Ultraviolet cross-linked ethylene-based polymer

Abstract

Embodiments are directed to an ultraviolet (UV) cross-linked ethylene-based polymer comprising an ethylene-based polymer formed by high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa), free-radical polymerization of ethylene and one or more hydrocarbon-based molecules. Each of the one or more hydrocarbon-based molecules comprises three or more terminal alkene groups. The UV cross-linked ethylene-based polymer has a greater melt elongation relative to an ethylene-based polymer not subjected UV crosslinking. Further embodiments are directed to a process for making the UV cross-linked ethylene-based polymer.

Description

[0001] 86131-WO-PCT / DOW 86131 WO

[0002] 1

[0003] ULTRAVIOLET CROSS-LINKED ETHYLENE-BASED POLYMER

[0004] CROSS-REFERENCE TO RELATED APPLICATIONS

[0005] [1] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 725,662 filed November 27, 2024, the contents of which are incorporated in their entirety herein.

[0006] TECHNICAL FIELD

[0007] [2] Embodiments of the present disclosure generally relate to ethylene-based polymers and specifically relate to ultraviolet (UV) cross-linked ethylene-based polymers.

[0008] BACKGROUND

[0009] [3] High-pressure reactors have been used in industry for making low density polyethylene (LDPE) products for many years. The level of branching in LDPE at given melt index (U) correlates to melt elongation, with higher branching correlating to a higher melt elongation. The level of branching in LDPE is affected by the reactor design and the polymerization conditions used to make the LDPE. But the process conditions required to achieve LDPE with a high level of branching, and thus high melt elongation may result in a final product with a lower crystallinity and with a higher content of a low molecular weight extractable fraction. Branching agents have been used to increase the level of branching in an LDPE under conditions that maintain desirable polymer properties. However, due to processing limitations, only a limited amount of branching agent may be added, thereby limiting the melt elongation increase that may be achieved.

[0010] [4] Thus, there is a need for a modified LDPE having relatively higher branching levels corresponding to a relatively higher melt elongation as compared to a LDPE formed utilizing a branching agent.

[0011] SUMMARY

[0012] [5] The embodiments of the present disclosure meet this need by utilizing ultraviolet (UV) crosslinking. This resulted in a UV cross-linked ethylene-based polymer having a greater melt elongation (e.g., at least 15% greater) relative to an ethylene-based polymer not subjected UV crosslinking. 86131-WO-PCT / DOW 86131 WO

[0013] 2

[0014] [6] In one embodiment, an ultraviolet (UV) cross-linked ethylene-based polymer comprises an ethylene-based polymer formed by high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa), free-radical polymerization of ethylene and one or more hydrocarbon-based molecules. Each of the one or more hydrocarbon-based molecules comprises three or more terminal alkene groups. The UV cross-linked ethylene-based polymer has a greater melt elongation relative to an ethylene-based polymer not subjected UV crosslinking.

[0015] [7] In another embodiment, a process for making an ultraviolet (UV) cross-linked ethylene-based polymer comprises producing an ethylene-based polymer by high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa), free-radical polymerization of ethylene and one or more hydrocarbon-based molecules and crosslinking the ethylene-based polymer via UV exposure for a duration of at least 3 minutes to form the UV cross-linked ethylene-based polymer. Each of the one or more hydrocarbon-based molecules comprises three or more terminal alkene groups. The UV cross-linked ethylenebased polymer has a greater melt elongation relative to an ethylene-based polymer not subjected UV crosslinking.

[0016] [8] Additional features and advantages will be set forth in the detailed description, which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows and the claims.

[0017] [9] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter.

[0018] DETAILED DESCRIPTION

[0019]

[0010] Specific embodiments of the present application will now be described. The disclosure may be embodied in different forms and should not be construed as limited to the embodiments set forth in this disclosure. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art.

[0020]

[0011] DEFINITIONS 86131-WO-PCT / DOW 86131 WO

[0021] 3

[0022]

[0012] Unless stated to the contrary, implicit from the context, or customary in the art, all test methods are current as of the filing date of this disclosure.

[0023]

[0013] Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0024]

[0014] The terms "comprising", "including", "having”, and their derivatives, are not intended to exclude the presence of any additional component, step or procedure, whether the same is specifically disclosed. To avoid any doubt, all compositions claimed through use of the term "comprising" may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term, "consisting essentially of’ excludes from the scope of any succeeding recitation any other component, step or procedure, excepting those that are not essential to operability. The term "consisting of’ excludes any component, step or procedure, not specifically delineated or listed.

