Method for producing LDPE

Abstract

A process for producing low density polyethylene (LDPE) includes feeding ethylene into a front inlet and one or more side inlets of a high pressure reactor; and feeding a mixture of hydrocarbon-based molecules into the high pressure reactor, each hydrocarbon-based molecule comprising three or more carbon-carbon double bonds. At least 20% by weight of the total amount of ethylene fed to the high pressure reactor can be fed to the front inlet of the high pressure reactor; at least 20% by weight of the total amount of ethylene fed to the high pressure reactor can be fed to a first side inlet of the high pressure reactor; at least 40% by weight of the mixture of hydrocarbon-based molecules can be fed to the front inlet of the high pressure reactor; and the mixture of hydrocarbon-based molecules can be fed to the high pressure reactor downstream of at least one ultrahigh pressure compressor to produce the LDPE via free radical polymerization.

Description

Cross-reference to related applications

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 586,470, filed on September 29, 2023, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0002] Embodiments of this disclosure relate to methods for producing ethylene-based polymers, and more specifically, to the production of low-density polyethylene. Background Technology

[0003] High-pressure tubular reactors have been used industrially to produce low-density polyethylene (LDPE) products for over 40 years. The plug flow characteristics of a tubular reactor create gradients in temperature, pressure, and polymer / ethylene concentration along the reactor. Consequently, LDPE materials produced using tubular reactors typically have a narrower molecular weight distribution (“Mw / Mn”) and lower melt strength (“MS”) than conventionally produced LDPE. This limits the applicability of LDPE produced in tubular reactors in certain applications, such as extrusion coatings and blown films.

[0004] Known methods for altering the Mw / Mn and MS of LDPE materials include modifying reactor configuration, fine-tuning process conditions (pressure and temperature), modifying reactor configuration, and changing the concentration of modifiers (such as chain transfer agents (CTA)) along the reactor, thereby extending the product capacity of tubular reactors.

[0005] Through these efforts, materials suitable for extrusion coatings (with appropriate necking (NI) and stretching (DD)) have been successfully produced in tubular reactors. However, adverse effects on density, FDA extractability, and fumes have been observed.

[0006] One proposed solution is to use branching agents, which broaden the molecular weight distribution, thereby increasing melt strength under less extreme process conditions. Density capacity, FDA extractability, and extrusion coating properties can also be improved in this way.

[0007] However, the use of branching agents significantly increases raw material costs. Furthermore, high levels of unsaturated groups and unreacted branching agents can lead to high gel levels in the final product, thus increasing the amount of substandard products. During extrusion coating, products with high levels of unreacted branching agents tend to have increased fumes, undesirable tastes and odors, and edge instability. Summary of the Invention

[0008] It is necessary to reduce the concentration of branching agents required to achieve the desired molecular weight distribution, melt strength, and other polymer properties. Additionally, it is necessary to reduce the amount of unreacted branching agents in LDPE.

[0009] Embodiments of this disclosure address this need by providing a method in which the majority of the branching agent is fed to the front side of the reactor. Surprisingly, it has been found that, for a given branching agent concentration, introducing most (or even all) of the branching agent to the front side of the reactor, relative to introducing the branching agent to the sides of the reactor, produces polymers with improved melt strength and molecular weight distribution. Furthermore, specific configurations of the fresh ethylene feed have been found to potentially lead to improved melt strength and molecular weight distribution.

[0010] According to some embodiments, a method for producing low-density polyethylene (LDPE) may include feeding ethylene into the front inlet of a high-pressure reactor at a pressure of at least 1000 bar; feeding ethylene into one or more side inlets of the high-pressure reactor at a pressure of at least 1000 bar; and feeding a mixture of hydrocarbon-based molecules into the high-pressure reactor, each hydrocarbon-based molecule containing three or more carbon-carbon double bonds. At least 20% by weight of the total ethylene fed into the high-pressure reactor may be fed into the front inlet of the high-pressure reactor; at least 20% by weight of the total ethylene fed into the high-pressure reactor may be fed into the first side inlet of the high-pressure reactor; at least 40% by weight of the mixture of hydrocarbon-based molecules may be fed into the front inlet of the high-pressure reactor; and the mixture of hydrocarbon-based molecules may be fed into a high-pressure reactor downstream of at least one ultra-high-pressure compressor, thereby producing LDPE via free radical polymerization at a pressure of at least 1000 bar.

[0011] These and other embodiments are described in more detail in the Detailed Description. It should be understood that both the foregoing general description and the following detailed description present embodiments of the technology disclosed in this invention and are intended to provide an overview or framework for understanding the nature and features of the technology as claimed. Drawings are included to provide a further understanding of the technology disclosed in this invention, and these drawings are incorporated in and form a part of this specification. The drawings illustrate various embodiments and, together with the description, serve to explain the principles and operation of the technology disclosed in this invention. Furthermore, the drawings and description are intended to be illustrative only and are not intended to limit the scope of the claims in any way. Attached Figure Description

[0012] The following detailed description of specific embodiments of this disclosure is best understood in conjunction with the following drawings, in which similar reference numerals indicate similar structures and in the drawings:

[0013] Figure 1 This is a schematic diagram of a system for forming low-density polyethylene according to one embodiment described and disclosed herein.

[0014] Figure 2 It is a diagram showing the relationship between melt strength, branching agent concentration, and branching agent feed location.

[0015] Figure 3 This is a diagram illustrating GPC results for several polymers according to some embodiments of this disclosure.

[0016] For the purpose of simplifying the schematic diagrams and illustrations of the related figures, numerous valves, temperature sensors, electronic controllers, and other components well-known to and likely employed by those skilled in the art in certain chemical processing operations are not included. Furthermore, ancillary components commonly included in typical chemical processing operations, such as air supply systems, catalyst hoppers, and flue gas treatment systems, are not depicted. However, operating components (such as those described in this disclosure) may be added to the embodiments described in this disclosure.

[0017] It should be further noted that the arrows in the accompanying drawings refer to process streams. However, arrows can also refer equivalently to transfer lines used to transfer process streams between two or more system components. Additionally, arrows connected to system components define the inlet or outlet of each given system component. The direction of the arrows generally aligns with the primary direction of movement of the material contained within the physical transfer line represented by the arrow. Furthermore, arrows not connected to two or more system components represent product streams leaving the depicted system or system inlet streams entering the depicted system. Product streams may be further processed in an accompanying chemical processing system or may be commercialized as a final product. System inlet streams may be streams transferred from an accompanying chemical processing system or may be unprocessed raw material streams. Some arrows may indicate recycle streams, which are outflow streams from system components and are recycled back into the system. However, it should be understood that in some embodiments, any illustrated recycle stream may be replaced by a system inlet stream of the same material, and a portion of the recycle stream may leave the system as a system product.

[0018] Additionally, the arrows in the accompanying drawings may schematically depict process steps for transferring material streams from one system component to another. For example, an arrow pointing from one system component to another may indicate the "transfer" of effluent from one system component to another, which may include the "discharge" or "removal" of process stream contents from one system component and the "introduction" of the product stream contents into another system component. It should be understood that the arrows in the relevant drawings do not indicate necessary or essential steps.

