Process for a Reversible Crosslinking Composition

Abstract

The present disclosure provides a process. In one embodiment, the process includes supplying components to a mixing device. These components include (i) a (polar) ethylene-based polymer having a melting temperature Tm, (ii) a free radical initiator having a decomposition temperature Tdecomp, and (iii) 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate). The process includes mixing components (i), (ii), and (iii) in the mixing device at a temperature below the decomposition temperature of the free radical initiator. The process includes forming a crosslinkable polymer composition including the (polar) ethylene-based polymer, the BITEMPS methacrylate, and the free radical initiator.

Description

Technical Field

[0001] Crosslinked olefin polymers (and in particular crosslinked ethylene polymers) are well known in numerous applications due to their excellent mechanical properties, high thermal stability, and outstanding chemical resistance. Unfortunately, crosslinked ethylene polymers (also known as thermoset polymers) cannot be reprocessed and / or recycled due to the presence of a permanent crosslinked network within the ethylene polymer. Thus, the use of crosslinked ethylene polymers is accompanied by associated environmental and sustainability concerns.

[0002] The ability to reprocess and / or recycle crosslinked ethylene polymers has been a longstanding challenge. Thus, the art recognizes the need for crosslinked olefin polymers (and in particular crosslinked ethylene polymers) that can be reprocessed and / or recycled.

Summary of the Invention

[0003] The present disclosure provides a process. In one embodiment, the process includes feeding components to a mixing device. These components include (i) a (polar) ethylene polymer having a melting temperature Tm, (ii) a free radical initiator having a decomposition temperature T decomp and (iii) 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate). The process includes mixing components (i), (ii), and (iii) in the mixing device at a temperature below the decomposition temperature of the free radical initiator. The process includes forming a crosslinkable polymer composition including the (polar) ethylene polymer, BiTEMPS methacrylate, and the free radical initiator.

[0004] Definitions All references to the Periodic Table of the Elements in this specification shall refer to the Periodic Table of the Elements published and copyrighted in 2003 by CRC Press, Inc. Also, any reference to a group shall be to the group reflected in the Periodic Table of the Elements for that element using the IUPAC system for numbering groups. Unless there is a conflicting description, unless it is implied from the context, or unless it is not customary in the art, all parts and percentages are by weight. For the purposes of U.S. patent practice, the contents of any patent, patent application, or publication referenced herein are hereby incorporated by reference in their entirety (or, where equivalent U.S. editions are available, such equivalent U.S. editions are incorporated by reference in like manner).

[0005] The numerical ranges disclosed in this specification include all values (including the boundary values) from the lower limit value to the upper limit value. In the case of a range containing explicit values (for example, a range of 1 or 2 or 3 to 5 or 6 or 7), any sub-range between the two explicit values is included (for example, in the above range of 1 to 7, sub-ranges such as 1 to 2, 2 to 6, 5 to 7, 3 to 7, 5 to 6, etc. are included).

[0006] Unless there is a conflicting description, unless it is implied from the context, or unless it is not customary in the art, all parts and percentages are by weight and all test methods are the latest as of the filing date of this disclosure.

[0007] As used herein, the term "composition" refers to a mixture of materials that includes the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0008] The terms "comprising", "including", "having", and their derivatives are not intended to exclude the presence of any additional constituent, step, or procedure, whether or not specifically disclosed. To avoid any doubt, all compositions claimed through the use of the term "comprising" may, unless inconsistent description exists, contain any additional additive, adjuvant, or compound, whether polymeric or otherwise. In contrast, the term "consisting essentially of" excludes any other constituent, step, or procedure from the scope of any subsequent description, except for those that are not essential to the operation. The term "consisting of" excludes any constituent, step, or procedure not specifically depicted or listed.

[0009] "Ethylene polymer" is a polymer having more than 50 mol% of polymerized ethylene monomer (based on the total amount of polymerizable monomers) and optionally containing at least one comonomer. Ethylene polymers include ethylene homopolymers and ethylene copolymers (meaning units derived from ethylene and one or more comonomers). The terms "ethylene polymer" and "polyethylene" may be used synonymously. Non-limiting examples of ethylene polymers (polyethylene) include low density polyethylene (LDPE) and linear polyethylene. Non-limiting examples of linear polyethylene include linear low density polyethylene (LLDPE), ultra low density polyethylene (ULDPE), very low density polyethylene (VLDPE), ethylene / α-olefin multiblock copolymers (also known as olefin block copolymers (OBC)), substantially linear or linear plastomers / elastomers, and high density polyethylene (HDPE). Generally, polyethylene can be produced using heterogeneous catalyst systems such as Ziegler-Natta catalysts, Group 4 transition metals and metallocenes, non-metallocene metal centers, heterogeneous aryls, heterovalent aryloxy ethers, phosphine imines, and other homogeneous catalyst systems containing ligand structures, and others, in a gas phase, fluidized bed reactor, liquid phase slurry process reactor, or liquid phase solution process reactor. Combinations of heterogeneous catalysts and / or homogeneous catalysts can also be used in either a single reactor or a multi-reactor configuration.

[0010] "Ethylene plastomer / elastomer" means units derived from ethylene and at least one C3-C 10It is a substantially linear or linear ethylene / α-olefin interpolymer containing a uniform short-chain branching distribution comprising units derived from an α-olefin comonomer. The ethylene plastomer / elastomer has a density of 0.854 g / cc to 0.920 g / cc. Non-limiting examples of the ethylene plastomer / elastomer include AFFINITY™ polyolefin plastomer and ENGAGE™ polyolefin elastomer (available from The Dow Chemical Company), EXACT™ plastomer (available from ExxonMobil Chemical), Tafmer™ alpha-olefin copolymer (available from Mitsui), Solumer™ polyolefin elastomer and Supreme™ polyolefin plastomer (available from SK Chemicals Co.), and Lucene™ polyolefin elastomer (available from LG Chem Ltd.).