[0025]

[0015] Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percentages are based on weight.

[0026]

[0016] The term "ethylene monomer," as used herein, refers to a chemical unit having two carbon atoms with a double bond there between, and each carbon bonded to two hydrogen atoms, wherein the chemical unit polymerizes with other such chemical units to form an ethylene-based polymer composition.

[0027]

[0017] The term “LDPE” may also be referred to as “high-pressure ethylene polymer” or “highly branched polyethylene” and is defined to mean that the polymer is partly or entirely homopolymerized or copolymerized in autoclave or tubular reactors at high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa) with the use of free-radical initiators, such as peroxides (see, for example, U.S. Patent No. 4,599,392, which is hereby incorporated by reference in its entirety). LDPE resins typically have a density in the range of 0.916 g / cm3to 0.930 g / cm3.

[0028]

[0018] The term "hydrocarbon-based molecules comprising three or more terminal alkene groups," (or interchangeably referred to as "hydrocarbon-based molecules") as used herein, 86131-WO-PCT / DOW 86131 WO refers to a chemical component that is a polymer chain composed of only carbon atoms and hydrogen atoms, the polymer chain being branched and having three or more terminal alkene groups.

[0029]

[0019] The term "mixture of hydrocarbon-based molecules," as used herein, refers to two or more hydrocarbon-based molecules, wherein at least two of the molecules differ in structure, property, and / or composition.

[0030]

[0020] The term “terminal double bond,” as used herein, refers to a double bond between two carbon atoms in a polymer chain, wherein one of the carbons in the double-bond is a =CH? group. Terminal double bonds are located at terminal ends of polymer chains and / or at branched ends of polymer chains.

[0031]

[0021] EMBODIMENTS

[0032]

[0022] Embodiments of the present disclosure are directed to ultraviolet (UV) cross-linked ethylene-based polymers comprising an ethylene-based polymer formed by high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa) free-radical polymerization of ethylene and one or more hydrocarbon-based molecules.

[0033]

[0023] Ethylene-based Polymer

[0034]

[0024] The ethylene-based polymer is the polymerization reaction product of ethylene and one or more hydrocarbon-based molecules. Each hydrocarbon-based molecule comprises three or more terminal alkene groups.

[0035]

[0025] In embodiments, each of the hydrocarbon-based molecules (i.e., one or more of the hydrocarbon-based molecules) may comprise Structure I:

[0036] Structure I

[0037]

[0026] In Structure I, R = H or OH; n may be from 3 to 160, such as from 3 to 60, from 3 to 30, from 5 to 160, from 10 to 160, from 20 to 160, from 30 to 160, or from 40 to 160, from 5 to 100, or from 9 to 40; m may be from 0 to 50, such as from 0 to 30, from 1 to 30, from 1 to 50, from 1 to 40, from 1 to 20, from 2 to 20, from 2 to 10, or any subset thereof.

[0038]

[0027] In embodiments, each of the hydrocarbon-based molecules (i.e., one or more of the hydrocarbon-based molecules) may comprise Structure II: 86131-WO-PCT / DOW 86131 WO

[0039] 5

[0040]

[0028] In Structure II, R = H or OH, n may be from 3 to 160, and m may be from 0 to 50; x may be from 0 to 160, and y may be from 0 to 50. For example, n may be from 3 to 160, such as from 3 to 100, from 3 to 30, from 5 to 160, from 10 to 160, from 20 to 160, from 30 to 160, or from 40 to 160, from 5 to 100, or from 9 to 40; m may be from 0 to 50, such as from 0 to 30, from 1 to 50, from 1 to 40, from 1 to 30, from 1 to 20, from 2 to 20, from 2 to 10, or any subset thereof; x may be from 0 to 160, such as from 0 to 140, from 0 to 120, from 0 to 100, from 0 to 80, from 0 to 60, from 0 to 40, from 0 to 20, from 1 to 20, from 1 to 60, from 1 to 100, from 1 to 160, from 10 to 150, from 20 to 140, from 40 to 120, from 60 to 100, or any subset thereof, y may be from 0 to 40, from 0 to 30, from 0 to 20, from 0 to 10, from 1 to 50, from 5 to 50, from 10 to 60, from 20 to 50, from 30 to 50, from 40 to 50, from 10 to 40, or any subset thereof.

