 20 g / 10 min.
    [0070] In one embodiment, the ethylene-based polymer has a density of 0.910 to 0.940 g / cm3 and a melt index of 0.1 to 20 g / 10 min.
    [0071] An inventive polymer may comprise a combination of two or more embodiments as described here.
    [0072] The invention also provides a composition comprising an inventive ethylene-based polymer.
    [0073] In one embodiment, the composition additionally comprises another polymer based on ethylene.
    [0074] The inventive composition may comprise a combination of two or more embodiments as described here.
    [0075] The invention also provides an article comprising at least one component formed from an inventive composition. In one embodiment, the article is an extrusion coating resin. In another embodiment, the article is a film. In another embodiment, the article is an insulating material and / or a protective layer around a metal wire. In another embodiment, the article is a foam.
    [0076] An inventive article may comprise the combination of two or more combinations as described here. Polymerizations
    [0077] For a polymerization process initiated by free radical, high pressure, two basic types of reactors are known. The first type is a stirred autoclave vessel with one or more reaction zones (autoclave reactor). The second type is a jacketed tube reactor, whose tube has two or more reaction zones (the tubular reactor). The high pressure process of the present invention to produce polyethylene homo and interpolymers (for example, copolymers) can be carried out in a tubular and / or autoclave reactor, each having two reaction zones. For example, one or more tubular reactors (in series or in parallel); one or more tubular reactors and one or more autoclave reactors (in series or in parallel); one or more autoclave reactors (in series or in parallel); and one or more autoclave reactors and one or more tubular reactors (in series or in parallel). In one embodiment, polymerization is carried out in one or more tubular reactors (in series or in parallel).
    [0078] The temperature in each reaction zone of the process is typically from 100 to 400oC, more preferably from 120 to 360oC, and even more typically from 140 to 340oC. Inlet pressure (pressure can be measured using a pressure transducer located in the supply line at the inlet) in each reaction zone of the process is typically 100 to 500 MPa, more typically 120 to 400 MPa, and even more typically from 150 to 350 MPa. Examples of suitable reactor systems are described in U.S. Patent Application Publication No. 2003/0114607 and DDR 276 598 A3. Commercial high pressure polymerization processes are typically equipped with recycling systems, in order to maximize the conversion of the incoming ethylene into polymer, and to reduce the compression energy. High pressure recycling typically operates at inlet pressures from 50 to 600 bar, more typically from 120 to 500 bar and even more typically from 200 to 400 bar. Initiators
    [0079] The process of the present invention is a free radical polymerization process. Free radical-generating compounds include, but are not limited to, organic peroxides, such as peresters, percetals, peroxide ketones and percarbonates, di-butyl peroxide, cumila perneodecanoate, and ter-amyl perpivalate. Other suitable initiators include azodicarboxylic esters, azodicarboxylic dinitriles, and 1,1,2,2-tetramethyleneethane derivatives. These organic peroxy initiators can be used in conventional amounts from 0.005 to 0.2 weight percent, based on the weight of polymerizable monomers. Peroxides are typically injected as solutions diluted in a suitable solvent, for example, in a hydrocarbon solvent.
    [0080] In one embodiment, an initiator is added to at least one polymerization reaction zone, and the initiator has a "half-life temperature in one second" greater than 255oC, preferably greater than 260oC. In a further embodiment, such primers are used at a peak polymerization temperature of 320oC to 350oC. In a further embodiment, the initiator comprises at least one peroxide group incorporated into an annular structure.
    [0081] Examples of such initiators include, but are not limited to, TRIGONOX 301 (3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonaane) and TRIGONOX 311 (3.3, 5,7,7-pentamethyl- 1,2,4-trioxepano), both commercially available from Akzo Nobel, and HMCH-4-AL (3,3,6,6,9,9-hexamethyl-1,2,4 , 5-teroxonane) commercially available from United Inititators. See also international publications in WO 02/14379 and WO01 / 68723. Chain Transfer Agents (CTA)
    [0082] Chain transfer agents or telogens are used to control the melt index in a polymerization process. Chain transfer involves terminating growing polymer chains, thus limiting the final molecular weight of the polymeric material. A chain transfer agent is typically a component (for example, an organic molecule) capable of transferring a hydrogen atom to a growing polymer molecule containing a radical, by which a radical is formed in the chain transfer agent, which you can then start a new polymer chain. These agents can be of many different types, from saturated hydrocarbons, or unsaturated hydrocarbons, to aldehydes, ketones, or alcohols. By controlling the concentration of the selected chain transfer agent, one can control the length of the polymeric chains, and hence the molecular weight, for example, the numerical average molecular weight, Mn. The melt flow rate (MFI or I2) of a polymer, which is related to Mn, is controlled in the same way.
    The chain transfer agents in the process of this invention include, but are not limited to, aliphatic and olefinic hydrocarbons, such as pentane, hexane, cyclohexane, propene, pentene, or hexane; ketones, such as acetone, diethyl ketone or diamyl ketone; aldehydes, such as formaldehyde or acetic aldehyde; and alcohols of saturated aliphatic aldehydes such as methanol, ethanol, propanol or butanol.