[0011] "High density polyethylene" (or "HDPE") is an ethylene homopolymer or an ethylene / α-olefin copolymer containing at least one C4-C 10 α-olefin comonomer or C 4- C8α-olefin comonomer, and has a density of 0.940 g / cc, or 0.945 g / cc, or 0.950 g / cc, or 0.953 g / cc to 0.955 g / cc, or 0.960 g / cc, or 0.965 g / cc, or 0.970 g / cc, or 0.975 g / cc, or 0.980 g / cc. HDPE may be a unimodal copolymer or a multimodal copolymer. A "unimodal ethylene copolymer" is an ethylene / C4-C α-olefin copolymer having one distinct peak in gel permeation chromatography (GPC) showing the molecular weight distribution. 10 α-olefin copolymer. A "multimodal ethylene copolymer" is an ethylene / C4-C α-olefin copolymer having at least two distinct peaks in GPC showing the molecular weight distribution. 10It is an α-olefin copolymer. Examples of multimodality include copolymers having two peaks (bimodality) and copolymers having three or more peaks. Non-limiting examples of HDPE include DOW™ high density polyethylene (HDPE) resin (available from The Dow Chemical Company), ELITE™ enhanced polyethylene resin (available from The Dow Chemical Company), CONTINUUM™ bimodal polyethylene resin (available from The Dow Chemical Company), LUPOLEN™ (available from LyondellBasell), and HDPE products from Borealis, Ineos, and ExxonMobil.

[0012] As used herein, the term "linear low density polyethylene" (or "LLDPE") refers to a linear ethylene / α-olefin copolymer containing units derived from ethylene and units derived from at least one C3-C 10 α-olefin, or C4-C8 α-olefin comonomer, having a heterogeneous short chain branch distribution. LLDPE is characterized by having little to no long chain branching, in contrast to conventional LDPE. LLDPE has a density of from 0.910 g / cc to less than 0.940 g / cc. Non-limiting examples of LLDPE include TUFLIN™ linear low density polyethylene resin (available from The Dow Chemical Company), DOWLEX™ polyethylene resin (available from the Dow Chemical Company), and MARLEX™ polyethylene (available from Chevron Phillips).

[0013] The term "low density polyethylene" (or "LDPE") is sometimes referred to as "high pressure ethylene polymer" or "highly branched polyethylene", and is an ethylene homopolymer, typically produced by high pressure free radical polymerization (≥ 100 MPa (e.g., 100 - 400 MPa), in a tubular reactor or autoclave reactor using a free radical initiator). LDPE resins typically have a density in the range of less than 0.915 - 0.940 g / cc. LDPE is different from LLDPE.

[0014] As used herein, an "olefinic polymer" or "polyolefin" is a polymer that contains (based on the total amount of polymerizable monomers) more than 50 mole percent polymerized olefin monomers and may optionally contain at least one comonomer. Non-limiting examples of olefinic polymers include ethylene-based polymers and propylene-based polymers.

[0015] "Polymer" is a compound prepared by polymerizing monomers, whether of the same or different types, which provides a plurality of and / or repeating "units" or "structural units" constituting the polymer in a polymerized form. Thus, the general term "polymer" encompasses the term "homopolymer", which is usually used to refer to a polymer prepared from only one type of monomer, and the term "copolymer", which is usually used to refer to a polymer prepared from at least two types of monomers. It also includes all forms of copolymers, such as random and block copolymers. The terms "ethylene / α-olefin polymer" and "propylene / α-olefin polymer" refer to the above-mentioned copolymers prepared by polymerizing ethylene or propylene and one or more additional polymerizable α-olefin monomers, respectively. Polymers are often referred to as being "made from" one or more specified monomers, such as being "based on" a specified monomer or type of monomer and "containing" a specified monomer content. In this context, it should be noted that the term "monomer" is understood to refer to the polymerized residue of the specified monomer and not to non-polymerized species. Generally, polymers herein are referred to as being based on "units" that are the polymerized form of the corresponding monomers.

[0016] Test Method Compression-molded specimens were formed at a molding pressure of 180 °C and 10 MPa for 5 minutes and then quenched between cooling platens (15 °C to 20 °C) for 2 minutes or as otherwise described herein.

[0017] Measurement of compression set (C-set). Compression set was measured according to ASTM method 395, method B, under the following conditions: A disk of approximately 0.5 inch thickness (t original ) having a diameter of 1 inch from the compression set was pressed to a thickness of 0.375 inch and aged at a temperature of 70 and 100 °C for 20 hours. Thereafter, the sample was released and allowed to stand at room temperature for 30 minutes, and then the thickness was re-measured to obtain t finalIt was set. The compression set (C-set) was calculated by the following equation: C-set = (t original - t final ) / (t original - 0.375) × 100%. The reported C-set was the average of three repeated measurements.

[0018] The density was measured according to ASTM D792, and the results were reported in g / cc at 25°C.

[0019] Dynamic mechanical analysis (DMA). The DMA experiment was carried out using a TA Instruments RSA-G2 Solid Analyzer, and the storage modulus (G’), loss modulus (G”), and damping ratio (tanδ) of the network were measured as functions of temperature and recycling under a nitrogen atmosphere. DMA was operated in tension mode at a frequency of 1 Hz with a vibration strain of 0.03%. Data were collected from room temperature to 160°C at a heating rate of 3°C / min.

[0020] The heat distortion temperature (HDT) was measured using the ASTM D648 method. The temperature at which the sample deformed was reported for loads of 0.455 MPa and 1.82 MPa.

[0021] (Ethylene-based polymer) The melt index (MI or I2) was measured according to ASTM D 1238 under the conditions of 190°C / 2.16 kg, and the results were reported in grams per 10 minutes (g / 10 min). I 21 was measured according to ASTM D 1238 under the conditions of 190°C / 21.6 kg, and the results were reported in grams per 10 minutes (g / 10 min).