[0041]

[0029] The hydrocarbon-based molecules of Structure I, the hydrocarbon-based molecules of Structure II, and / or the overall mixture of hydrocarbon-based molecules may have a molecular weight distribution (MWD = Mw / Mn) from 1.2 to 20, such as from 1.2 to 10, from 1.2 to 5, from 1.2 to 3, from 1.3 to 20, from 1.4 to 20, from 1.5 to 20, from 2 to 20, from 5 to 20, from 10 to 20, from 2 to 18, from 6 to 16, from 8 to 14, or any subset thereof.

[0042]

[0030] In Structure I and Structure II, it should be understood that the hydrocarbon-based molecules may be random copolymers or block copolymers. The individual monomers may, but need not, be arranged in the same order as is shown in Structure I and Structure II. Any polymer which includes both the monomers shown in Structure I (and only those two monomers) is defined by Structure I. Any polymer which includes all four of the monomers shown in Structure II (and only those monomers) is defined by structure II, regardless of the order of the monomers.

[0043]

[0031] In embodiments, a mixture of hydrocarbon-based molecules having the Structure I and / or the Structure II, with differing molecular weights, may be used. The mixture of hydrocarbonbased molecules may comprise hydrocarbon-based molecules of Structure I, Structure II, or a combination thereof. Suitable hydrocarbon-based molecules include those described in detail in U.S. Patent Application Publication Number 2022 / 0017666, the entirety of which is incorporated by reference herein; and include polybutadiene available from Nippon Soda Co., Ltd under the 86131-WO-PCT / DOW 86131 WO

[0044] 6 names PB B- 1000 (a polybutadiene with a number average molecular weight (Mn) of 1200 and at least 85% 1,2-vinyl content), Poly vest 110, available from Evonik Industries (polybutadiene with a number average molecular weight (Mn) of 2600 and only about 1% of 1,2-vinyl content), Polyvest EP MV, available from Evonik Industries (polybutadiene with a number average molecular weight (Mn) of 2000 and only about 61% of 1,2-vinyl content).

[0045]

[0032] In embodiments, the ethylene-based polymer may comprise, in polymerized form, from 95 wt% to 99.95 wt%, from 95 wt% to 99.90 wt%, from 96 wt% to 99.95 wt%, from 96 wt% to 99.90 wt%, from 97 wt% to 99.95 wt%, from 97 wt% to 99.90 wt%, from 98 wt% to 99.95 wt%, from 98 wt% to 99.90 wt%, or any subset thereof, of ethylene, and a reciprocal amount of the mixture of hydrocarbon-based molecules, or from 0.05 wt% to 5 wt%, from 0.05 wt% to 4 wt%, from 0.05 wt% to 3 wt%, from 0.05 wt% to 2 wt%, from 0.1 wt% to 5 wt%, from 0.1 wt% to 4 wt%, from 0.1 wt% to 3 wt%, from 0.1 wt% to 2 wt%, from 0.5 wt% to 5 wt%, from 0.5 wt% to 4 wt%, from 0.5 wt% to 3 wt%, from 0.5 wt% to 2 wt%, from 1 wt% to 5 wt%, from 1 wt% to 4 wt%, from 1 wt% to 3 wt%, from 1 wt% to 2 wt%, or any subset thereof. Weight percent is based on total weight of the ethylene-based polymer.

[0046]

[0033] In embodiments, the ethylene-based polymer may have a density from 0.910 g / cc to 0.940 g / cc, from 0.910 g / cc to 0.935 g / cc, from 0.910 g / cc to 0.930 g / cc, from 0.910 g / cc to 0.925 g / cc, from 0.914 g / cc to 0.940 g / cc, from 0.914 g / cc to 0.935 g / cc, from 0.914 g / cc to 0.930 g / cc, from 0.914 g / cc to 0.925 g / cc, or any subset thereof.

[0047]

[0034] In embodiments, the ethylene-based polymer may have a melt index (E), prior to UV crosslinking, from 0.05 g / 10 min to 200 g / 10 min, from 0.10 g / 10 min to 150 g / 10 min, from 0.10 g / 10 min to 50 g / 10 min, from 0.1 g / 10 min to 10 g / 10 min, from 0.15 g / 10 min to 150 g / 10 min, from 0.15 g / 10 min to 10 g / 10 min, from 0.25 g / 10 min to 150 g / 10 min, from 0.25 g / 10 min to 10 g / 10, or any subset thereof.