[0019] It should be understood that, according to the embodiments presented in the relevant figures, the arrow between two system components may indicate that the material flow is unprocessed between the two system components. In other embodiments, the material flow represented by the arrow may have substantially the same composition throughout the transport process between the two system components. Furthermore, it should be understood that in one or more embodiments, the arrow may indicate that at least 75% by weight, at least 90% by weight, at least 95% by weight, at least 99% by weight, at least 99.9% by weight, or even 100% by weight of the material flow is transported between the system components. Therefore, in some embodiments, not all of the material flow represented by the arrow will be transported between the system components, such as when there is a side flow.

[0020] It should be understood that in the schematic flow diagrams of the relevant accompanying figures, the intersection of two or more lines indicates that two or more process streams are "mixed" or "merged". Mixing or merging can also include mixing by directly introducing the two streams into similar reactors, separation units, or other system components. For example, it should be understood that when two streams are depicted as being merged directly before entering a separation unit or reactor, in some embodiments these streams may be equivalently introduced into the separation unit or reactor and mixed in the reactor.

[0021] Reference will now be made in more detail to various embodiments, some of which are illustrated in the accompanying drawings. Where possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts. Detailed Implementation

[0022] The term "polymer" refers to a polymeric compound prepared by polymerizing monomers, whether of the same or different types. Therefore, the general term polymer encompasses the term "homopolymer," which is typically used to refer to a polymer prepared from only one type of monomer; and "copolymer," which refers to a polymer prepared from two or more different types of monomers.

[0023] "Polyethylene" or "ethylene-based polymer" should mean a polymer comprising more than 50% by weight of units derived from ethylene monomers. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more monomer types). Common forms of polyethylene known in the art include low-density polyethylene (LDPE); linear low-density polyethylene (LLDPE); ultra-low-density polyethylene (ULDPE); very low-density polyethylene (VLDPE); single-point catalytic linear low-density polyethylene, including both linear and substantially linear low-density resins (m-LLDPE); medium-density polyethylene (MDPE); and high-density polyethylene (HDPE).

[0024] The term "LDPE" can also be referred to as "high-pressure ethylene polymer" or "highly branched polyethylene," and is defined as meaning that the polymer is partially or fully homopolymerized or copolymerized in an autoclave or tubular reactor at pressures above 14,500 psi (100 MPa) using a free radical initiator, such as a peroxide (see, for example, U.S. Patent No. 4,599,392, which is incorporated herein by reference in its entirety)). LDPE resin typically has a viscosity of 0.916 g / cm³. 3 Up to 0.930 g / cm 3 The density within the range.

[0025] The term "LLDPE" includes: resins produced using Ziegler-Natta catalyst systems and resins produced using single-site catalysts, including but not limited to bismetallocene catalysts (sometimes referred to as "m-LLDPE"), phosphine imides, and geometry-restricted catalysts; and resins produced using post-metallocene molecular catalysts, including but not limited to bis(biphenylphenoxy) catalysts (also known as polyaryloxy ether catalysts). LLDPE includes linear, substantially linear, or heterogeneous ethylene-based copolymers. LLDPE contains fewer long-chain branchings than LDPE and comprises: substantially linear ethylene polymers, which are further defined in U.S. Patent Nos. 5,272,236, 5,278,272, 5,582,923, and 5,733,155, each of which is incorporated herein by reference in its entirety; homogeneous branched linear ethylene polymer compositions, such as those described in U.S. Patent No. 3,645,992, which is incorporated herein by reference in its entirety; heterogeneous branched ethylene polymers, such as those prepared according to the process disclosed in U.S. Patent No. 4,076,698, which is incorporated herein by reference in its entirety; and blends thereof (such as those disclosed in U.S. Patent Nos. 3,914,342 and 5,854,045, which are incorporated herein by reference in their entirety). LLDPE resins can be prepared by gas-phase, solution-phase, or slurry polymerization or any combination thereof, using any type of reactor or reactor configuration known in the art.

[0026] As used herein, the term "terminal carbon-carbon double bond" refers to a double bond between two carbon atoms in a polymer chain, wherein one of the carbon atoms in the double bond is a =CH2 group. Terminal double bonds are located at the ends of the polymer chain and / or at branched ends of the polymer chain. As used herein, the term "internal carbon-carbon double bond" refers to a 1,2-disubstituted carbon-carbon double bond. Internal carbon-carbon double bonds are located along the entire length of the polymer chain, but not at the ends of the polymer chain or along branched ends of the polymer chain. Terminal and internal carbon-carbon double bonds are measured by infrared spectroscopy ("IR").

[0027] As used herein, the term "olefin content" refers to the number of terminal carbon-carbon double bonds plus the number of internal carbon-carbon double bonds present per 1000 carbon atoms in the polymer chain. Olefin content is measured by infrared spectroscopy ("IR").

[0028] As used herein, the term "reaction zone" refers to the zone in which the polymerization reaction occurs. The beginning of the reaction zone is defined by the side injection of the initiator. The end of the reaction zone is defined by the reactor outlet or the next side injection of the initiator. For example, the first reaction zone is the space between the first and second injections of the initiator. The second reaction zone is the space between the second and third injections of the initiator. The third reaction zone is the space between the third and fourth injections of the initiator.

[0029] Now for reference Figure 1A method for producing ethylene can utilize a system 100 for producing ethylene. System 100 may include one or more ultra-high pressure compressors 102 operable to compress one or more medium-pressure ethylene feed streams 126 into an ethylene pre-feed stream 128 and one or more ethylene side streams 124. The ethylene pre-feed stream 128 and the one or more ethylene side streams 124 may be compressed in a single ultra-high pressure compressor 102 or in separate ultra-high pressure compressors 102. The ethylene pre-feed stream 128 may be fed to the front inlet of a high-pressure reactor 104. The one or more ethylene side streams 124 may each be fed to a respective side inlet of the high-pressure reactor 104. System 100 may include one or more initiator feed streams 116, 118, 120, such as a first initiator feed stream 116, a second initiator feed stream 118, and a third initiator feed stream 120. A first ethylene side stream 110 may be introduced into the high-pressure reactor 104 at a first side inlet. If a second initiator feed stream 118 is present, the first side inlet can be downstream of the first initiator feed stream 116 and upstream of the second initiator feed stream 118. If a second ethylene feed stream 112 is present, the second ethylene feed stream 112 can be introduced into the high-pressure reactor 104 at the second side inlet. The second side inlet can be downstream of both the first side inlet and the first initiator feed stream 116. An initiator (e.g., the second initiator feed stream 118) can be introduced into the high-pressure reactor 104 through the second side inlet (shared with the second ethylene feed stream 112), or it can be introduced downstream of the second side inlet.