[0022] Rheological analysis was performed using a Rubber Process Analyzer (RPA). The rheology of the composition was measured using a rotorless oscillatory shear rheometer, Alpha Technologies RPA 2000 instrument, according to ASTM D6204, under the following test conditions and exceptions. For the analysis, the sample was placed between two mylar films. Rheology was monitored during an initial 60-minute test at 180 °C, 1.0 rad / s, and 7% strain. The elastic torque S’ at the end of the 60-minute (minute) crosslinking process was recorded. Immediately after 60 minutes at 160 °C, a frequency sweep from 0.1 to 300 rad / s was performed on the same sample at 180 °C and 7% strain, then a frequency sweep from 0.1 to 300 rad / s was performed at 190 °C and 7% strain, and then a frequency sweep from 0.1 to 300 rad / s was performed at 230 °C and 7% strain. The dynamic complex viscosity η * , and tan delta were recorded for each frequency sweep. In ASTM D6204, the frequency sweep for unvulcanized rubber is performed before the curing process. In this case, the frequency sweep was performed after the first crosslinking step at 180 °C to evaluate the reversibility of crosslinking. The viscosity temperature reprocessing ratio (or “VRR”) is defined as follows.

[0023] VRR is the ratio of η * at 0.1 rad / s and 230 °C to η * at 0.1 rad / s and 180 °C.

[0024] Tensile measurement at 80 °C. The tensile measurement was carried out on an INSTRON device at an elongation rate of 1 inch / min in accordance with ASTM D1708 standard. The tensile bars were prepared by die-cutting from a compression-molded sheet with a thickness of 1.5 mm. The test was performed in an environmental chamber where the temperature was equilibrated at 80 °C for 30 minutes before the test. Here, the tensile strength was recorded reflecting whether the material has cross-linking characteristics, which is the maximum stress applied before the sample breaks. These parameters were averaged by repeating the tensile measurement three times. Compared with the non-crosslinked part, the crosslinked part typically has significantly higher breaking-point tensile strength.

[0025] Thermomechanical analysis (penetration temperature) was performed on a compression-molded disk with a diameter of 30 mm × thickness of 3.3 mm formed at a molding pressure of 180 °C and 10 MPa for 5 minutes and then air-quenched. The equipment used is a TA Instruments TMA400 thermomechanical analyzer. In the test, a 1.5-mm probe was applied to the surface of the sample disk with a force of 1 N. The temperature was increased from 25 °C at a rate of 5 °C / min. The probe penetration was measured as a function of temperature. The experiment was terminated when the probe penetrated 1000 mm (1 mm) into the sample.

[0026] The Vicat softening point is measured using ASTM D1525. The temperature at which a needle with a flat tip penetrates the sample to a thickness of 1 mm when a load of 10 N is applied is reported.

Mode for Carrying Out the Invention

[0027] The present disclosure provides a process. In one embodiment, the process includes supplying components to a mixing device. These components are (i) a (polar) ethylene-based polymer having a melting temperature Tm and (ii) a decomposition temperature T decompa free radical initiator having, and (iii) 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate). The process includes mixing components (i), (ii), and (iii) in a mixing device at a temperature below the decomposition temperature of the free radical initiator. The process includes forming a crosslinkable polymer composition comprising a (polar) ethylene-based polymer, BiTEMPS methacrylate, and a free radical initiator.

[0028] A. (polar) ethylene-based polymer The composition comprises a (polar) ethylene-based polymer. As used herein, "(polar) ethylene-based polymer" is (i) a polar ethylene-based polymer, (ii) an ethylene-based polymer, or (iii) a combination of (i) and (ii). As used herein, "polar ethylene-based polymer" is an ethylene-based polymer composed of (i) ethylene monomer, (ii) a comonomer containing a heteroatom, and (iii) an optional termonomer (which may or may not contain a heteroatom). In other words, a polar ethylene-based polymer is not a hydrocarbon. The polar ethylene-based polymer has a melt index (MI) of 0.1 g / 10 min to 100 g / 10 min, or 1 g / 10 min to 100 g / 10 min, or 1 g / 10 min to 50 g / 10 min, or 1 g / 10 min to 25 g / 10 min, or 1 g / 10 min to 10 g / 10 min, or 1 g / 10 min to 5 g / 10 min. Non-limiting examples of comonomers having a heteroatom include carbon monoxide, carboxylic acids, esters, alkyl acrylates having 1 to 30 carbon atoms, methacrylate esters having 1 to 30 carbon atoms, vinyl siloxanes having 1 to 16 carbon atoms, and halogens.Non-limiting examples of suitable polar ethylene polymers include ethylene / carboxylic acid copolymers and metal salt partially neutralized ionomers derived therefrom, ethylene / acrylic acid copolymer (EAA), ethylene / methacrylic acid copolymer (EMAA), ethylene / vinyl(trimethoxy)silane copolymer (EVTMS), ethylene / vinyl acetate copolymer (EVA), ethylene / methyl acrylate (EMA), ethylene / ethyl acrylate copolymer (EEA), ethylene / butyl acrylate copolymer (EBA), ethylene / carbon monoxide (ECO), ethylene / glycidyl methacrylate (E / GMA), ethylene / methyl methacrylate copolymer, ethylene / butyl methacrylate copolymer, ethylene / stearyl acrylate copolymer, ethylene / stearyl methacrylate copolymer, ethylene / octyl acrylate copolymer, ethylene / 2-ethylhexyl acrylate copolymer, ethylene / dodecyl acrylate copolymer, polyvinylidene chloride (PVCD), ethylene / maleic anhydride copolymer (EMAH), polyvinyl chloride (PVC), and combinations thereof. Further non-limiting examples of terpolymers include ethylene / carboxylic acid / acrylate terpolymers and metal salt partially neutralized ionomers derived therefrom, ethylene / methyl acrylate / vinyl(trimethoxy)silane terpolymer copolymer (EMAVTMS), ethylene / ethyl acrylate / vinyl(trimethoxy)silane terpolymer copolymer (EEAVTMS), ethylene / butyl acrylate / vinyl(trimethoxy)silane terpolymer copolymer (EBAVTMS), ethylene / methyl acrylate / glycidyl methacrylate (EMAGMA), ethylene / butyl acrylate / glycidyl methacrylate (EBAGMA), ethylene / vinyl acetate / maleic anhydride terpolymer (EEAMAH), ethylene ethyl acrylate / maleic anhydride (EEAMAH) terpolymer, and combinations thereof.

[0029] In one embodiment, the polar ethylene polymer is an ethylene / vinyl acetate copolymer.