[0048]

[0035] In embodiments, the ethylene-based polymer may have an alkenes content from

[0049] 0.05 / 1000 carbons to 3.0 / 1000 carbons, from 0.05 / 1000 carbons to 2.0 / 1000 carbons, from

[0050] 0.05 / 1000 carbons to 1.0 / 1000 carbons, from 0.15 / 1000 carbons to 3.0 / 1000 carbons, from

[0051] 0.15 / 1000 carbons to 2.0 / 1000 carbons, from 0.15 / 1000 carbons to 1.0 / 1000 carbons, from

[0052] 0.3 / 1000 carbons to 3.0 / 1000 carbons, from 0.3 / 1000 carbons to 2.0 / 1000 carbons, from

[0053] 0.3 / 1000 carbons to 1.0 / 1000 carbons, from 0.4 / 1000 carbons to 3.0 / 1000 carbons, from

[0054] 0.4 / 1000 carbons to 2.0 / 1000 carbons, from 0.4 / 1000 carbons to 1.0 / 1000 carbons, or any subset thereof. 86131-WO-PCT / DOW 86131 WO

[0055] 7

[0056]

[0036] In embodiments, the ethylene-based polymer may be a low density polyethylene comprising, in polymerized form, ethylene monomer and the hydrocarbon-based molecules.

[0057]

[0037] The ethylene-based polymer is produced via in-reactor high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa), free-radical polymerization of ethylene and one or more hydrocarbon-based molecules. An exemplary process of making the ethylene-based polymer is described in International Patent Application Publication No. WO 2020 / 112873, which is incorporated herein by reference in its entirety.

[0058]

[0038] In an embodiment, the ethylene-based polymer composition includes a blend component. The blend component is a polymer that does not include the mixture of the hydrocarbon-based molecules.

[0059]

[0039] In an embodiment, the blend component is an ethylene-based polymer that does not include the mixture of the hydrocarbon based molecules. Nonlimiting examples of suitable ethylene-based polymers include only ethylene based polymers like, for example, LDPE or HDPE, ethylene / alpha-olefin copolymers, ethylene / C3-C8 alpha-olefin copolymers, ethylene / C4-C8 alpha-olefin copolymers, and copolymers of ethylene and one or more of the following comonomers: (meth)acrylic acid, (meth)acrylic ester, carbon monoxide, maleic anhydride, vinyl acetate, vinyl propionate, mono esters of maleic acid, diesters of maleic acid, vinyl trialkoxysilane, vinyl trialkyl silane, and any combination thereof.

[0060]

[0040] UV Cross-linked Ethylene-based Polymer

[0061]

[0041] As described herein, the UV cross-linked ethylene-based polymer has a greater melt elongation relative to the ethylene-based polymer not subjected UV crosslinking.

[0062]

[0042] In embodiments, the melt elongation of the UV cross-linked ethylene-based polymer may be at least 15% greater, at least 25% greater, at least 35% greater, at least 45% greater, at least 55% greater, at least 65% greater, at least 75% greater, at least 85% greater, at least 95% greater, or even at least 100% greater than the ethylene-based polymer not subjected to UV crosslinking.

[0063]

[0043] In embodiments, the melt elongation of the UV cross-linked ethylene-based polymer may be at least 5 nM greater, at least 10 nM greater, at least 25 nM greater, at least 50 nM greater, at least 75 nM greater, or even at least 100 nM greater than the ethylene-based polymer not subjected to UV crosslinking.

[0064]

[0044] In embodiments, the UV cross-linked ethylene-based polymer may have a melt elongation greater than or equal to 20 mN, greater than or equal to 25 mN, greater than or 86131-WO-PCT / DOW 86131 WO

[0065] 8 equal to 30 mN, greater than or equal to 35 mN, greater than or equal to 40 mN, greater than or equal to 45 mN, greater than or equal to 50 mN, greater than or equal to 55 mN, greater than or equal to 60 mN, greater than or equal to 65 mN, or even greater than or equal to 70 mN.

[0066]

[0045] While not wishing to be bound by theory, relatively greater melt elongation is indicative of enhanced mechanical properties, dimensional stability, and heat resistance. For example, higher melt elongation may indicate better molecular alignment and packing during the molding process, leading to improved mechanical properties, such as tensile strength, impact resistance, and rigidity. Moreover, rigid articles may need to maintain their shape and dimensions under various conditions. Increased melt elongation may help in achieving a better dimensional stability, reducing warping and deformation. Furthermore, rigid applications may rely on materials that can withstand higher temperatures without losing structural integrity. Increased melt elongation may contribute to better heat resistance, making the material more suitable for demanding environments.