    [0084] Comonomers such as vinyl acetate, alkyl acrylates, etc., may also exhibit chain transfer activity. Copolymers made with high levels of these comonomers are typically made with low levels, or none, of the additional chain transfer agent (CTA). The distribution of fresh ethylene and recycled ethylene containing unconverted comonomer, such as vinyl acetate, could have a similar effect on MWD, as described here. Polymers
    [0085] In one embodiment, the ethylene-based polymers of this invention have a density of 0.910 to 0.940, more typically 0.912 to 0.940 and even more typically 0.915 to 0.935, grams per cubic centimeter (g / cm3). In one embodiment, the ethylene-based polymers of this invention have a typical melting index (I2) of 0.1 to 100, more typically of 0.15 to 50, and even more typically of 0.2 to 20 grams for 10 minutes (g / 10 min) at 190 ° C / 2.16 kg. In one embodiment, the ethylene-based polymers of this invention have a typical Mw / Mn of 3 to 20, or 3.5 to 16, or 4 to 14. In one embodiment, the ethylene-based polymers of this invention have a resistance melt from 0.5 to 40, or from 1 to 30 centiNewtons (cN). In one embodiment, the ethylene-based polymers of this invention have two or more of these properties of density, melt index, Mw / Mn and melt strength.
    [0086] Ethylene-based polymers include LDPE homopolymer, and high-pressure copolymers, including ethylene / vinyl acetate (EVA), ethylene ethyl acrylate (EEA), ethylene butyl acrylate (EBA), ethylene acrylic acid (EAA) , ethylene vinyl silane (EVS), ethylene vinyl trimethyl silane (EVTMS), and other copolymers made with "silane-containing" comonomers made with dienes (eg ENB) or polyenes, and ethylene carbon monoxide (ECO). Other comonomers are described in Ehrlich, P .; Mortimer, G.A .; Adv. Polymer Science: Fundamentals of Free-Radical Polymerization of Ethylene; Vol. 7, pages 386-448 (1970). Additions
    [0087] An inventive composition may comprise at least one additive. Suitable additives include, but are not limited to, fillers, antioxidants and other stabilizers, colorants, extenders, crosslinkers, blowing agents, and plasticizers. In addition, other natural and synthetic polymers, including other polymers that are made according to the inventive process, and polymers made by other processes, may be added to an inventive composition. Mixtures
    [0088] The inventive polymers may be mixed with one or more other polymers, such as, but not limited to, linear low density polyethylene (LLDPE); copolymers of ethylene with one or more alpha-olefins, such as, but not limited to, propylene, butene-1, 1-pentene, 4-methylpentene-1, pentene-1, hexene-1, and octene-1; high density polyethylene (HDPE), such as, for example, HDPE grades 940-970 commercially available from The Dow Chemical Company. The amount of inventive polymer in the mixture can vary widely, but it is typically 10 to 90, or 15 to 85, or 20 to 80, percent by weight, based on the weight of the polymers in the mixture. Mixtures of LDPE (inventive) / LLDPE typically provide good optical properties, and / or are useful in the preparation of laminations, and / or are useful in applications such as films, extrusion coatings, foams, and wires and cables. applications
    [0089] An inventive composition may be employed in a variety of conventional thermoplastic fabrication processes to produce useful articles, including extrusion coatings; films; and molded articles, such as blow-molded, injection-molded, or rotational molded articles; foams; wires and cables, fibers and woven and non-woven fabrics. Definitions
    [0090] Unless otherwise stated, implicit in context, or customary in the art, all parts and percentages are by weight, and all test methods were current with respect to the date of filing of this disclosure. For the purposes of United States patent practice, the contents of any referenced patent, patent application or publication (or its equivalent US version) are thus incorporated by reference especially with respect to the disclosure of definitions (to the extent that they are not inconsistent) with any definitions in this disclosure) and general knowledge of the technique.
    [0091] The term "high pressure polymerization process", as used here, refers to a polymerization process via free radical carried out at an elevated pressure of at least 100 MPa (1000 bar).
    [0092] The phrase “total amount of fresh ethylene fed to the polymerization process”, as used here, refers to the mass sum of feed (s) of fresh ethylene fed to the “n” reaction zones.
    [0093] The term "fresh ethylene", as used here, refers to ethylene provided from an external source (s) and not from an internal recycled ethylene source (s). Fresh ethylene is used as the "compensating ethylene" required to compensate for the ethylene consumed by the polymerization or lost by, for example, purging the process and residual ethylene in the polymer. Fresh ethylene is typically produced and supplied with a high purity of 99.8% w / w or more, based on the total weight of the fresh ethylene supply. The biggest impurities are methane and ethane. A fresh ethylene feed stream contains only fresh ethylene as the ethylene component.