[0030] (Polar) ethylene-based polymers can be ethylene-based polymers. As used herein, "ethylene-based polymers" are hydrocarbons and thus are different from polar ethylene-based polymers containing heteroatoms. Ethylene-based polymers can be ethylene homopolymers, ethylene / α-olefin interpolymers, or ethylene / C4-C 20 α-olefin copolymers. In embodiments herein, ethylene-based refers to units derived from ethylene in an amount greater than 50 wt% (based on the total amount of polymerizable monomers) and units derived from one or more α-olefin comonomers in an amount less than 30 wt%. All individual values and subranges of units derived from ethylene in an amount greater than 50 wt% and units derived from one or more α-olefin comonomers in an amount less than 30 wt%. Suitable α-olefin comonomers typically have 20 or fewer carbon atoms. For example, the α-olefin comonomer can have 3 to 10 carbon atoms, or 3 to 8 carbon atoms. Exemplary α-olefin comonomers include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 4-methyl-1-pentene. One or more α-olefin comonomers can be selected, for example, from the group consisting of propylene, 1-butene, 1-hexene, and 1-octene, or alternatively from the group consisting of 1-butene, 1-hexene, and 1-octene, or alternatively from the group consisting of 1-hexene and 1-octene. In some embodiments, the ethylene-based polymer comprises units derived from one or more of 1-octene, 1-hexene, or 1-butene comonomer in an amount greater than 0 wt% to less than 30 wt%.

[0031] The ethylene-based polymer has a melt index (MI) of 0.1 g / 10 min to 100 g / 10 min, or 1 g / 10 min to 100 g / 10 min, or 1 g / 10 min to 50 g / 10 min, or 1 g / 10 min to 25 g / 10 min, or 1 g / 10 min to 10 g / 10 min, or 1 g / 10 min to 5 g / 10 min. In the embodiments of the present specification, the ethylene-based polymer has a density in the range of 0.854 to 0.925 g / cc. All individual values and sub-ranges of 0.854 to 0.925 g / cc are included and disclosed herein. In some embodiments, the ethylene-based composition may have a density of 0.895 to 0.925 g / cc, 0.900 to 0.925 g / cc, 0.900 to 0.920 g / cc, 0.900 to 0.915 g / cc, 0.900 to 0.912 g / cc, 0.900 to 0.911 g / cc, or 0.900 to 0.910 g / cc. In further specific embodiments, the ethylene-based polymer composition may have a density of 0.875 to 0.925 g / cc, 0.890 to 0.925 g / cc, 0.900 to 0.925 g / cc, 0.903 to 0.925 g / cc, or 0.905 to 0.925 g / cc. The density can be measured according to ASTM D792.

[0032] Non-limiting examples of suitable ethylene-based polymers include ethylene / α-olefin interpolymers, high-density polyethylene ("HDPE"), linear low-density polyethylene ("LLDPE"), low-density polyethylene ("LDPE"), and combinations thereof.

[0033] In one embodiment, the ethylene / α-olefin interpolymer is an ethylene / C4-C8 α-olefin copolymer having one, some, or all of the following characteristics: (i) octene comonomer, and / or (ii) a density of 0.860 g / cc to 0.925 g / cc, or 0.880 g / cc to 0.920 g / cc, or 0.899 g / cc to 0.915 g / cc, or 0.899 g / cc to 0.910 g / cc, and / or (iii) A melt index of 0.5 g / 10 min to 100 g / 10 min, or 1 g / 10 min to 30 g / 10 min, or 2 g / 10 min to 20 g / 10 min. Preferred ethylene / C 4- Non-limiting examples of C8α-olefin copolymers include ENGAGE™ 8450 POE, ENGAGE™ 8402 POE, ENGAGE™ 8401 POE, ELITE™ 5815 enhanced polyethylene resin, ELITE™ 5220 enhanced polyethylene resin, or blends thereof.

[0034] In one embodiment, the ethylene-based polymer is an ethylene / α-olefin multiblock copolymer. The term "ethylene / α-olefin multiblock copolymer" refers to an ethylene / C3-C8α-olefin multiblock copolymer consisting of polymerized forms of ethylene and one copolymerizable C3-C8α-olefin comonomer or C4-C8α-olefin comonomer (and optional additives), and the polymer is characterized by a plurality of blocks or segments of two polymerized monomer units having different chemical or physical properties, and the blocks are joined (or covalently bonded) in a linear fashion. That is, the polymer contains chemically distinct units with ends joined to the polymerized ethylenic functional groups. Ethylene / α-olefin multiblock copolymers include block copolymers having two blocks (diblock) and more than two blocks (multiblock). The C3-C8α-olefin is selected from propylene, butene, hexene, and octene. The ethylene / α-olefin multiblock copolymer does not contain styrene (i.e., styrene-free), and / or vinyl aromatic monomers, and / or conjugated dienes, or alternatively excludes them. When referring to the amount of "ethylene" or "comonomer" in the copolymer, this is understood to refer to its polymerized unit. In some embodiments, the ethylene / α-olefin multiblock copolymer has the following formula: (AB) ncan be represented by the formula, where n is at least 1, preferably an integer greater than 1, for example, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, or more; "A" represents a hard block or segment, and "B" represents a soft block or segment. A and B are linked or covalently bonded in a substantially linear manner, or in a linear pattern, as opposed to a substantially branched or substantially star-shaped manner. In other embodiments, the A blocks and B blocks are randomly distributed along the polymer chain. In other words, the block copolymer typically does not have the following structure: AAA-AA-BBB-BB. In one embodiment, the ethylene / α-olefin multiblock copolymer does not have a third type of block containing different comonomers. In another embodiment, each of block A and block B has monomers or comonomers randomly distributed substantially within the block. In other words, neither block A nor block B contains two or more subsegments (or subblocks) of distinct compositions, such as a tip segment having a composition substantially different from the remaining blocks.

[0035] In one embodiment, ethylene constitutes more than half of the molar fraction of the total ethylene / α-olefin multiblock copolymer, i.e., ethylene constitutes at least 50 wt% of the total ethylene / α-olefin multiblock copolymer. More preferably, ethylene comprises at least 60 wt%, at least 70 wt%, or at least 80 wt% together with substantially the remainder of the ethylene / α-olefin multiblock copolymer containing a C3-C8 α-olefin comonomer or a C4-C8 α-olefin comonomer. In one embodiment, the ethylene / α-olefin multiblock copolymer contains 50 wt% to 90 wt% ethylene, or 60 wt% to 85 wt% ethylene, or 65 wt% to 80 wt% ethylene.