[0067]

[0046] One skilled in the art should appreciate that melt index (I?) correlates to melt elongation, lower melt index (I2) corresponding to greater the melt elongation. However, while not wishing to be bound by theory, after a given UV crosslinking, the melt index (I2) of the thermally cross-linked, ethylene-based polymer may begin to increase.

[0068]

[0047] The UV cross-linked ethylene-based polymer may be used, but not limited to, to form various articles, including monolayer and multilayer films; molded articles, such as blow molded, injection molded, or rotomolded articles; coatings; fibers; and woven or nonwoven fabrics, cables, pipes, green house films, silo bag films, collation shrink films, food packaging films, or foams.

[0069]

[0048] Process for Making an UV Cross-linked Ethylene-based Polymer

[0070]

[0049] In embodiments, a process for making a UV cross-linked ethylene-based polymer comprises producing an ethylene-based polymer and crosslinking the ethylene-based polymer via UV exposure to form the UV cross-linked ethylene-based polymer.

[0071]

[0050] The ethylene-based polymer may be produced by high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa), free-radical polymerization of ethylene and one or more hydrocarbon-based molecules, as described herein.

[0072]

[0051] In embodiments, the crosslinking may comprise exposing the ethylene-based polymer to UV light. UV light helps to promote crosslinking of available double bonds, 86131-WO-PCT / DOW 86131 WO

[0073] 9 thereby achieving the desired increase in melt elongation. In embodiments, the ethylenebased polymer may be formed into an article (e.g., polymer pellets) prior to UV exposure. In embodiments, the UV-enabled crosslinking may occur in ambient air or under inert atmosphere.

[0074]

[0052] In embodiments, the ethylene-based polymer may be exposed to UV for a duration of at least 5 minutes. The duration of the UV exposure may be dependent on the strength of the UV. Additionally, the duration and strength of the UV exposure may help to achieve desired properties. For example, as the duration of UV exposure increases, the melt index (I2) may decrease and the melt elongation may increase.

[0075]

[0053] In embodiments, the duration of the UV exposure may be greater than or equal to 3 minutes and less than or equal to 24 hours, greater than or equal to 3 minutes and less than or equal to 12 hours, greater than or equal to 3 minutes and less than or equal to 6 hours, greater than or equal to 3 minutes and less than or equal to 3 hours, greater than or equal to 3 minutes and less than or equal to 1 hour, greater than or equal to 10 minutes and less than or equal to 24 hours, greater than or equal to 10 minutes and less than or equal to 12 hours, greater than or equal to 10 minutes and less than or equal to 6 hours, greater than or equal to 10 minutes and less than or equal to 3 hours, greater than or equal to 10 minutes and less than or equal to 1 hour, greater than or equal to 3 minutes and less than or equal to 24 hours, greater than or equal to 30 minutes and less than or equal to 12 hours, greater than or equal to 30 minutes and less than or equal to 6 hours, greater than or equal to 30 minutes and less than or equal to 3 hours, greater than or equal to 30 minutes and less than or equal to 1 hour, greater than or equal to 1 hour and less than or equal to 24 hours, greater than or equal to 1 hour and less than or equal to 12 hours, greater than or equal to 1 hour and less than or equal to 6 hours, or even greater than or equal to 1 hour and less than or equal to 3 hours, or any and all sub-ranges formed from any of these endpoints.

[0076]

[0054] In embodiments, the strength of the UV light may be greater than or equal to 3 electron volts and less than or equal to 12 electron volts, greater than or equal to 3 electron volts and less than or equal to 9 electron volts, greater than or equal to 3 electron volts and less than or equal to 6 electron volts, greater than or equal to 6 electron volts and less than or equal to 12 electron volts, greater than or equal to 6 electron volts and less than or equal to 9 electron volts, or even greater than or equal to 9 electron volts and less than or equal to 12 electron volts, or any and all sub-ranges formed from any of these endpoints. 86131-WO-PCT / DOW 86131 WO

[0077] 10

[0078]

[0055] In embodiments, the crosslinking does not include any additional reagents or catalysts, such as silane or peroxide crosslinker.