[0030] If a third ethylene feed stream 114 is present, it can be introduced into the high-pressure reactor 104 at a third side inlet. This third side inlet can be downstream of the second side inlet and the second initiator feed stream 118. An initiator (e.g., a third initiator feed stream 120) can be introduced into the high-pressure reactor 104 through the third side inlet (in conjunction with the third ethylene feed stream 114), or it can be introduced downstream of the third side inlet. It should be understood that after the first initiator feed stream, the initiator feed stream can enter the reactor through a dedicated injection port, or it can be combined with the ethylene side stream before being introduced into the high-pressure reactor 104.

[0031] System 100 may further include a hydrocarbon pump 106 that pressurizes a low-pressure hydrocarbon feed stream 130 to form a hydrocarbon feed stream 108. The hydrocarbon feed stream 108 may provide a fluid connection between the hydrocarbon pump 106 and the high-pressure reactor 104. The hydrocarbon feed stream 108 may be directly connected to the high-pressure reactor 104 upstream of the first initiator feed stream 116; or the hydrocarbon feed stream 108 may be connected to an ethylene prefeed stream 128 upstream of the first initiator feed stream 116. The hydrocarbon feed stream 108 may be connected to an ethylene prefeed stream 128 downstream of the ultra-high pressure compressor 102. Without being theoretically limited, it is believed that introducing a mixture of hydrocarbon molecules into the ethylene feed stream upstream of the ultra-high pressure compressor 102 may lead to undesirable ethylene polymerization, thereby causing fouling of the ultra-high pressure compressor 102.

[0032] A method for producing low-density polyethylene (LDPE) may include feeding ethylene into a front inlet of a high-pressure reactor; feeding ethylene into one or more side inlets of a high-pressure reactor; and feeding a mixture of hydrocarbon molecules into a high-pressure reactor. The method may further include feeding an initiator into the high-pressure reactor 104 between the front inlet and a first side inlet.

[0033] The method may include feeding ethylene into the front inlet of the high-pressure reactor 104 at a pressure of at least 1000 bar, such as at least 1200 bar, at least 1500 bar, at least 1700 bar, at least 2000 bar, 1000 bar to 4000 bar, 1200 bar to 4000 bar, 1500 bar to 4000 bar, 1700 bar to 4000 bar, 2000 bar to 4000 bar, 2000 bar to 3200 bar, or any subset thereof.

[0034] At least 20% by weight of the total ethylene fed to high-pressure reactor 104 may be fed to the front inlet of high-pressure reactor 104. The ethylene fed to the front inlet of high-pressure reactor 104 may be fed upstream of the injection point of the first initiator feed stream 116. In an embodiment, at least 25%, at least 30%, at least 40%, at least 45%, at least 50%, about 50%, 25% to 60%, 30% to 60%, 40% to 60%, or any subset thereof of the total ethylene fed to high-pressure reactor 104 may be fed to the front inlet of high-pressure reactor 104.

[0035] The method may include feeding ethylene into one or more side inlets of a high-pressure reactor at a pressure of at least 1000 bar, such as at least 1200 bar, at least 1500 bar, at least 1700 bar, at least 2000 bar, 1000 bar to 4000 bar, 1200 bar to 4000 bar, 1500 bar to 4000 bar, 1700 bar to 4000 bar, 2000 bar to 4000 bar, 2000 bar to 3200 bar, or any subset thereof.

[0036] At least 20% by weight of the total ethylene fed to high-pressure reactor 104 may be fed to the first side inlet of high-pressure reactor 104. The ethylene fed to the first side inlet of high-pressure reactor 104 may be fed downstream of the injection point of the first initiator feed stream 116, and, if a second initiator feed stream 118 is present, may be fed upstream of the injection point of the second initiator feed stream 118. In an embodiment, at least 25%, at least 30%, at least 40%, at least 45%, at least 50%, about 50%, 25% to 60%, 30% to 60%, 40% to 60%, or any subset thereof of the total ethylene fed to high-pressure reactor 104 may be fed to the first side inlet of high-pressure reactor 104.

[0037] In the implementation scheme, all or substantially all of the ethylene introduced into the high-pressure reactor 104 may be introduced through the front inlet and the first side inlet. For example, at least 80% by weight, at least 90% by weight, at least 95% by weight, or at least 99% by weight of the ethylene introduced into the high-pressure reactor 104 may be introduced through the front inlet and the first side inlet.

[0038] In an embodiment in which all or substantially all of the ethylene is introduced into the high-pressure reactor 104 via a front inlet and a first side inlet, 40% to 60% of the ethylene introduced into the high-pressure reactor 104 may be introduced via the front inlet, and 40% to 60% of the ethylene introduced into the high-pressure reactor 104 may be introduced via the first side inlet.

[0039] The method may further include feeding ethylene into a second side inlet of the high-pressure reactor 104. Such embodiments may further include feeding an initiator into the high-pressure reactor 104 between the first and second side inlets, or feeding the initiator into the high-pressure reactor 104 through the second side inlet.

[0040] In the implementation scheme, all or substantially all of the ethylene introduced into the high-pressure reactor 104 may be introduced through the front inlet, the first side inlet, and the second side inlet. For example, at least 80% by weight, at least 90% by weight, at least 95% by weight, or at least 99% by weight of the ethylene introduced into the high-pressure reactor 104 may be introduced through the front inlet, the first side inlet, and the second side inlet.

[0041] In an embodiment where ethylene is introduced into the high-pressure reactor 104 via a front inlet, a first side inlet, and a second side inlet, 20% to 45% of the ethylene introduced into the high-pressure reactor 104 may be introduced through the front inlet, 20% to 45% of the ethylene introduced into the high-pressure reactor 104 may be introduced through the first side inlet, and 20% to 45% of the ethylene introduced into the high-pressure reactor 104 may be introduced through the second side inlet. 20% to 40%, 20% to 35%, 25% to 45%, 30% to 45%, 25% to 40%, 30% to 35%, or any subset thereof of the ethylene introduced into the high-pressure reactor 104 may be introduced through the front inlet. 20% to 40%, 20% to 35%, 25% to 45%, 30% to 45%, 25% to 40%, 30% to 35%, or any subset thereof of the ethylene introduced into the high-pressure reactor 104 may be introduced through the first side inlet. Ethylene introduced into the high-pressure reactor 104 at 20% to 40% by weight, 20% to 35% by weight, 25% to 45% by weight, 30% to 45% by weight, 25% to 40% by weight, 30% to 35% by weight, or any subset thereof, may be introduced through the second side inlet.

[0042] The method may further include feeding ethylene into a third side inlet of the high-pressure reactor 104. Such embodiments may further include feeding an initiator into the high-pressure reactor 104 between the second side inlet and the third side inlet, or feeding the initiator into the high-pressure reactor 104 through the third side inlet.

[0043] In the implementation scheme, all or substantially all of the ethylene introduced into the high-pressure reactor 104 may be introduced through the front inlet, the first side inlet, the second side inlet, and the third side inlet. For example, at least 80% by weight, at least 90% by weight, at least 95% by weight, or at least 99% by weight of the ethylene introduced into the high-pressure reactor 104 may be introduced through the front inlet, the first side inlet, the second side inlet, and the third side inlet.