    [0094] The phrase “total amount of ethylene fed to the polymerization process”, as used here, refers to the mass sum of all feed streams rich in ethylene to the reactor that consist of ethylene as the major component, typically greater than 90% w / w, and typically greater than 96% w / w, based on the total weight of the feed, which includes, in addition to ethylene, components other than ethylene (components other than ethylene), such as, for example, methane , ethane, solvent, chain transfer agent (CTA), and / or peroxide dissociation products.
    [0095] The term "ethylene-rich feed stream", as used here, refers to a feed stream comprising a major amount of ethylene, based on the weight of the feed stream; for example, a fresh ethylene feed stream or recycled ethylene feed stream. Due to the presence of non-ethylene components (eg, methane, ethane, etc.) or the addition, or use, of other components (chain transfer agent (CTA), peroxide, decomposition components, solvent, etc.) , the concentration of ethylene in fresh and recycled ethylene will typically be about 99.8% w / w and about 97% w / w, respectively, based on the weight of the feed. In the case of low reactivity comonomers, such as vinyl acetate, the ethylene concentration may be further reduced, and may be as low as 60 weight percent.
    [0096] The term "recycled ethylene", as used here, refers to ethylene that is removed from the polymer in the high pressure and low pressure separators, and the recycled ethylene comprises ethylene not converted in the reactor. A feed stream of recycled ethylene comprises recycled ethylene.
    [0097] The term "mass fraction", as used here, refers to the ratio of the mass of a component in a mixture to the total mass of the mixture. The mass fraction can be determined by calculating the ratios between mass quantities or mass flows.
    [0098] The phrase “mass fraction of fresh ethylene fed to the first reactor zone (RZ1)”, as used here, refers to the amount of fresh ethylene fed to the first reactor zone divided by the amount of total ethylene fed to the first reaction zone.
    [0099] The phrase “mass fraction of fresh ethylene fed to the umpteenth reactor zone (RZn)”, as used here, refers to the amount of fresh ethylene fed to the umpteenth reactor zone divided by the amount of total ethylene fed to the umpteenth reaction zone.
    [00100] The terms "input current" or "input current in the reaction zone", as used here, refer to the total mass flow at the entrance to a reaction zone, and consists of the mass flow transferred from the zone previous reaction plus optional ethylene-rich feed streams.
    [00101] The terms "side chain" or "side supply chain", as used here, refer to the ethylene-rich supply chain to sequential reaction zones.
    [00102] The term "previous input feed stream", as used here, refers to the ethylene rich feed stream fed to the first reaction zone.
    [00103] The term "reaction zone input supply current", as used here, refers to the ethylene-rich supply current fed to the reaction zone.
    [00104] The phrase “feeding to the umpteenth reaction zone”, as used here, refers to “total mass flow at the entrance of the umpteenth reaction zone” minus “mass flow from the (n-1) outlet th reaction zone ”.
    [00105] The term "reaction zone", as used here, refers to the reactor zone where the polymerization reaction is initiated or restarted by the addition of radicals or components that dissociate into, and / or generate, radicals. Typically, the reaction medium is heated and / or cooled by a thermal transfer medium flowing through the jacket around the reactor.
    [00106] The term "first reaction zone", as used here, refers to the reactor zone where the polymerization reaction is first initiated by the addition of radicals or components that dissociate into, and / or generate, radicals. The first reaction zone ends at the point where there is a new supply of fresh ethylene and / or recycled ethylene and / or radicals and / or components that dissociate into, and / or generate, radicals.
    [00107] The terms "subsequent reaction zone", or "sequential reaction zone", as used here, refer to a reaction zone that receives ethylene and polymer from a previous reaction zone, and where radicals and components, that dissociate into, and / or generate, radicals, are added to the entrance to the subsequent (or sequential) reaction zone. The subsequent (or sequential) reaction zone ends at the subsequent (or sequential) reaction zone. The subsequent (or sequential) reaction zone ends at the point where there is a new supply of fresh and / or recycled ethylene and / or radicals and / or components that dissociate into, and / or generate, radicals: however, the umpteenth Reaction zone ends at the position of a reactor system pressure control device. The number of subsequent (or sequential) reaction zones is (n-1), where n is the total number of reaction zones.
    [00108] The term "clearing chain transfer agent (CTA)", as used here, refers to the chain transfer agent supply chain needed to compensate for the converted chain transfer agent (CTA) and / or lost in the high pressure polymerization process, and is typically needed to control or change the melt index of the product.
    [00109] The terms "chain transfer agent (CTA) activity", or "chain transfer activity coefficient (Cs value)" as used here, refer to the ratio between the "chain transfer rate ”And the“ ethylene propagation rate ”. See Mortimer references.
    [00110] The Booster compressor is a device that compresses the following: a) the low pressure recycled material coming from the LPS (Low Pressure Separator), and b) optionally, the recycled compressor packing leaks (leaks) , each at the required level on the inlet side of the Primary compressor. This compression can occur in one or multiple compression stages, and can be combined with intermediate cooling. A Booster compressor may consist of a single or multiple compressor housings and may be combined with a Primary compressor housings (s).