[0079]

[0056] TEST METHODS

[0080]

[0057] Melt Elongation

[0081]

[0058] “Melt elongation,” as used herein, refers to the measure of the maximum tension applied to a polymer in a melted state, before the polymer breaks. Melt elongation is measured using a GOTTFERT D-Melt instrument (GOTTFERT Werkstoff-Prufmaschinen GmbH, SiemensstraBe 2, 74722 Buchen, Germany). A molten polymer strand is extruded from a standard plastometer barrel at a constant temperature (190 °C) through a standard ASTM D1238 MFR die orifice (height (8.000 ± 0.025 mm) and diameter (2.0955 ± 0.005 mm)) using a weighted piston. The extrudate is pulled through 2 free spinning rollers onto a drum driven by a stepper motor which is ramped over a velocity range during the analysis. The force of the polymer strand pulling up on the force sensor platform mounted tension roller is recorded by the integrated control computer. From a curve fitting function of the acquired force data, the final reported melt elongation value is determined based on a constant velocity ratio of the polymer strand speed versus the die exit speed. Measurement results are reported as melt elongation in milli-Newton (mN). After the melt elongation measurement, the melt index measurement at ASTM conditions as described below is performed with the same charge.

[0082]

[0059] Melt Index

[0083]

[0060] The terms "melt index," or “h,” as used herein, refer to the measure of how easily a thermoplastic polymer flows when in a melted state. Melt index (H) is measured in accordance with ASTM D 1238, Condition 190 °C / 2.16 kg, and is reported in grams eluted per 10 minutes (g / 10 min).

[0084]

[0061] EXAMPLES

[0085]

[0062] By way of example, and not limitation, some embodiments of the present disclosure will now be described in detail by the following examples.

[0086]

[0063] Materials

[0087]

[0064] Polybutadienes (Additive A: Poly vest 110 and Additive B: Poly vest EP MV) were supplied from Evonik Industries. Polybutadiene (Additive C: B-1000) was supplied from Nippon Soda, Co.

[0088]

[0065] Polymerization: Autoclave Reactor 86131-WO-PCT / DOW 86131 WO

[0089] 11

[0090]

[0066] Inventive Examples IE1-IE3

[0091]

[0067] For Inventive Examples IE1-IE3, Additive A, B, or C was loaded into a 316 stainless steel supply vessel and diluted with Isopar™ E to produce a final concentration of 1.7 wt%. This vessel was purged with nitrogen for three hours before use and kept under 70 psig nitrogen pad during operation.

[0092]

[0068] Peroxide initiator tert-butyl peroxyacetate (TPA, 20% by weight solution in ISOPAR™ H) and peroxide initiator di-tert-butyl peroxide (DTBP, 20% by weight solution in ISOPAR™ H) were combined with ISOPAR E in a second 316 stainless steel supply vessel to produce 1500 mass ppm TPA and 415 mass ppm DTBP (a ratio of 4:1 mole TPA / mole DTBP). The vessel was padded and de-padded five times with 70 psig nitrogen before use and kept under nitrogen pad during operation.

[0093]

[0069] Ethylene was injected at 5500 gm / hr and at a pressure of 193 MPa into an agitated (1600 rpm) 300 mL high pressure CSTR reactor with an external heating jacket set to control the internal reactor temperature at 220 °C. Propylene (CTA) was added to the ethylene stream at a pressure of 6.2 MPa and controlled at a rate to produce a final product with a MI of about 4 g / 10 min before the mixture was compressed to 193 MPa and injected into the reactor. The solution of the appropriate additive solution was pumped at a pressure of 193 MPa directly into the reactor via a high pressure pump. The peroxide initiator solution was added directly to the reactor, through the sidewall, at a pressure of 193 MPa at a rate to control the ethylene conversion near 12%.

[0094]

[0070] Comparative Sample CSA

[0095]

[0071] For Comparative Sample CSA, all process conditions were the same as for Inventive Examples IE1-IE3, except for Comparative Sample CSA, no additives were added.