[0044] In one embodiment where ethylene is introduced into the high-pressure reactor 104 via a front inlet, a first side inlet, a second side inlet, and a third side inlet, 20% to 45% by weight of the ethylene introduced into the high-pressure reactor 104 may be introduced through the front inlet, 20% to 45% by weight of the ethylene introduced into the high-pressure reactor 104 may be introduced through the first side inlet, 20% to 45% by weight of the ethylene introduced into the high-pressure reactor 104 may be introduced through the second side inlet, and 20% to 45% by weight of the ethylene introduced into the high-pressure reactor 104 may be introduced through the third side inlet.

[0045] Ethylene in high-pressure reactor 104 may be introduced at 20% to 40% by weight, 20% to 35% by weight, 20% to 30% by weight, 25% to 45% by weight, 30% to 45% by weight, 25% to 40% by weight, 30% to 35% by weight, or any subset thereof, through the front inlet. Ethylene in high-pressure reactor 104 may be introduced at 20% to 40% by weight, 20% to 35% by weight, 20% to 30% by weight, 25% to 45% by weight, 30% to 45% by weight, 25% to 40% by weight, 30% to 35% by weight, or any subset thereof, through the first side inlet. Ethylene in high-pressure reactor 104 may be introduced at 20% to 40% by weight, 20% to 35% by weight, 20% to 30% by weight, 25% to 45% by weight, 30% to 45% by weight, 25% to 40% by weight, 30% to 35% by weight, or any subset thereof, via a second side inlet. Ethylene in high-pressure reactor 104 may be introduced at 20% to 40% by weight, 20% to 35% by weight, 20% to 30% by weight, 25% to 45% by weight, 30% to 45% by weight, 25% to 40% by weight, 30% to 35% by weight, or any subset thereof, via a third side inlet.

[0046] The total amount of ethylene fed into the high-pressure reactor 104 may include a mixture of recycled ethylene and fresh (“supplementary”) ethylene. At least 40% by weight, at least 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, at least 90% by weight, at least 95% by weight, or at least 99% by weight of fresh ethylene supplied to the high-pressure reactor 104 may be introduced into the front side of the high-pressure reactor 104.

[0047] Without being limited by theory, the ethylene feed locations shown in this paper are considered to be the most effective, with less ethylene side flow (such as 3, 2 or 1), and optionally 3, 2 or 1 initiator injection points.

[0048] Initiators introduced into high-pressure reactor 104 via one or more initiator feed streams 116, 118, 120 may comprise compounds capable of forming free radicals. The initiator may enter high-pressure reactor 104 through a dedicated injection port or may be combined with an ethylene-side feed stream prior to entering high-pressure reactor 104. Suitable initiators may include peroxides. Non-limiting examples of initiators include organic peroxides such as cyclic peroxides, diacyl peroxides, dialkyl peroxides, hydroperoxides, peroxycarbonates, peroxydicarbonates, peroxyesters, peroxyketals, tert-butylperoxyneopentate, di-tert-butyl peroxide, tert-butylperoxyacetate, and tert-butylperoxy-2-hexanoate, and combinations thereof. In one embodiment, these organic peroxy initiators may be used in amounts from 0.001% by weight to 0.2% by weight, based on the total weight of the polymerizable monomers.

[0049] In an embodiment, a chain transfer agent (CTA) system may be introduced at one or more points along the reactor. The term "CTA system" includes a single CTA or a mixture of CTAs added to the polymerization process, typically used to control the melt index. A CTA system comprises a component capable of transferring hydrogen atoms to a growing polymer molecule containing free radicals, which are formed on the CTA molecule by the component, and the CTA molecule can then initiate a new polymer chain. CTA is also known as a telomer or telomerizer. By way of example, but not limited to, a CTA system may include: propylene, isobutane, n-butane, 1-butene, methyl ethyl ketone, acetone, ethyl acetate, propionaldehyde, ISOPAR (ExxonMobil Chemical Co.), and isopropanol. In one embodiment, the amount of CTA used in the method may be from 0.01% by weight to 10% by weight of the total reaction mixture.

[0050] As used herein, the term "CTA activity" or "chain transfer activity coefficient (Cs value)" refers to the ratio between the "chain transfer rate" and the "ethylene growth rate." See the Mortimer references provided in the Experiments section below.

[0051] As used herein, the term "Z1 / Zi" is determined as follows: "CTA in reactor zone i". j The molar concentration in the reactor zone ([CTA]) ji ")" is defined as "the total molar amount of CTA fed into reactor zones k = 1 to k = i (excluding the amount transferred from previous reaction zones)" divided by "the total molar amount of ethylene fed into reactor zones 1 to i (excluding the amount transferred from previous reaction zones)". Note that i ≥ 1. This relationship is shown in equation AC below.

[0052] (Equation AC)

[0053] In equation AC, j ≥ 1, It is "the molar amount of the j-th CTA freshly injected into the k-th reactor zone (where k = 1 to i)", and It is "the molar amount of ethylene freshly injected into the kth reactor zone (where k = 1 to i)".

[0054] The chain transfer activity (Zi) of CTA (system) in reactor zone I is defined as the sum of the reactor zone molar concentrations of each CTA in the reactor zone multiplied by its chain transfer activity constant (Cs) – see Equation BC. The chain transfer activity constant (Cs) is the ratio of the reaction rate Ks / Kp at a reference pressure (1360 atm) and a reference temperature (130 °C). This relationship is shown in Equation BC below, where n compi This represents the total number of CTAs in reactor zone i. Note that i ≥ 1, and n compi ≥ 1.

[0055] (Equation BC).

[0056] As used herein, the term “Rn = RZ1 / RZn” refers to the ratio of “molar parts of fresh ethylene fed into the first reaction zone (RZ1)” to “molar parts of fresh ethylene fed into reaction zone n (RZn)” for reaction zone n.

[0057] In one implementation, all fresh (“supplementary”) CTA can be fed into the second reaction zone. In the second implementation, the CTA / ethylene feed ratio is the same in each reaction zone following the first reaction zone.

[0058] In the implementation scheme, all fresh ethylene and up to 30 mol% of fresh CTA, such as up to 25 mol%, up to 20 mol%, up to 15 mol%, up to 10 mol%, up to 5 mol%, or up to 1 mol%, may be fed into the first reaction zone.

[0059] In the implementation scheme, the concentration of CTA in reaction zone 2 relative to the CTA in reaction 1 (Z2 / Z1) can be greater than 0.5, such as greater than 0.6, greater than 0.8, greater than 1.0, greater than 1.2, greater than 1.5, greater than 1.7, 0.5 to 1.8, 0.6 to 1.8, 0.8 to 1.8, 1.0 to 1.8, 1.2 to 1.8, 1.4 to 1.8, 1.6 to 1.8, 0.5 to 1.5, 0.5 to 1.2, 0.5 to 0.9, 0.7 to 1.3, or any subset thereof.