    [00111] The Primary compressor is a compressor that compresses the following: a) fresh inlet ethylene, and / or b) low pressure recycled from the Booster compressor, and / or c) the leaks from the recycled compressor fill, each up to the required pressure level on the inlet side of the Hyper Compressor. This compression can occur in one or multiple compression stages, and can be combined with intermediate cooling. The Primary compressor may consist of single or multiple compressor housing (s).
    [00112] Hyper compressor, or Secondary compressor, is a device that compresses the following: a) ethylene from HPR (High Pressure Recycling) me / or b) from the Primary compressor, each at a pressure level required to feed the reactor at its inlet pressure set point. This compression can occur in one or in multiple compression stages, and can be combined with an intermediate cooling. The Hyper compressor comprises an alternative piston compressor, and may consist of single or multiple compressor housing (s).
    [00113] The term "separate compression streams", as used here, refers to ethylene feed streams that are kept separate in two or more streams through the Primary and / or Hyper compressors. During the compression steps, the ethylene feed streams can be kept separate through the compression cylinders operating in parallel, or recombined after each compression step.
    [00114] The term "polymer" refers to a compound prepared by polymerizing monomers, whether of the same or different types. Therefore, the generic term polymer encompasses the term homopolymer (which refers to polymers prepared from a single type of monomer with the understanding that trace amounts of impurities may be incorporated into the polymer structure), and the term “interpolymer” as defined below.
    [00115] The term "interpolymer" refers to polymers prepared by the polymerization of at least two different types of monomers. The generic term interpolymer includes copolymers (which refers to polymers prepared from two different types of monomers), and polymers prepared from more than two different types of monomers.
    [00116] The term "ethylene-based polymer" or "ethylene polymer" refers to a polymer that comprises a majority amount of polymerized ethylene, based on the weight of the polymer, and, optionally, may comprise at least one comonomer.
    [00117] The term "ethylene-based interpolymer" or "ethylene interpolymer" refers to an interpolymer that comprises a majority amount of polymerized ethylene, based on the weight of the interpolymer, and comprises at least one comonomer.
    [00118] The term "composition", as used here, includes a mixture of materials comprising the composition, as well as reaction products and decomposition products formed from the materials of the composition.
    [00119] The term "chain transfer agent (CTA) system" includes a single chain transfer agent, or a mixture of chain transfer agents (CTAs), added to the polymerization process, typically to control the index of fusion. A CTA system includes a component capable of transferring a hydrogen atom to a growing molecule containing a radical, so that the radical is formed in the molecule of the chain transfer agent, which can then initiate a new polymeric chain. The chain transfer agent (CTA) is also known as telogen or telomer. In a preferred embodiment of the invention, each chain transfer agent (CTA) system comprises a single chain transfer agent (CTA).
    [00120] The term “high pressure recycle inlet pressure (HPR)” refers to the pressure level in the high pressure separator (HPS). Test Methods
    [00121] Density: Samples for density measurement are prepared according to ASTM D 1928. Samples are pressed at 190oC and 30,000 psi for three minutes, and then at (21oC) and 207 MPa for one minute. Measurements are made within one hour of pressing the samples, using ASTM D792, Method B.
    [00122] Melting Index: The melting index, or I2, (grams / 10 minutes) is measured with ASTM D 1238, Condition 190oC / 2.16 kg. I10 is measured with ASTM D 1238, Condition 190oC / 10 kg.
    [00123] Melt Strength (MS): This is a measure of the extensional viscosity of polymer melts, and represents the maximum stress that can be applied to the melt, without breaking or tearing the melt. A capillary viscometer is used to extrude a polymer filament, and the filament is pulled by a pair of rollers until it breaks. The melt resistance (MS) was measured using a GOETTFERT RHEOTENS connected to an INSTRON capillary rheometer. The polymer was extruded through a capillary, at an aspect ratio (capillary length / capillary radius) of 30, and at a constant plunger speed. Hence, the polymer melt was subjected to a constant apparent wall shear rate. The extruded cast was subsequently stretched by a pair of knurled wheels having 19 mm radii, at a distance (H) from the capillary outlet. The rotational speed of the wheels was increased linearly over time, while the extraction force (F) was monitored. The melt strength was reported as the extraction force (cN) measured when the polymer filament broke. The following conditions were used in the measurement of melt strength: temperature 220oC, piston speed 0.2 mm / s, wheel acceleration 6 mm / s2, capillary radius 1 mm, capillary length 30 mm, cylinder radius 6 mm , wheel radius 19 mm, and distance (H) 100 mm.
    [00124] Triple Gel Permeation Chromatography Detector (TDGPC)
    [00125] The analysis of 3 High Temperature Det-GPC was performed in an Alliance GPCV2000 instrument (Waters Corp.) adjusted to 145oC. The flow rate for the GPC was 1 ml / min. The injection volume was 218.5 μL. The column set consisted of four Mixed-A columns (20 μm particles; 7.5 x 300 mm; Polymer Laboratories Ltd.)