[0096]

[0072] Polymerization: Tubular Reactor

[0097]

[0073] Comparative Sample B CSB

[0098]

[0074] For Comparative Sample CSB, the polymerization was carried out in a tubular reactor with three reaction zones. In each reaction zone, pressurized water was used for cooling and / or heating the reaction medium, by circulating this water through the jacket of the reactor. The inlet-pressure was 222 MPa. Each reaction zone had one inlet and one outlet. Each inlet stream consisted of the outlet stream from the previous reaction zone and / or an added ethylene-rich feed stream. The non-converted ethylene and other gaseous components in the reactor outlet were recycled through a high pressure recycle and a low 86131-WO-PCT / DOW 86131 WO

[0099] 12 pressure recycle, and were compressed and distributed through a booster and a primary and a hyper (secondary) compressors. Organic peroxides (tert-butyl peroxy-2-ethyl hexanoate and di-tert-butyl peroxide) were fed into each reaction zone. Propionaldehyde (PA) was used as a chain transfer agent (CTA) and it was present in each reaction zone inlet, originating from the low pressure and high pressure recycle flows. The fresh PA was added only to the second and third reactions zones in the ratio equivalent to 0.8 and 0.2, respectively. Fresh ethylene was directed towards the first reaction zone.

[0100]

[0075] After reaching the first peak temperature (maximum temperature) in reaction zone 1, the reaction medium was cooled with the aid of the pressurized water. At the outlet of reaction zone 1, the reaction medium was further cooled by injecting cold, ethylene-rich feed and the reaction was re-initiated by feeding an organic peroxide system. This process was repeated at the end of the second reaction zone to enable further polymerization in the third reaction zone. The polymer was extruded and pelletized (about 30 pellets per gram) using a single screw extruder at a melt temperature around 230-250°C. The weight ratio of the ethylene-rich feed streams to the three reaction zones was 1.00:0.80:0.20. The internal process velocity was approximately 12.5, 9, and 11 m / sec for the first, second, and third reaction zones, respectively.

[0101]

[0076] Inventive Example IE4

[0102]

[0077] For Inventive Example IE4, the polymerization was carried out in a tubular reactor with three reaction zones, as discussed above for Comparative Sample B. All process conditions are the same as for Comparative Sample B, except for Inventive Example IE4, Additive C was added to the first zone.

[0103]

[0078] UV Crosslinking

[0104]

[0079] Inventive Examples IE1 - IE3 and Comparative Sample CSA were exposed to UV for 30 min.

[0105]

[0080] UV exposure tests were performed in a UV chamber with a 107 mm UV-C spiral lamp, controlled by the Xenon RC-847 cabinet in Timer mode with settings according to manufacturer instructions: lamp select setting to I, Trig switch OFF, first digit to G, add exposure time and start lamp by pushing the timer switch up to Start position. The pellets were introduced to a petri-dish of 11 cm diameter. A petri-dish cover was used to prevent air exposure due to the high purge flow in the chamber to vent off ozone and cool the lamp. The 86131-WO-PCT / DOW 86131 WO

[0106] 13 petri dish was placed 5 cm below the light source on a 20 cm x 20 cm square Lab-Lift Lifting Platform.

[0107]

[0081] Referring now to Table 1, the melt elongation (in mN) after exposure to UV for the time indicated are shown. The melt elongation increase (in percentage and change) as compared to non-exposure (i.e., time = 0 minutes) is shown. Table 1 also shows the melt index (I?) (in g / 10 min) after exposure to UV. The melt index (I2) change as compared to non-exposure (i.e., time = 0 minutes) is shown.

[0108]

[0082] Table 1

[0109]

[0083] As shown in Table 1, after exposure to UV, Inventive Examples IE1-IE3, UV-cross- linked ethylene-based polymers including polybutadiene, had greater melt elongations as compared to the samples that were not exposed to UV.

[0110]

[0084] As also shown in Table 1, after exposure to UV, Inventive IE1-IE3, UV-cross-linked ethylene-based polymers including polybutadiene, had a greater melt elongation increase as compared to Comparative Sample CSA, a UV-cross-linked ethylene-based polymer lacking polybutadiene.

[0111]

[0085] Referring now to Table 2, the melt elongation (in mN) and melt elongation increase (in percentage and change) of Inventive Example IE4 and Comparative Sample CSB, after exposure to UV for the time indicated, are shown. Table 2 also shows the melt index (I2) (in g / 10 min) and melt index (I2) change after exposure to UV for the time indicated.

[0112]

[0086] Table 2 86131-WO-PCT / DOW 86131 WO

[0113] 14

[0114] 1Measurement capabilities of machine limited to 200 mN.

[0115] 2NM = not measured,

[0116]

[0087] As shown in Table 2, after exposure to UV, Inventive Example IE4, a UV crosslinked ethylene-based polymer including polybutadiene, had greater melt elongations as compared to the sample not exposed to UV. After a certain duration, melt elongations were so high that they could not be measured.