[0060] In the implementation scheme, the concentration of CTA in reaction zone 3 relative to the CTA in reaction 1 (Z3 / Z1) can be greater than 0.2, such as greater than 0.3, greater than 0.4, greater than 0.5, greater than 0.6, greater than 0.7, greater than 0.8, greater than 0.9, 0.2 to 1.0, 0.4 to 1.0, 0.6 to 1.0, 0.8 to 1.0, 0.2 to 0.8, 0.2 to 0.6, 0.2 to 0.4, 0.4 to 0.8, or any subset thereof.

[0061] In the implementation scheme, the concentration of CTA in reaction zone 4 relative to the CTA in reaction 1 (Z4 / Z1) can be greater than 0.2, such as greater than 0.3, greater than 0.4, greater than 0.5, greater than 0.6, greater than 0.7, 0.2 to 0.8, 0.4 to 0.8, 0.6 to 0.8, 0.2 to 0.6, 0.2 to 0.4, or any subset thereof.

[0062] The method may include feeding a mixture of hydrocarbon-based molecules into a high-pressure reactor 104. Each hydrocarbon-based molecule in the mixture may consist of hydrogen and carbon atoms.

[0063] Each hydrocarbon-based molecule in the mixture of hydrocarbon-based molecules may contain three or more carbon-carbon double bonds. In embodiments, each hydrocarbon-based molecule may contain 3 to 40 carbon-carbon double bonds, such as at least 5, at least 7, at least 9, at least 12, 3 to 30, 3 to 20, 3 to 18, 3 to 14, 3 to 12, 3 to 5, 5 to 40, 7 to 40, 9 to 40, 12 to 40, 12 to 20, or any subset thereof.

[0064] Each hydrocarbon-based molecule's polymer chain may be branched and contain three or more ends. In an embodiment, carbon-carbon double bonds may be present at each end. Three or more carbon-carbon double bonds may be terminal groups. For example, at least 3, 5, 7, 9, 12 or more carbon-carbon double bonds may be terminal groups.

[0065] A mixture of hydrocarbon-based molecules may contain two or more hydrocarbon-based molecules that are different in structure, properties and / or composition.

[0066] Mixtures based on hydrocarbon molecules can have a number-average molecular weight (Mn) of 350 g / mol to 4000 g / mol, such as 400 g / mol to 4000 g / mol, 500 g / mol to 4000 g / mol, 800 g / mol to 4000 g / mol, 1000 g / mol to 4000 g / mol, 400 g / mol to 3000 g / mol, 400 g / mol to 2500 g / mol, 400 g / mol to 1500 g / mol, 800 g / mol to 1200 g / mol, or any subset thereof.

[0067] Some or all hydrocarbon-based molecules can have structure I:

[0068]

[0069] In structure I, R = H or OH, n (the number of terminal carbon-carbon double bonds) can be 3 to 160, such as 5 to 160, 10 to 160, 20 to 160, 30 to 160 or 40 to 160, 5 to 100 or 9 to 40; m (the number of internal carbon-carbon double bonds) can be 0 to 50, such as 0 to 30, 1 to 50, 1 to 40, 1 to 30, 1 to 20, 2 to 20, 2 to 10 or any subset thereof.

[0070] All or part of hydrocarbon-based molecules can have structure II

[0071]

[0072] In structure II, R = H or OH, n (the number of terminal carbon-carbon double bonds) can be 3 to 160, and m (the number of internal carbon-carbon double bonds) can be 0 to 50; x can be 0 to 160, and y can be 0 to 50. For example, n can be 3 to 160, such as 5 to 160, 10 to 160, 20 to 160, 30 to 160 or 40 to 160, 5 to 100 or 9 to 40; m can be 0 to 50, such as 0 to 30, 1 to 50, 1 to 40, 1 to 30, 1 to 20, 2 to 20, 2 to 10 or any subset thereof. X can be 0 to 160, such as 0 to 140, 0 to 120, 0 to 100, 0 to 80, 0 to 60, 0 to 40, 0 to 20, 1 to 20, 1 to 60, 1 to 100, 1 to 160, 10 to 150, 20 to 140, 40 to 120, 60 to 100, or any subset thereof. Y can be 0 to 40, 0 to 30, 0 to 20, 0 to 10, 1 to 50, 5 to 50, 10 to 60, 20 to 50, 30 to 50, 40 to 50, 10 to 40, or any subset thereof.

[0073] The average n content in a mixture of hydrocarbon-based molecules can be from 9 to 40, and the average m content can be from 1 to 10. The “average n content” is calculated by dividing the number-average molecular weight (Mn) of the hydrocarbon-based molecules by the weight-average molecular weight (Mw) of the hydrocarbon-based molecules, and then multiplying by the fraction of terminal carbon-carbon double bonds. The “average m content” is calculated by dividing the number-average molecular weight (Mn) of the hydrocarbon-based molecules by the weight-average molecular weight (Mw) of the hydrocarbon-based molecules, and then multiplying by the fraction of internal carbon-carbon double bonds. Mixtures of hydrocarbon-based molecules can have the following corresponding average n content and average m content (denoted as “n / m”, see Structure I for each hydrocarbon-based molecule): 9-40 / 1-10, or 12-38 / 2-8, or 13-37 / 2-6, or 15-35 / 2-6, or 19 / 3 or 33 / 5. The hydrocarbon-based molecules of structure I, the hydrocarbon-based molecules of structure II, and / or the total mixture of hydrocarbon-based molecules may have an m+n content of 5 to 30, such as 5 to 25, 5 to 20, 10 to 30, 15 to 30, 10 to 30, 15 to 25, 15 to 20, or any subset thereof.

[0074] The hydrocarbon-based molecules of structure I, the hydrocarbon-based molecules of structure II, and / or the total mixture of hydrocarbon-based molecules may have a molecular weight distribution of 1.2 to 20, such as 1.2 to 10, 1.2 to 5, 1.2 to 3, 1.3 to 20, 1.4 to 20, 1.5 to 20, 2 to 20, 5 to 20, 10 to 20, 2 to 18, 6 to 16, 8 to 14, or any subset thereof.

[0075] In Structures I and II, it should be understood that hydrocarbon-based molecules can be random copolymers or block copolymers. The monomers may, but need not, be arranged in the same order as shown in Structures I and II. Any polymer comprising the two monomers shown in Structure I (and only those two monomers) is defined by Structure I. Any polymer comprising all four monomers shown in Structure II (and only those monomers) is defined by Structure II, regardless of the monomer order.

[0076] Mixtures of hydrocarbon-based molecules may comprise hydrocarbon-based molecules of structure I, hydrocarbon-based molecules of structure II, or combinations thereof. Suitable hydrocarbon-based molecules include those described in detail in U.S. Patent Application No. 17 / 294,538, the entirety of which is incorporated herein by reference; and include 1,2-polybutadiene, which may be named PB B-1000 (1,2-polybutadiene having a number average molecular weight (Mn) of 1200 and a 1,2-vinyl content of at least 85%) and PB B-2000 (1,2-polybutadiene having a number average molecular weight (Mn) of 2000 and a 1,2-vinyl content of at least 90%), available from Nippon Soda Co., Ltd.