    [00126] The detection was achieved using a Polymer ChAR IR4 detector, equipped with a CH sensor; a Wyatt Technology Dawn DSP MALS detector (Wyatt Technology Corp, Santa Barbara, CA, USA) equipped with a 30 mW argon ion laser operating at À = 488 nm; and a Waters tri-capillary viscosity detector. The MALS detector was calibrated by measuring the dispersion intensity of the TCB solvent. The normalization of the photodiodes was done by injecting SRM 1483, a high density polyethylene with a high average molecular weight (Mw) of 32,100 and polydispersity of 1.11. An increment of refractive index (Dn / Dc) of -0.104 mL / mg, for polyethylene in TCB, was used.
    [00127] The conventional GPC calibration was done with 20 narrow PS standards (Polymer Laboratories, Ltd.) with molecular weights in the range of 580-7,500,000 g / mol. The standard molecular weights of polystyrene were converted to molecular weights of polyethylene using
    where A = 0.39, B = 1. The value of A was determined using a HDPE reference, a linear polyethylene homopolymer with Mw of 115,000 g / mol. The HDPE reference material was also used to calibrate the IR detector and viscometer, assuming 100% mass recovery and an intrinsic viscosity of 1,873 dL / g. 1,2,4-Trichlorobenzene distilled “Baker Analyzed-grade” (JT Baker, Deventer, Netherlands) containing 200 ppm 2,6-di-ter-butyl-4-methylphenol (Merck, Hohenbrunn), Germany) used as a solvent for sample preparation, as well as for 3Det-GPC experiments. HDPE SRM 1483 was obtained from the US National Institute of Standards and Technology (Gaithersburg, MD, USA), LDPE solutions were prepared by dissolving the samples under gentle agitation for three hours at 160oC. The PS standards were dissolved under the same conditions for 30 minutes. The sample concentration for the 3 Det-GPC experiments was 1.5 mg / ml, and the polystyrene concentrations were 0.2 mg / ml.
    [00128] A MALS detector measures the scattered signal of polymers or particles in a sample under different angles θ. The basic light scattering equation (from M. Anderson, B. Wittgren, K.-G. Wahlund, Anal. Chem. 75, 4279 (2003)) can be written as:
    where Rθ is the surplus Rayleigh ratio, K is an optical constant, which is, among other things, dependent on the increment in the specific refractive index (Dn / Dc), c is the concentration of the solute, M is the molecular weight, Rg is the radius of rotation, and X is the wavelength of the incident light. The calculation of molecular weight and radius of rotation from light scattering data requires extrapolation at zero angle (see also PJ Wyatt, Anal. Chem. Acta 272, 1 (1993)). This is done by plotting (Kc / Ra) 1/2 as a function of sen2 (θ / 2) in the so-called Debye plot. The molecular weight can be calculated from the intersection with the ordinate, and the radius of rotation from the initial slope of the curve. The Zimm and Berry methods are used for all data. The second virus coefficient is assumed to be insignificant. The intrinsic viscosity numbers are calculated from both the viscosity signals and the concentration detector taking the ratio of the specific viscosity and the concentration to each elution slice. ASTRA 4.72 software (Wyatt Technology Corp.) is used to collect the signals from the IR detector, viscometer, and MALS detector. Data processing is done with internally generated Microsoft EXCEL macros.
    [00129] The calculated molecular weights, and molecular weight distributions are obtained using a light scattering constant derived from one or more of the aforementioned polyethylene standards and a refractive index concentration coefficient, dn / dc, of 0.104. Generally, the response of the mass detector and the light scattering constant should be determined from a linear pattern with a molecular weight greater than about 50,000 Daltons. Calibration of the viscometer can be obtained using the methods described by the manufacturer or, alternatively, using the published values of suitable linear standards, such as Standard Reference Materials (SRM) 1475a, 1482a, 1483, or 1484a. Chromatographic concentrations are assumed to be low enough to eliminate the introduction of 2nd viral coefficient effects (concentration effects on molecular weight). Blown Film Manufacturing: Conditions for blown film manufacturing are listed in table A. The thickness of the blown films was measured with a micrometer.
    Experimental
    [00130] In all examples of polymerization (comparative and inventive), propionic aldehyde was used as the chain transfer agent. Comparative Example A1
    [00131] The polymerization was carried out in a tubular reactor with three reaction zones. In each reaction zone, pressurized water was used to cool and / or heat the reaction medium, circulating this water through the reactor jacket. Each reaction zone had an entrance and an exit. Each input stream consisted of the output stream from the previous reaction zone and / or an ethylene-rich feed stream. Unconverted ethylene, and other gaseous components at the reactor outlet, were recycled through high pressure and low pressure recycles, and were compressed and distributed through the Booster, Primary and Hyper (Secondary) compressors according to the flow scheme 1 (see figure 1). Organic peroxides were fed to each reaction zone.