[0036] Ethylene / α-olefin multiblock copolymers contain various amounts of "hard" segments and "soft" segments. The "hard" segments are blocks of polymerized units in which ethylene is present in an amount greater than 90 wt%, or 95 wt%, or greater than 95 wt%, or greater than 98 wt%, up to a maximum of 100 wt% based on the weight of the polymer. In other words, the comonomer content (content of monomers other than ethylene) in the hard segments is less than 10 wt%, or 5 wt%, or less than 5 wt%, or less than 2 wt% based on the weight of the polymer, and can be as low as zero. In some embodiments, the hard segments contain all or substantially all of the units derived from ethylene. The "soft" segments are blocks of polymerized units in which the comonomer content (content of monomers other than ethylene) is greater than 5 wt%, or greater than 8 wt%, greater than 10 wt%, or greater than 15 wt% based on the weight of the polymer. In one embodiment, the comonomer content in the soft segments is greater than 20 wt%, greater than 25 wt%, greater than 30 wt%, greater than 35 wt%, greater than 40 wt%, greater than 45 wt%, greater than 50 wt%, or greater than 60 wt%, and can be up to a maximum of 100 wt%.

[0037] The soft segment can be present in the ethylene / α-olefin multiblock copolymer in an amount of 1 wt% to 99 wt% of the total weight of the ethylene / α-olefin multiblock copolymer, or 5 wt% to 95 wt%, 10 wt% to 90 wt%, 15 wt% to 85 wt%, 20 wt% to 80 wt%, 25 wt% to 75 wt%, 30 wt% to 70 wt%, 35 wt% to 65 wt%, 40 wt% to 60 wt%, or 45 wt% to 55 wt% of the total weight of the ethylene / α-olefin multiblock copolymer. Conversely, the hard segment can be present in a similar range. The weight percentages of the soft segment and the hard segment can be calculated based on data obtained from DSC or NMR. Such methods and calculations are disclosed, for example, in U.S. Patent No. 7,608,668, entitled "Ethylene / α-Olefin Block Inter-Polymers," filed on March 15, 2006, in the names of Colin L.P. Shan, Lonnie Hazlitt, et al., and assigned to Dow Global Technologies Inc., the disclosure of which is hereby incorporated by reference in its entirety. In particular, the weight percentages and comonomer content of the hard segment and the soft segment may be determined as described in columns 57 to 63 of U.S. Patent No. 7,608,668.

[0038] Furthermore, the ethylene / α-olefin multiblock copolymer has a PDI (or Mw / Mn) that conforms to a Schultz-Flory distribution rather than a Poisson distribution. This ethylene / α-olefin multiblock copolymer has both a polydisperse block distribution and a polydisperse distribution of block sizes. Thereby, a polymer product having improved distinguishable physical properties is formed. The theoretical advantages of the polydisperse block distribution have already been modeled and considered in Potemkin, Physical Review E (1998) 57(6), pp. 6902-6912, and Dobrynin, J. Chem. Phys. (1997) 107(21), pp. 9234-9238.

[0039] In one embodiment, the ethylene / α-olefin multi-block copolymer has a most probable distribution of block lengths.

[0040] In one embodiment, the ethylene / α-olefin multi-block copolymer is an ethylene / 1-octene multi-block copolymer (consisting only of ethylene and octene comonomers) and has one, some, or all of the following properties: (i) Mw / Mn of 1.7 or 1.8 to 2.2, or 2.5, or 3.5, and / or (ii) a density of 0.860 g / cc or 0.865 g / cc to 0.870 g / cc, or 0.877 g / cc, or 0.880 g / cc, and / or (iii) a melting point Tm of 115 °C, or 118 °C, or 119 °C, or 120 °C to 120 °C, or 123 °C, or 125 °C, and / or (iv) a melt index (MI) of 0.1 g / 10 min or 0.5 g / 10 min to 1.0 g / 10 min, or 2.0 g / 10 min, or 5 g / 10 min, or 10 g / 10 min, and / or (v) 50 to 85 wt% soft segments and 50 to 15 wt% hard segments (based on the total weight of the ethylene / octene multi-block copolymer), and / or (vi) 10 mol%, or 13 mol%, or 14 mol%, or 15 mol% to 16 mol%, or 17 mol%, or 18 mol%, or 19 mol%, or 20 mol% octene in the soft segments, and / or (vii) 0.5 mol%, or 1.0 mol%, or 2.0 mol%, or 3.0 mol% to 4.0 mol%, or 5 mol%, or 6 mol%, or 7 mol%, or 9 mol% octene in the hard segments, and / or (viii) an elastic recovery (Re) of 50% or 60% to 70%, or 80%, or 90% at a deformation rate of 300% / min at 21 °C as measured according to ASTM D 1708, and / or ·1 ​ (ix) Polydispersity distribution of blocks and polydispersity distribution of block sizes (hereinafter referred to as characteristics (i) to (ix) of the multiblock copolymer).

[0041] In one embodiment, the ethylene / α-olefin multiblock copolymer is an ethylene / octene multiblock copolymer. The ethylene / octene multiblock copolymer is sold under the trade name INFUSE™ olefin block copolymer available from The Dow Chemical Company (Midland, Michigan, USA).

[0042] The ethylene / α-olefin multiblock copolymer can be produced via a chain shuttling process such as that described in U.S. Patent No. 7,858,706, which is incorporated herein by reference. In particular, suitable chain shuttling agents and related information are listed in columns 16, line 39 to column 19, line 44. Suitable catalysts are described in column 19, line 45 to column 46, line 19, and suitable cocatalysts are described in column 46, line 20 to column 51, line 28. The process is described throughout the document, and in particular, in column 51, line 29 to column 54, line 56. The process is also described, for example, in U.S. Patent Nos. 7,608,668, 7,893,166, and 7,947,793.