[0077] The hydrocarbon-based mixture can be introduced into the high-pressure reactor 104 in an amount such that the weight ratio of the hydrocarbon-based mixture to ethylene is less than 0.01 (1 wt% of the total weight of ethylene introduced into the high-pressure reactor). In an embodiment, the weight ratio of the hydrocarbon-based mixture to ethylene, based on the total weight of ethylene fed into the high-pressure reactor 104, can be from 0.01 wt% to 1 wt%, 0.05 wt% to 1 wt%, 0.01 wt% to 0.5 wt%, 0.01 wt% to 0.3 wt%, 0.01 wt% to 0.2 wt%, 0.05 wt% to 0.15 wt%, or any subset thereof.

[0078] At least 40 wt% of a mixture of hydrocarbon-based molecules may be fed into the front inlet of high-pressure reactor 104. Without being theoretically limited, it has been found that introducing at least 40 wt% (such as all or substantially all) of a mixture of hydrocarbon-based molecules into the front inlet of high-pressure reactor 104 can result in improved melt strength and molecular weight distribution at a lower concentration of the hydrocarbon-based mixture, compared to introducing the mixture at one or more side inlets of the high-pressure reactor. In embodiments, at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, at least 99 wt%, or even at least 99.9 wt% of a mixture of hydrocarbon-based molecules may be fed into the front inlet of high-pressure reactor 104. It should be understood that the front inlet of high-pressure reactor 104 is upstream of the first initiator injection point. In embodiments, the remainder of the hydrocarbon-based mixture may be fed into the high-pressure reactor in a second reaction zone.

[0079] In one embodiment, the remainder of the hydrocarbon-based molecular mixture not fed to the front side of the high-pressure reactor 104 may be fed to that side inlet of the high-pressure reactor in proportion to the amount of ethylene fed to one or more side inlets of the high-pressure reactor. For example, if 50% of the total hydrocarbon-based molecular mixture is fed to the front side of the reactor, 60% of the ethylene fed to the side of the reactor is fed to the second reaction zone, and 40% of the ethylene fed to the side of the reactor is fed to the third reaction zone, then 50% of the total hydrocarbon-based molecular mixture is fed to the front side of the reactor, 30% of the total hydrocarbon-based molecular mixture is fed to the second reaction zone, and 20% of the total hydrocarbon-based molecular mixture is fed to the third reaction zone.

[0080] A majority (e.g., all or substantially all) of the hydrocarbon-based molecule mixture may be fed into a high-pressure reactor 104 downstream of at least one ultra-high-pressure compressor 102. Without being theoretically limited, it has been found that introducing the hydrocarbon-based molecule mixture into the ultra-high-pressure compressor 102 may result in increased fouling of the ultra-high-pressure compressor. Typically, the presence of ethylene during pressurization of the hydrocarbon-based molecule mixture has been found to exacerbate this increased fouling. In embodiments, at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt%, at least 95 wt%, at least 99 wt%, or even at least 99.9 wt% of the hydrocarbon-based molecule mixture may be fed into the high-pressure reactor 104 at a point downstream of at least one ultra-high-pressure compressor 102. Based on the total molar amount of gas in the pressurizing device (such as a pump), a mixture of hydrocarbon-based molecules can be pressurized to the operating pressure of the high-pressure reactor 104 (such as at least 1000 bar, at least 1200 bar, at least 1500 bar, at least 1700 bar, at least 2000 bar, 1000 bar to 4000 bar, 1700 bar to 4000 bar, 2000 bar to 4000 bar, 2000 bar to 3200 bar, or any subset thereof) in the presence of less than 0.1 mol% (such as less than 0.01 mol%, less than 0.001 mol%, or even less than 0.00001 mol%) of ethylene.

[0081] It is possible to pressurize a mixture of hydrocarbon-based molecules while simultaneously diluting it with a hydrocarbon solvent, heating it (such as to a temperature of at least 40°C or at least 50°C), or both.

[0082] This method may include polymerizing ethylene and a mixture of hydrocarbon-based molecules in a high-pressure reactor 104 to produce low-density polyethylene (LDPE). The high-pressure reactor 104 may be a tubular reactor or an autoclave reactor. When using an autoclave reactor, it may be a stirred autoclave reactor with one or more reaction zones. The autoclave reactor may have several injection points for initiator or monomer feed, or both. When a tubular reactor is used as the high-pressure reactor 104, it may include a jacketed tube with one or more reaction zones. Suitable reactor lengths may be from 100 m to 3000 m or from 1000 m to 2000 m. The start of the reaction zone in either type of reactor is typically defined by the lateral injection of the initiator, ethylene, chain transfer agent (or telomer), comonomer, and any combination thereof. The high-pressure method may be carried out in an autoclave reactor or a tubular reactor with one or more reaction zones, or in a combination of an autoclave reactor and a tubular reactor, each containing one or more reaction zones.

[0083] This method may include producing LDPE via free radical polymerization at pressures of at least 1000 bar, such as at least 1200 bar, at least 1500 bar, at least 1700 bar, at least 2000 bar, 1000 to 4000 bar, 1200 to 4000 bar, 1500 to 4000 bar, 1700 to 4000 bar, 2000 to 4000 bar, 2000 to 3200 bar, or any subset thereof. Without being theoretically limited, it has been found that LDPE can be produced at lower pressures when using an autoclave reactor than when using a tubular reactor. In one embodiment, the high-pressure reactor 104 may be an autoclave reactor, and free radical polymerization may occur at pressures of 1500 to 4000 bar. In another embodiment, the high-pressure reactor 104 may be a tubular reactor, and free radical polymerization may occur at pressures of 2000 to 4000 bar.

[0084] LDPE can be formed via free radical polymerization at peak reaction temperatures ranging from 270°C to 320°C, such as 275°C to 320°C, 280°C to 320°C, 285°C to 320°C, 290°C to 320°C, 295°C to 320°C, 300°C to 320°C, 275°C to 315°C, 275°C to 310°C, 275°C to 305°C, 275°C to 300°C, or any subset thereof.

[0085] LDPE can be formed via free radical polymerization at initial to peak temperature differences of 130°C to 170°C, such as 130°C to 165°C, 130°C to 160°C, 130°C to 155°C, 130°C to 150°C, 130°C to 145°C, 135°C to 170°C, 140°C to 170°C, 145°C to 170°C, or any subset thereof.

[0086] This method may result in at least 50% by weight of the hydrocarbon-based molecule mixture introduced into the reactor, such as at least 55% by weight, at least 60% by weight, at least 65% by weight, at least 68% by weight, or at least 70% by weight.