    [00132] After reaching the first peak temperature (maximum temperature) in reaction zone 1, the reaction medium was cooled with the aid of pressurized water. At the exit of reaction zone 1, the medium was additionally cooled by injecting a feed stream rich in fresh, cold (<120oC) ethylene (# 20), and the reaction was re-initiated by feeding an organic peroxide. This process was repeated at the end of the second reaction zone to allow for additional polymerization in the third reaction zone. The weight ratio of fresh ethylene feed streams to the three reaction zones was 1.00: 0.75: 0.25. The chain transfer agent at each reaction zone entrance originated from low pressure recycling and high pressure recycling flows (# 13 and # 15), as well as a chain transfer agent (CTA) stream of freshly injected netting # 7 and / or chain # 6. In this comparative example, the weight ratio between the "clearing chain transfer agent (CTA)" # 7 and # 6 streams was 1.00.
    [00133] The ethylene flux and chain transfer agent (CTA) distribution are described in tables 1A and 1B, while additional process conditions and properties of derived polymers, and film data, being given in tables 3A and 3B . The values of R2 and R3 are 0.44 each. The values of Z1 / Z2 and Z1 / Z3 are 1.24 each. Inventive Example A2
    [00134] The polymerization was carried out in a tubular reactor with three reaction zones, as discussed above. Unconverted ethylene, and other gaseous components at the reactor outlet, were recycled through the Booster compressor as high pressure recycles and low pressure recycles, and were compressed and distributed through the Primary and Hyper (Secondary) compressors according to scheme 2 (see figure 2).
    [00135] In each reaction zone, polymerization was initiated with organic peroxides. After reaching the first peak temperature in reaction zone 1, the reaction medium was cooled with the aid of pressurized water. At the exit of the first reaction zone, the reaction medium was additionally cooled by injecting a feed stream rich in fresh, cold ethylene (# 20), and the reaction was started again by feeding organic peroxide to the reaction zone. This process was repeated at the end of the second reaction zone, to allow for additional polymerization in the third reaction zone.
    [00136] The weight ratio of feed streams rich in fresh ethylene to the three reaction zones was 1.00: 0.75: 0.25. The chain transfer agent at each reaction zone inlet originated from low pressure recycling and high pressure recycling flows (# 13 and # 15), as well as a freshly compensating chain transfer agent chain injected # 7 and / or chain # 6. In this inventive example, the weight ratio between netting chain transfer agent (CTA) streams # 7 and # 6 was 0.98. The ethylene flow and chain transfer agent (CTA) distribution are described in tables 2A and 2B, while additional process conditions and derived polymer properties, and film data, are given in tables 3A and 3B. The values of R2 and R3 are 2.28 each. The values of Z1 / Z2 and Z1 / Z3 are 0.81 each. Comparative Example A0:
    [00137] The polymerization was carried out according to the description of comparative example A1 above, with the following modifications. In this comparative example, the weight ratio of clearing chain transfer agent (CTA) streams # 7 and # 6 was 2.19. The values of R2 and R3 were 0.44 each. The values of Z1 / Z2 and Z1 / Z3 were 1.29. Comparative Example B1
    [00138] Polymerization was carried out according to the description above for comparative example A1 with the following modifications. In this comparative example, the weight ratio of the compensating chain transfer agent (CTA) streams # 7 and # 6 is 0.95. The values of R2 and R3 are 0.44 each. The values of Z1 / Z2 and Z1 / Z3 are 1.35 each. Inventive Example B2:
    [00139] Polymerization was carried out according to the above description for inventive example A2 with the following modifications. In this inventive example, the weight ratio of the compensating chain transfer agent (CTA) streams # 7 and # 6 is 0.17. The values of R2 and R3 are 2.28 each. The values of Z1 / Z2 and Z1 / Z3 are 0.75 each. As discussed above, summaries of polymerization conditions are listed in tables 1A, 1B, 2A, 2B and 3A. The film properties and film data are listed in table 3B. Calculation of Clearing Chain Transfer Agent (CTA) Level
    [00140] Table 4A is used to calculate the levels of compensating chain transfer agent (CTA) in tables 1B and 2B (propionic aldehyde compensation level). Table 4 provides Cs values as measured by Mortimer (see references 1-5 noted below table 4A). The values in italics in bold are the calculated values of Cs based on the activation energy and the activation volume (Mortimer data). These Cs values are calculated under the average conditions of the tubular polymerizations. Table 4A: Cs Values
    1. G. Mortimer: Journal of Polymer Science: Part A-1; Chain Transfer in Ethylene Polymerization; vol 4, pgs. 881-900 (1966). 2. G. Mortimer: Journal of Polymer Science: Part A-1; Chain Transfer in Ethylene Polymerization, Part IV. Additional Study at 1369 atm and 130oC; vol 8, pgs. 15131523 (1970). 3. G. Mortimer: Journal of Polymer Science: Part A-1; Chain Transfer in Ethylene Polymerization, Part V. The Effect of Temperature; vol 8, pgs. 1535-1542 (1970). 4. G. Mortimer: Journal of Polymer Science: Part A-1; Chain Transfer in Ethylene Polymerization, Part V. The Effect of Pressure; vol 8, pgs. 1548-1542 (1970). 5. G. Mortimer: Journal of Polymer Science: Part A-1; Chain Transfer in Ethylene Polymerization, Part VII. Very reactive and depletable transfer agents; vol 10, pgs. 163-168 (1972). Chain Transfer Agent (CTA) Conversion and Losses
    [00141] Level of conversion of chain transfer agent (CTA) in reactor = conversion of Ethylene * Cs; and ethylene conversion level = 28.85%
    [00142] Level of conversion of chain transfer agent (CTA) into reactor: Propionic Aldehyde: 4.9%; and Acetone: 1.4%
    [00143] Additional losses of chain transfer agent are through purge gas (0.22%), the residual polymer chain transfer agent (CTA), and by condensation in the Booster compressor section. The last two losses are a function of the component's current pressure.