[0117]

[0088] As also shown in Table 2, after exposure to UV, Inventive Example IE4, a UV crosslinked ethylene-based polymer including polybutadiene, had greater melt elongation increases as compared to Comparative Sample CSB, a UV-cross-linked ethylene-based polymer lacking polybutadiene, after the same duration of exposure. 86131-WO-PCT / DOW 86131 WO

[0118] 15

[0119]

[0089] While particular embodiments of the present disclosure have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the disclosure. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this disclosure.

Claims

86131-WO-PCT / DOW 86131 WO16CLAIMS1. An ultraviolet (UV) cross-linked ethylene-based polymer comprising: ethylene-based polymer formed by high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa), free-radical polymerization of ethylene and one or more hydrocarbon-based molecules, each of the one or more hydrocarbon-based molecules comprising three or more terminal alkene groups, wherein the UV cross-linked ethylenebased polymer has a greater melt elongation relative to an ethylene-based polymer not subjected UV crosslinking.

2. The UV cross-linked ethylene-based polymer of claim 1, wherein each of the one or more hydrocarbon-based molecules comprise Structure I:Structure Iwherein R = H or OH, n is from 3 to 160, and m is from 0 to 50.

3. The UV cross-linked ethylene-based polymer of claims 1 or 2, wherein each of the one or more hydrocarbon-based molecules comprise Structure II:Structure IIwherein R = H or OH, n is from 3 to 160, and m is from 0 to 50; x is from 0 to 50, and y is from 0 to 160.

4. The UV cross-linked ethylene-based polymer of claims 2 or 3, wherein a mixture of the one or more hydrocarbon-based molecules based on Structures I or II has a molecular weight distribution (MWD = Mw / Mn) from 1.2 to 20.86131-WO-PCT / DOW 86131 WO175. The UV cross-linked ethylene-based polymer of any one of claims 1-4, wherein the ethylene-based polymer has an alkenes content from 0.05 / 1000 carbons to 3.0 / 1000 carbons, or from 0.07 / 1000 carbons to 2.0 / 1000 carbons, or from 0.1 / 1000 carbons to 1.2 / 1000 carbons.

6. The UV cross-linked ethylene-based polymer of any one of claims 1-5, wherein the ethylene-based polymer composition is a low density polyethylene comprising, in polymerized form, ethylene monomer and the one or more hydrocarbon-based molecules.

7. The UV cross-linked ethylene-based polymer of any one of claims 1-6, wherein the melt elongation of the UV cross-linked ethylene-based polymer is at least 15% greater than the ethylene-based polymer not subjected to UV crosslinking.

8. The UV cross-linked ethylene-based polymer of any one of claims 1-7, wherein the melt elongation of the UV cross-linked ethylene-based polymer is at least 5 mN greater than the ethylene-based polymer not subjected to UV crosslinking.

9. The UV cross-linked ethylene-based polymer of any one of claims 1-8, wherein the melt elongation of the UV cross-linked ethylene-based polymer is greater than or equal to 20 mN.

10. An article comprising the UV cross-linked ethylene-based polymer of any one of claims 1 to 9.

11. A process for making an ultraviolet (UV) cross-linked ethylene-based polymer comprising: producing an ethylene-based polymer by high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa), free-radical polymerization of ethylene and one or more hydrocarbon-based molecules, each of the one or more hydrocarbon-based molecules comprising three or more terminal alkene groups; and crosslinking the ethylene-based polymer via UV exposure for a duration of at least 3 minutes to form the UV cross-linked ethylene-based polymer, wherein the UV cross-linked86131-WO-PCT / DOW 86131 WO18 ethylene-based polymer has a greater melt elongation relative to an ethylene-based polymer not subjected to UV crosslinking.

12. The process of claim 11, wherein the crosslinking does not include silane or peroxide crosslinker.

13. The process of claim 11 or claim 12, wherein the melt elongation of the UV crosslinked ethylene-based polymer is at least 15% greater than the ethylene-based polymer not subjected to UV crosslinking.

14. The process of any one of claims 11-13, wherein the melt elongation of the UV crosslinked ethylene-based polymer is at least 5 mN greater than the ethylene-based polymer not subjected to UV crosslinking.

15. The process of any one of claims 11-14, wherein the melt elongation of the UV crosslinked ethylene-based polymer is greater than or equal to 20 mN.

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