[0043] B. Free radical initiator The composition includes a free radical initiator. In one embodiment, the free radical initiator is an organic peroxide. Non-limiting examples of suitable organic peroxides include bis(1,1-dimethylethyl) peroxide, bis(1,1-dimethylpropyl) peroxide, 2,5-dimethyl-2,5-bis(1,1-dimethylethylperoxy)hexane, 2,5-dimethyl-2,5-bis(1,1-dimethylethylperoxy)hexyne, 4,4-bis(1,1-dimethylethylperoxy)valeric acid, butyl ester, 1,1-bis(1,1-dimethylethylperoxy)-3,3,5-trimethylcyclohexane, benzoyl peroxide, tert-butyl peroxybenzoate, di-tert-amyl peroxide (DTAP), bis(α-t-butyl-peroxyisopropyl) benzene (BIPB), isopropylcumyl t-butyl peroxide, t-butyl cumyl peroxide, di-t-butyl peroxide, 2,5-bis(t-butylperoxy)-2,5-dimethylhexane, 2,5-bis(t-butylperoxy)-2,5-dimethylhex-3-yne, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, isopropylcumyl cumyl peroxide, butyl 4,4-di(tert-butylperoxy)valerate, di(isopropylcumyl) peroxide, dicumyl peroxide, and combinations thereof.

[0044] In one embodiment, the free radical initiator is dicumyl peroxide.

[0045] C. BiTEMPS Methacrylate Disulfide The composition includes 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide, which is synonymously referred to as "BiTEMPS methacrylate" or "BiTEMPS" or "BiT". BiTEMPS methacrylate disulfide has the following Structure 1.

[0046] [Chemistry]

[0047] D. Blend Components In one embodiment, the component includes a blend component. Non-limiting examples of suitable blend components include polyolefins (e.g., polyethylene other than ethylene polymers crosslinked with BiTEMPS methacrylate, and polypropylene), polymers (e.g., polystyrene, ABS, SBS, etc.), and combinations thereof. Non-limiting examples of suitable polyolefins include polyethylene, polypropylene, polybutylene (e.g., polybutene-1), polypentene-1, polyhexene-1, polyoctene-1, polydecene-1, poly-3-methylbutene-1, poly-4-methylpentene-1, polyisoprene, polybutadiene, poly-1,5-hexadiene, interpolymers derived from olefins, interpolymers derived from olefins and other polymers, e.g., polyvinyl chloride, polystyrene, polyurethane, etc., and mixtures thereof.

[0048] E. Additives The component may include one or more optional additives. Non-limiting examples of suitable additives include graft initiators, crosslinking catalysts, blowing agents, blowing agent activators (e.g., zinc oxide, zinc stearate, etc.), co-agents (e.g., triallyl cyanurate), plasticizers, processing oils, processing aids, carbon black, colorants or pigments, stability control agents, nucleating agents, fillers, antioxidants, acid scavengers, ultraviolet (UV) stabilizers, flame retardants, lubricants, processing aids, extrusion aids, and combinations thereof. When present, the total amount of the additive can be more than 0% to 80%, or 0.001% to 70%, or 0.01% to 60%, or 0.1% to 50%, or 0.1% to 40%, or 0.1% to 20%, or 0.1% to 10%, or 0.1% to 5% of the total weight of the composition.

[0049] F. Mixing Component (i) (polar) ethylene polymer, (ii) free radical initiator (peroxide), and (iii) BiTEMPS (and optional additives) are mixed in a mixing device. In one embodiment, the components form a mixture, and the mixture is 70 wt% to 98.5 wt%, or 77 wt% to 98.5 wt% of (polar) ethylene polymer, 0.1 wt% to 10 wt%, or 0.1 wt% to 5 wt%, 0.1 wt% to 3.0 wt%, or 0.1 wt% to 1.5 wt%, or 0.5 wt% to 1.5 wt% of a free radical initiator which is an organic peroxide (such as dicumyl peroxide, etc.), and 1 wt% to 20 wt%, or 1 wt% to 15 wt%, or 2 wt% to 20 wt%, or 2 wt% to 10 wt% of BiTEMPS methacrylate disulfide. It is understood that the aggregate of the polar ethylene polymer, the free radical initiator, and BiTEMPS methacrylate disulfide (and optional additives) is 100 wt% of the mixture.

[0050] The process includes mixing components (i), (ii), and (iii) (and optional additives) in a mixing device at a temperature lower than the decomposition of the free radical initiator (peroxide) to form a crosslinkable polymer composition. The crosslinkable polymer composition includes (i) (polar) ethylene polymer, (ii) free radical initiator (peroxide), and (iii) BiTEMPS (and optional additives). The process ensures that the mixing temperature (and / or the act of mixing) does not initiate the free radical initiator (i.e., does not "kick off"). In this way, the dormant crosslinkable polymer composition does not contain, or is otherwise free of, (i) crosslinking, (ii) grafting, and / or (iii) a combination of (i) and (ii). In other words, the crosslinkable polymer composition has a gel content of 0% or substantially 0%.

[0051] In one embodiment, the crosslinkable polymer composition is produced in a post-reactor process using an extruder. The extruder can be a single-screw extruder, a multi-screw extruder with positive and negative conveying screw elements, and a kneading / mixing plate, paddle or block with lobes.

[0052] In one embodiment, the process includes mixing at a temperature from above the melting temperature of the (polar) ethylene-based polymer to below the decomposition temperature of the free radical initiator.

[0053] In one embodiment, the free radical initiator is dicumyl peroxide and the process includes mixing at a temperature below 140 °C, or from 30 °C to below 140 °C, or from 40 °C to below 140 °C, or from 50 °C to below 140 °C, or from 60 °C to below 140 °C, or from 70 °C to below 140 °C, or from 80 °C to below 140 °C, or from 90 °C to below 140 °C, or from 100 °C to below 140 °C.

[0054] In one embodiment, the mixing (A) melt blending the (polar) ethylene-based polymer at a first temperature over a first process period; (B) adding BiTEMPS and a free radical initiator to the melt-blended ethylene-based polymer of step (A) over a second process period to form a mixture; (C) blending the mixture; (D) forming a crosslinkable polymer composition.