    [00144] These additional losses were calculated by ASPEN and total for: Propionic Aldehyde: 0.5%; and Acetone: 1%. ASPEN stands for AspenTech process simulation software (commercially available from AspenTech).
    [00145] The following process parameters were estimated with ASPEN: the distribution of the chain transfer agent (CTA) over high pressure and low pressure recycles, the chain transfer agent (CTA) lost as a residual in the polymer, and condensation of chain transfer agent in the Booster compressor, and condensation of the hydrocarbon solvent used as a peroxide diluent, in the Booster compressor.
    [00146] The estimate for the total loss per process passage (including conversion in the reactor) is given as: Propionic Aldehyde: 5.4%; and Acetone: 2.4%.
    [00147] Furthermore, ASPEN predicts that the concentration of propionic aldehyde in low pressure recycling (LPR), ie twice as high as the concentration of propionic aldehyde in high pressure recycling (HPR). Alternative Flow Schemes - Effects of Fresh Ethylene Distribution on Chain Transfer Agent (CTA) Distribution in the Reactor
    [00148] Tables 5-8 provide a comparison of the results of distribution of fresh ethylene and transfer agent (CTA) for different flow schemes shown in figures 1-7.
    [00149] Table 9 shows the distribution of non-ethylene components on the reactor supply currents. When non-ethylenic components typically consist of added components such as methane, ethane, chain transfer agent (CTA), solvent, etc., and / or formed components, such as peroxide dissociation products, such as, for example, ter -butanol, acetone and CO2. Due to the low purging rate and low conversions, these components will accumulate, and may cause the ethylene content to fall below 97% w / w. The accumulation of these impurities, found in the stream (s) of recycled ethylene, will affect the polymerization process by reducing the concentration of ethylene, and introducing components exhibiting chain transfer activity. The overall impact, the reduction in ethylene concentration and the chain transfer activity of some of the components, is similar to the result obtained using a chain transfer agent (CTA) system. Table 9 shows the impact of the distribution of fresh ethylene on the purity levels of 97% and 99.8% of recycled and fresh ethylene, respectively, on the ethylene content in the feed streams.




























    [00150] Table 10 lists the CTA activity ratio in extreme and uniform “CTA compensation” distributions for different Primary and / or Booster compressor configurations, using CTA with an eight percent weight compensation level, as determined by the “total hourly amount of CTA fed to the reactor” divided by the “total hourly amount of CTA fed to the reactor”. As seen in table 10, the Z1 / Zn ratio can be varied widely by different flow arrangements, and this variation can be further maximized by the distribution of the offsetting CTA. Table 10: Results of calculating the distribution of fresh ethylene and CTA for different flow schemes

    [00151] Table 11 shows the minimum and maximum Z1 / Z2 (= Z1 / Z3) ratios calculated for different distributions of CTAs with different levels of compensation (for flow scheme 3 and the combination of flow schemes 4 and 5; where "0" means not applied, and "X" means applied. For ranges in R values see table 10. Table 11

    [00152] As seen in table 11, only the distribution of CTA of compensation changes, the range of Z1 / Zn varies from “0.96 to 1.04” for a CTA with low level of compensation (2%) and varies from “0.72 to 1.38” for a CTA with a high level of compensation (16%). If only the distribution of fresh ethylene changes, the range of the Z1 / Zn ratio ranges from “0.55 to 1.83” to “0.60 to 1.67” for, respectively, CTAs with a low (2%) and high (16%) compensation levels. If both the distribution of fresh ethylene and the distribution of the “compensation CTA” changes, the range of the Z1 / Zn ratio ranges from “0.52 to 1.92” to “0.42 to 2.39”, respectively, for CTAs with low (2%) and high (16%) compensation levels. The data in Table 11 clearly shows that the invention provides for the following: a) a wide range of Z1 / Zn ratios even for low-activity CTAs; b) broader ranges of Z1 / Zn ratios when only fresh ethylene distribution is applied, compared to a “compensating Chain Transfer Agent (CTA) distribution” only; and c) unique Z1 / Zn ratios for polymerization systems equipped with an ethylene recycling system, when both a fresh ethylene distribution and a compensating “Chain Transfer Agent” (CTA) distribution are applied.