[0087] LDPE can have a melt strength of at least 20 mN, such as at least 25 mN, at least 30 mN, at least 35 mN, at least 40 mN, at least 50 mN, or at least 60 mN.

[0088] LDPE may have a Mw / Mn ratio of at least 9.0, such as at least 10.0, at least 11.0, at least 12.0, at least 14.0, at least 16.0, at least 18.0, at least 20.0, 9.0 to 25, 10 to 25, 11 to 25, 12 to 25, 14 to 25, or any subset thereof (also referred to herein as “molecular weight distribution” and “polydispersity index”). Mw / Mn can be determined by conventional gel permeation chromatography-size exclusion chromatography.

[0089] LDPE can have a concentration range of 0.1 g / 10 min to 100 g / 10 min, such as 0.5 g / 10 min to 100 g / 10 min, 1 g / 10 min to 100 g / 10 min, 2 g / 10 min to 100 g / 10 min, 3 g / 10 min to 100 g / 10 min, 4 g / 10 min to 100 g / 10 min, 0.1 g / 10 min to 75 g / 10 min, 0.1 g / 10 min to 50 g / 10 min, 0. Melt flow rates (I2) (also referred to herein as “melt index (I2)”) of 1 g / 10 min to 25 g / 10 min, 0.1 g / 10 min to 12 g / 10 min, 0.1 g / 10 min to 8 g / 10 min, 0.1 g / 10 min to 6 g / 10 min, 1 g / 10 min to 10 g / 10 min, 2 g / 10 min to 8 g / 10 min, 3 g / 10 min to 5 g / 10 min or any subset thereof.

[0090] LDPE can have a concentration of 0.916 g / cm³. 3 Up to 0.924 g / cm 3 Such as 0.916 g / cm3 to 0.922 g / cm3 3 0.916 g / cm³ to 0.920 g / cm³ 3 0.916 g / cm³ to 0.918 g / cm³ 3 0.917 g / cm³ to 0.924 g / cm³ 3 Or 0.919 g / cm³ to 0.924 g / cm³ 3 The density.

[0091] LDPE can have a hexane extractable content of less than 2.6% by weight, such as less than 2.5% by weight, less than 2.25% by weight, less than 2.0% by weight, less than 1.5% by weight, less than 1% by weight, or even less than 0.5% by weight, based on the total weight of the polymer.

[0092] LDPE can have necking from 1.0 inch to 3.0 inch, such as 1.25 inch to 3.0 inch, 1.5 inch to 3.0 inch, 1.75 inch to 3.0 inch, 2.0 inch to 3.0 inch, 1.0 inch to 2.75 inch, 1.0 inch to 2.5 inch, 1.0 inch to 2.25 inch, 1.0 inch to 2.0 inch, or any subset thereof. Necking is calculated at a draw rate of 440 feet per minute (fpm).

[0093] LDPE can have stretches of 800 fpm to 1500 fpm, such as 900 fpm to 1500 fpm, 1000 fpm to 1500 fpm, 1200 fpm to 1500 fpm, 800 fpm to 1400 fpm, 800 fpm to 1300 fpm, 800 fpm to 1100 fpm, or any subset thereof.

[0094] It should be understood that these melt strengths, molecular weight distributions, and melt flow rates can be achieved at a ratio of less than 0.01 (1% by weight of hydrocarbon-based molecular mixture based on the total weight of ethylene introduced into the high-pressure reactor), such as less than or equal to 0.001 (0.1% by weight).

[0095] Test methods

[0096] Melt flow rate (melt index)

[0097] The melt index I2 of the polymer samples was measured at 190°C and 2.16 kg load according to ASTM D-1238 (Method B).

[0098] density

[0099] Samples for density measurement are prepared according to ASTM D4703. According to ASTM D792, Method B involves measuring the sample within one hour of pressing it.

[0100] Gel permeation chromatography (GPC) and size exclusion chromatography (SEC) (conventional and absolute GPC)

[0101] GPC-SEC (regular and absolute GPC) measurements were performed according to the test procedures defined in PCT Publication WO2021108134.

[0102] melt strength

[0103] Melt strength was determined according to the test procedure defined in PCT Publication WO2020112873.

[0104] Melt force

[0105] Melt force was measured according to the test procedure defined in PCT Publication WO2021108134.

[0106] Hexane extractables

[0107] The concentration of hexane extractables was determined according to the test procedure described in U.S. Patent No. US9334348B2.

[0108] neck constriction and stretching

[0109] Necking and draw are measured as follows: Draw is defined as the maximum linear velocity achievable before web breakage or web defects / edge inconsistencies occur when accelerating at a constant polymer output. Necking is the difference between the final width of the web and the die width at a fixed linear velocity. Necking was measured at a draw rate of 440 fpm. Lower necking and higher draw are both highly desirable. Lower necking indicates better web dimensional stability, which in turn provides better control over coatings on the substrate. Higher draw indicates higher linear velocity capability, which in turn provides better productivity.

[0110] Aggregation Simulation

[0111] Aggregation simulation was performed according to the procedure described in U.S. Patent No. US10005863B2.

[0112] Simulated Melt Forces: Empirical models have been developed to predict the melt forces of simulated polymers using JMP software. JMP modeling is essentially a direct statistical optimization technique where equations are selected based on insights into the body dependence of melt strength / melt force on inputs such as Mw, Mn, SCB, LCB, and broadening factors (when branching agents are added). Then, given the input values ​​of the relevant quantities, the numerical coefficients in the equations are explicitly established through least-squares optimization of the output values.

[0113] Example

[0114] Material

[0115] In all embodiments, polybutadiene was used as a mixture of hydrocarbon-based molecules. Specifically, the polybutadiene used was PB B-1000 supplied by Nippon Soda, Co., Ltd. PB B-1000 has 1200 g / mol Mn, 1.47 Mw / Mn, 85% terminal carbon-carbon double bonds, 15% internal carbon-carbon double bonds, an average n content of 19, and an average m content of 3. “m” and “n” are calculated by dividing Mn by the Mw of the butadiene monomer (hydrocarbon-based molecule) and multiplying by the fraction of terminal carbon-carbon double bonds (for n) and the fraction of internal carbon-carbon double bonds (for m). For example: Mn = 1200 g / mol, average n = (1200 g / mol) / (54.09 g / mol butadiene monomer) = 22 repeating units * 0.85 (terminal / total olefins) = average 18.8 terminal vinyl groups per chain.

[0116] Example 1

[0117] In a first embodiment, a series of sample LDPEs are formed according to the method described herein. As described above, PB B-100 is used as a mixture of hydrocarbon-based molecules. Figure 2 The indicated amounts of a hydrocarbon-based molecule mixture are combined with ethylene. At a reactor inlet pressure of approximately 2100 bar and peak temperatures of approximately 295°C in all reaction zones, 50% by weight of ethylene is fed into the front inlet of the tubular reactor, and 50% by weight of ethylene is fed into the first side inlet of the tubular reactor. An initiator is fed into a first initiator injection point upstream of the first side inlet. In one embodiment, the hydrocarbon-based molecule mixture is fed into the front inlet of the reactor, and in another embodiment, the hydrocarbon-based molecule mixture is fed into the side of the reactor.