[0055] (The polar) ethylene-based polymer is melt blended in the first period. In one embodiment, the first temperature of process step (A) is at a temperature of ±50 °C, or ±40 °C, or ±30 °C, or ±20 °C of the T of the (polar) ethylene-based polymer. The first temperature is sufficient to effect complete or substantially complete melting of the (polar) ethylene-based polymer. The first temperature is below the decomposition temperature of the free radical initiator. m The first temperature is below the decomposition temperature of the free radical initiator.

[0056] In one embodiment, the free radical initiator is dicumyl peroxide, and the first temperature is from 60 °C to less than 140 °C, or from 80 °C to less than 140 °C, or from 85 °C to 135 °C, or from 85 °C to 130 °C, or from 90 °C to 120 °C. In a further embodiment, the first temperature is from above the Tm of the (polar) ethylene-based polymer to decomp less than the T of the free radical initiator.

[0057] In the second period, BiTEMPS and the free radical initiator are added to and mixed with the molten (polar) ethylene-based polymer. In one embodiment, the first process period ends before the second process period begins.

[0058] In step (C), the mixing temperature remains below the decomposition temperature of the free radical initiator. The free radical initiator does not initiate (i.e., does not "kick off").

[0059] In one embodiment, steps (A)-(D) are carried out in an extruder. Alternatively, steps (A)-(D) are carried out in a batch mixing device such as a Haake™ mixing device.

[0060] The process forms (D) a crosslinkable polymer composition.

[0061] In one embodiment, the process includes collecting the crosslinkable polymer composition. The crosslinkable polymer composition can be collected as a plurality of pellets, as one or more bales, or as a combination of pellets and bales, or otherwise formed.

[0062] The extruder can be operated at a production rate sufficient to produce at least 2,000 pounds per hour of the crosslinkable polymer composition, or at least 2,100 pounds per hour of the crosslinkable polymer composition, or at least 2,200 pounds per hour of the crosslinkable polymer composition.

[0063] The screw speed can be from 200 rpm to 900 rpm. The screw speed is adjusted based on the generated torque and the melting temperature. The barrel temperature in the reaction zone of the extruder can be from 60 °C to less than 140 °C.

[0064] G. Crosslinking In one embodiment, the process includes heating a crosslinkable polymer composition to a crosslinking temperature of from 160 °C to less than 199 °C, or from 180 °C to less than 199 °C, shaping the crosslinkable polymer composition into a preform at the crosslinking temperature, cooling the preform to below the crosslinking temperature, and forming a crosslinked article. In a further embodiment, the crosslinked article includes (i) a (polar) ethylene-based polymer and a bond having Structure 2 formed from 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate). The crosslinked article contains disulfide bonds formed from BiTEMPS methacrylate by a crosslinking reaction, and the disulfide bonds have the following Structure 2.

[0065]

Chemical formula

[0066] The term "P" (and the structure) in Structure 2 above refers to the chain of the polymerized (polar) ethylene (and optional comonomers) of the (polar) ethylene-based polymer. The ethylene-based polymer of the crosslinked composition can be any ethylene-based polymer having an MI of from 0.1 g / 10 min to 100 g / 10 min, as disclosed previously herein.

[0067] In one embodiment, the shaping step is a procedure selected from the group consisting of injection molding, extrusion molding, thermoforming, slush molding, overmolding, insert molding, blow molding, cast molding, tentering, compression molding, and combinations thereof.

[0068] Non-limiting examples of articles suitable for crosslinked (polar) ethylene-based polymer compositions (including the bonds of Structure 2 formed from BiTEMPS methacrylate) include elastic films, elastic fibers, soft-touch items such as toothbrush handles and appliance handles, gaskets and profiles, adhesives (including hot melt adhesives and pressure-sensitive adhesives), footwear (including shoe soles and shoe liners), automotive interior parts and profiles, foam articles (both open-cell and closed-cell foams), impact modifiers for other thermoplastic polymers, such as high-density polyethylene, isotactic polypropylene, or other olefin polymers, coated fabrics, hoses, tubes, overlays, cap liners, flooring materials, and combinations thereof.

[0069] H. Reprocessing BiTEMPS methacrylate is a "dynamic crosslinking agent". The dynamic crosslinking agent BiTEMPS methacrylate enables the formation of a crosslinked network of ethylene-based polymers through disulfide bonds between the chains of ethylene-based polymers. The crosslinked network is formed by an ethylene-based polymer and BiTEMPS methacrylate in the presence of a free radical initiator to form a crosslinked ethylene-based polymer composition. When the crosslinked ethylene-based polymer composition is subjected to a "reprocessing temperature" that is a temperature of 160°C to 230°C, or 160°C to 200°C, the disulfide bonds can be broken, allowing chain mobility and exchange, so the crosslinking is dynamic. At the reprocessing temperature, the disulfide bonds in the crosslinked ethylene-based polymer composition are broken, forming a reprocessable ethylene-based polymer composition. When the reprocessable ethylene-based composition is cooled below the reprocessing temperature, a re-crosslinked ethylene-based polymer composition is formed.

[0070] The dynamic crosslinking agent BiTEMPS methacrylate enables periodic "reprocessing" for the secondary fabrication of new polymer articles. When the crosslinked ethylene-based polymer composition is heated to the reprocessing temperature, the disulfide bonds are broken or otherwise cleaved, allowing the previously crosslinked ethylene-based polymer composition to flow at the reprocessing temperature, forming a "reprocessable ethylene-based polymer composition". Heating to the reprocessing temperature allows bond breakage and polymer chain flow, enabling the ethylene-based composition to be easily reshaped. At the reprocessing temperature, the reprocessable ethylene-based polymer composition is no longer crosslinked, but rather is fluid, now allowing the fluid reprocessable ethylene-based composition (including BiTEMPS methacrylate) to be molded and / or secondarily processed into a new preform or article. Cooling below the "reprocessing temperature" reforms the disulfide bonds, reconstructs the network, and forms a re-crosslinked ethylene-based composition in a new article configuration, returning to the high viscosity (not flowing at room temperature) indicative of the crosslinked network and resistance to mechanical deformation. When the newly formed article of the reprocessable ethylene-based polymer composition is cooled below the reprocessing temperature, the disulfide bonds in the reprocessable ethylene-based polymer composition are reconstructed, and the ethylene-based polymer (including BiTEMPS methacrylate) becomes a re-crosslinked ethylene-based polymer composition assuming the shape of the newly secondarily processed article. Below the reprocessing temperature, the network disulfide bonds are stable, and the re-crosslinked ethylene-based polymer composition exhibits the high viscosity indicative of the crosslinked network and resistance to mechanical deformation. This cycle of crosslinking / reprocessing / re-crosslinking to a new article can be repeated.