    [00153] Additionally, as seen in figures 8, the inventive polymerizations (see open circles) allow a polymer with melt resistance (MS) significantly higher at Z1 / Z2 ratios lower than 0.81 (log (0.81 ) = 0.09) and 0.75 (log (0.75) = 0.13), compared to comparative polymerizations (see closed circles), which formed polymers with lower melt resistances at Z1 / Z2 ratios more highs of 1.29, 1.24 and 1.35 (respectively, the log data is 0.11, 0.09 and 0.13). In addition, Z1 / Z2 ratios greater than 1.50 (log (1.5) = 0.18, (inventive examples from Table 10 and Table 11) can be used to form polymers with an additional reduction in melt strength. in figure 9, the inventive polymerizations (see open circles) allow a polymer with significantly wider MWD at lower Z1 / Z2 ratios of 0.81 and 0.75, compared to the comparative polymerizations (see closed circles), which formed polymers with narrower MWD at Z1 / Z2 ratios higher than 1.29, 1.24 and 1.35, in addition, Z1 / Z2 ratios higher than 1.50 (inventive examples in Table 10 and Table 11) can be used to form polymers with additionally narrowed MWD.
    [00154] As seen in figure 10, inventive polymerizations (see open circles) allow polymeric films with significantly lower film gloss at lower Z1 / Z2 ratios of 0.81 and 0.75, compared to comparative polymerizations ( see closed circles), which formed polymeric films with higher film brightness at higher Z1 / Z2 ratios of 1.29, 1.24 and 1.35. In addition, Z1 / Z2 ratios higher than 1.50 (inventive examples from table 10 and table 11) can be used to form polymeric films with an increase in film brightness. As seen in fig. 11, the inventive polymerizations (see open circles) allow polymeric films with significantly higher film turbidity at Z1 / Z2 rates as low as 0.81 to 0.75, compared with the comparative polymerizations (see closed circles), which formed polymeric films with significantly lower turbidity at higher Z1 / Z2 ratios of 1.29, 1.24 and 1.35. In addition, Z1 / Z2 ratios greater than 1.50 (inventive examples from table 10 and table 11) can be used to form films with an additional reduction in film clouding. As shown in figures 8-11, the Z1 / Zn ratio is important for modifying product properties, such as MWD, melt strength and film optics. The Z1 / Zn ratio can be varied by the value of Rn as shown in table 10.
    权利要求:
    Claims (9)
    [0001]
    1. High pressure polymerization process, to form a polymer based on ethylene, characterized by the fact that it comprises at least the following steps: - feeding ethylene in a first reaction zone and in one or more subsequent reaction zones, and being that for each subsequent reaction zone to that receiving fresh ethylene, the ratio, Rn (n = reaction zone number, n> 1), of the “mass fraction of fresh ethylene fed to the first reaction zone (RZ1)” for the “Mass fraction of fresh ethylene fed to the umpteenth reaction zone (RZn)” is (Rn = RZ1 / RZn) greater than 1 or is 0 to 0.25, and - with the “total amount of ethylene being fed to the process "polymerization stream" derives from at least one stream of fresh ethylene and at least one stream of recycled ethylene, and the at least one stream of recycled ethylene comprises at least one chain transfer agent and comprises more than, or equal to, 1% by weight, based on the total amount of components in the recycled ethylene stream, one or more non-ethylene components, including the chain transfer agent (CTA); and - the input current to each reaction zone comprises less than or equal to 5 ppm by weight of oxygen, based on the total weight of mass flows fed to the reaction zone.
    [0002]
    2. Process according to claim 1, characterized in that the process comprises at least one Primary compressor and at least one Booster compressor.
    [0003]
    3. Process according to claim 2, characterized in that the ethylene stream of the Booster compressor is fed only in a Primary compression flow, and the Primary compressor has at least two separate compression flows.
    [0004]
    4. Process, according to claim 1, characterized by the fact that Rn is greater than 1.
    [0005]
    5. Process, according to claim 1, characterized by the fact that Rn is zero.
    [0006]
    6. Process according to claim 1, characterized by the fact that the first reaction zone is a tubular reaction zone.
    [0007]
    7. Process according to claim 1, characterized in that 100 percent by weight of the total amount of fresh ethylene fed to the polymerization process is fed to the first reaction zone and / or to a sequential reaction zone.
    [0008]
    8. Process, according to claim 1, characterized by the fact that the process comprises only one Primary compressor.
    [0009]
    9. Process, according to claim 1, characterized by the fact that an initiator is added to at least one polymerization reaction zone, and the initiator has a “half-life temperature in one second” greater than 255oC.
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    法律状态:
    2018-03-27| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2019-10-01| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2020-08-25| B06A| Notification to applicant to reply to the report for non-patentability or inadequacy of the application [chapter 6.1 patent gazette]|
    2020-12-22| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-02-02| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 10/10/2012, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    US201161548996P| true| 2011-10-19|2011-10-19|
    US61/548,996|2011-10-19|
    PCT/US2012/059469|WO2013059042A1|2011-10-19|2012-10-10|Polymerization processes with fresh ethylene distributions for preparation of low density ethylene-based polymers|
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