[0118] from Figure 2 It can be seen that regardless of whether the hydrocarbon-based molecule mixture is supplied to the front or side of the reactor, increasing the concentration of the hydrocarbon-based molecule mixture increases the melt strength of the produced LDPE. Figure 2 It can be seen that the effect is significantly more pronounced when a mixture of at least 40% by weight (such as all) of hydrocarbon-based molecules is fed to the front of the reactor, thereby achieving higher melt strength at lower concentrations of hydrocarbon-based molecules.

[0119] Example 2

[0120] Now for reference Figure 3Reference LDPE (CE-A) was formed in the same manner as in Example 1, except that no branching agent was added. Then, comparative LDPE (CE-B) was formed in the same manner as in Example 1, however, PB B-1000 branching agent was added to the side of the reactor, wherein the total branching agent concentration was 0.4% based on the total weight of ethylene. Finally, LDPE (EX-1) was formed in the same manner as in Example 1, however, PB B-1000 branching agent was added to the front side of the reactor, wherein the total branching agent concentration was 0.36% based on the total weight of ethylene.

[0121] from Figure 3 It can be seen that, compared with Reference Example CE-A and Comparative Example CE-B, introducing the branching agent into the front side of the reactor results in a significant broadening of the molecular weight distribution of LDPE.

[0122] Example 3

[0123] For all the methods shown in Example 3, the PB B-1000 was used as a mixture based on hydrocarbon molecules. The reactor was operated under the conditions shown in Table 1. The results are shown in Table 2.

[0124] As used in Table 2, the feed location “super suction” refers to the direct upstream of the ultra-high pressure compressor. The feed location “super discharge” refers to the downstream of the ultra-high pressure compressor, such as between the ultra-high pressure compressor and the high-pressure reactor, or at the inlet of the high-pressure reactor.

[0125] Table 1A

[0126]

[0127] Table 1B

[0128]

[0129] Table 2

[0130]

[0131] The results of the GPC test are shown in Table 3.

[0132] Table 3

[0133]

[0134] As can be seen from Table 3, feeding at least 40% of the hydrocarbon-based molecule mixture to the front of the reactor in the embodiments of this disclosure results in an increase in all higher molecular weight moments (Mw, Mz, and Mz+1). These higher molecular weight moments are considered to be related to increased melt forces.

[0135] For purposes of description and limitation of this disclosure, it should be noted that the terms “about” or “approximately” are used in this disclosure to indicate the degree of uncertainty attributable to any quantitative comparison, value, measurement or other representation. The terms “about” and / or “approximately” are also used in this disclosure to indicate the degree to which a quantitative representation may vary from a specified reference without causing a fundamental change in the subject matter of interest.

[0136] It should be noted that one or more of the appended claims use the term "wherein" as a transitional expression. For the purpose of defining this technology, it should be noted that this term is introduced in the claims as an open transitional phrase used to introduce a description of a series of features of the structure, and should be interpreted in a similar manner to the more commonly used open prepositional term "comprising".

[0137] Any quantitative value expressed in this application may be considered to include open-ended embodiments conforming to the transitional phrases “comprising” or “including”, as well as closed or partially closed embodiments conforming to the transitional phrases “consisting of” and “substantially consisting of”.

[0138] It should also be noted that references to “at least one / a” components, elements, etc. in this article should not be used to make inferences that alternative uses of the article “a / a” should be limited to a single component, element, etc.

Claims

1. A method for producing low-density polyethylene (LDPE), the method comprising: Ethylene is fed into the front inlet of the high-pressure reactor at a pressure of at least 1000 bar; Ethylene is fed into one or more side inlets of the high-pressure reactor at a pressure of at least 1000 bar; as well as A mixture of hydrocarbon-based molecules is fed into the high-pressure reactor downstream of at least one ultra-high-pressure compressor, wherein each hydrocarbon-based molecule contains three or more carbon-carbon double bonds; wherein: At least 20% by weight of the total ethylene fed into the high-pressure reactor is fed into the front inlet of the high-pressure reactor; At least 20% by weight of the total ethylene fed into the high-pressure reactor is fed into the first side inlet of the high-pressure reactor. At least 40% by weight of the mixture of the hydrocarbon-based molecules is fed into the front inlet of the high-pressure reactor to produce the LDPE via free radical polymerization at a pressure of at least 1000 bar.

2. The method for producing LDPE according to claim 1, the method further comprising feeding an initiator into the high-pressure reactor between the front inlet and the first side inlet.

3. The method for producing LDPE according to claim 1 or 2, wherein: The high-pressure reactor includes at least three reaction zones; The Z2 / Z1 ratio is between 0.5 and 1.8; The Z3 / Z1 ratio is between 0.2 and 1.0; and The Z4 / Z1 ratio is between 0.2 and 0.

8.

4. The method for producing LDPE according to any one of claims 1 to 3, the method further comprising: An initiator is fed into the high-pressure reactor between the first side inlet and the second side inlet; as well as Ethylene is fed into the second side inlet of the high-pressure reactor.

5. The method for producing LDPE according to any one of claims 1 to 4, wherein the ratio of the total weight of the hydrocarbon-based molecule mixture to the total weight of ethylene introduced into the high-pressure reactor is less than 0.

01.

6. The method for producing LDPE according to any one of claims 1 to 5, wherein the hydrocarbon-based molecule mixture has a number-average molecular weight (Mn) of 350 g / mol to 4000 g / mol.

7. The method for producing LDPE according to any one of claims 1 to 6, wherein the hydrocarbon-based molecule has structure I: Structure I , where R is H or OH, n is 3 to 160, and m is 0 to 50.

8. The method for producing LDPE according to any one of claims 1 to 7, wherein the hydrocarbon-based molecule has structure II: Structure II Where R is H or OH, n is 3 to 160 and m is 0 to 50; x is 0 to 160 and y is 0 to 50.

9. The method for producing LDPE according to any one of claims 1 to 8, wherein the hydrocarbon-based molecule mixture has a molecular weight distribution of 1.2 to 10.

10. The method for producing LDPE according to any one of claims 1 to 9, wherein the high-pressure reactor is a tubular reactor.

11. The method for producing LDPE according to any one of claims 1 to 10, wherein the LDPE has a melt force of at least 20 mN.

12. The method for producing LDPE according to any one of claims 1 to 11, wherein the LDPE has a Mw / Mn ratio of at least 9.

0.

13. The method for producing LDPE according to any one of claims 1 to 12, wherein the LDPE has a melt flow rate (I2) of 0.1 g / 10 min to 100 g / 10 min.

14. The method for producing LDPE according to any one of claims 1 to 13, wherein the LDPE has a content of 0.9160 g / cm³. 3 Up to 0.9240 g / cm 3 The density.

15. An LDPE resin, said LDPE resin being produced by the method according to any of the preceding claims.

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