[0071] Although not bound by a particular theory, the number of "reprocessing" cycles that are possible using the present crosslinked ethylene-based composition (before competing heat and oxidative permanent crosslinking occur and prevent further reprocessing) can be determined by calculating the ratio of the melt viscosities of the crosslinked ethylene-based polymer composition before and after the reprocessing cycle. For crosslinked ethylene-based polymer compositions that are reprocessable, the ratio of the viscosity after reprocessing to the viscosity before reprocessing is from 0.5 to 5, or from 0.7 to 3, or from 0.9 to 2, or from 0.95 to 1.2.

[0072] Another measurement criterion for monitoring the number of "reprocessing" cycles that are possible using a BiTEMPS methacrylate dynamic crosslinking agent before competing oxidative permanent crosslinking occurs is visual observation. A formed film that has been mechanically deformed is heated to the reprocessing temperature and visually inspected to determine whether the mechanically deformed film recovers to form a stable film.

[0073] In one embodiment, the process includes grinding a crosslinked article to form a ground material and heating the ground material to a reprocessing temperature of 180 °C to 199 °C. The process includes forming the reground material into a reprocessable (polar) ethylene-based polymer composition at the reprocessing temperature and forming the reprocessable (polar) ethylene-based polymer composition into a reprocessed preform at the reprocessing temperature. The process includes cooling the reprocessed preform to below the reprocessing temperature and forming a reprocessed crosslinked article.

[0074] The reprocessed crosslinked article contains disulfide bonds formed from BiTEMPS methacrylate by a re-crosslinking reaction, and the disulfide bonds have Structure 2 below.

[0075]

Chemical Formula

[0076] Articles suitable for the recycled (polar) ethylene polymer composition comprising the bonds of Structure 2 formed from BiTEMPS methacrylate include elastic films, elastic fibers, soft-touch items such as toothbrush handles and instrument handles, gaskets and profiles, adhesives (including hot melt adhesives and pressure sensitive adhesives), footwear (including shoe soles and shoe liners), automotive interior parts and profiles, foam articles (both open cell foams and closed cell foams), impact modifiers for other thermoplastic polymers, such as high density polyethylene, isotactic polypropylene, or other olefin polymers, coated fabrics, hoses, tubes, overlays, cap liners, flooring materials, and combinations thereof.

[0077] In one embodiment, the process includes heating the crosslinked article to a reprocessing temperature of 200 °C to less than 250 °C, or 200 °C to 230 °C, and forming the crosslinked article into a recyclable (polar) ethylene polymer composition at the reprocessing temperature. The process includes shaping the recyclable (polar) ethylene polymer composition into a recycled preform at the reprocessing temperature, cooling the recycled preform to below the reprocessing temperature, and forming a recycled thermoplastic article. The reprocessing temperature of 200 °C to less than 250 °C completely dissociates the disulfide bonds, thereby completely dissociating the bonds between the polymer chains in an irreversible manner. The result is a thermoplastic material.

[0078] 2. Materials 1. Materials The materials used in the comparative sample (CS) and the inventive examples (IE) of the present invention are provided in Table 1 below.

[0079]

Table 1

[0080] 2. Synthesis of BiTEMPS Methacrylate To synthesize BiTEMPS methacrylate, 2,2,6,6 - tetramethyl - 4 - piperidyl methacrylate (8.78 g, 39.0 mmol, supplied by TCI America) is first dissolved in anhydrous petroleum ether (about 90 mL, supplied by Sigma - Aldrich and dried with molecular sieves for 48 hours before use), and cooled to - 70 °C in a dry ice / acetone bath. Then, sulfur monochloride (1.30 g, 9.7 mmol, supplied by Sigma - Aldrich) is dissolved in anhydrous petroleum ether (about 1.25 mL) and added dropwise to the reaction vessel over 30 minutes. The solution is stirred at - 70 °C for an additional 30 minutes and at room temperature for 15 minutes. Next, the reaction solution is poured into a large amount of distilled water and stirred at room temperature overnight to precipitate BiTEMPS methacrylate. The precipitate is collected, vacuum - filtered, and dried in vacuo at 60 °C for 48 hours to obtain BiTEMPS methacrylate shown as Structure 1 below.

[0081]

Chemical formula

[0082] 3. Preparation of the cross - linkable composition (Process A) The polymer composition (parts by weight) and process temperature are listed in Table 2.

[0083]

Table 2

[0084] For each composition in Table 2, the polymer pellets were melt blended with peroxide and BiTEMPS methacrylate at a given weight ratio in an RSI RS5000 equipped with a CAM blade, a RHEOMIX™ 600 batch mixer (commonly referred to as a Haake™ batch mixer available from PolyLabs™) at a set temperature of 30 RPM for 10 minutes. As can be seen from the table, the temperature inside the Haake™ batch mixer was carefully monitored so as not to exceed 140 °C to avoid unwanted reactions. When the temperature exceeded 140 °C, gel formation was observed, which hindered further processing of the sample due to an increase in torque in the Haake™ batch mixer. Gel formation is thought to be the result of the activation of free radical initiators that lead to crosslinking of BiTEMPS with the ethylene-based polymer. At temperatures below 140 °C, this activation was not observed.

[0085] After compounding, a crosslinkable polymer composition containing an ethylene-based polymer, BiTEMPS, and a free radical initiator (DCP) was cooled in a Carver press (cooling platen) at 20000 psi for 4 minutes to produce "crosslinkable pancakes" IE1 - 4 for further testing.

[0086] 4. Preparation of Crosslinked Compositions and Material Properties The crosslinkable pancakes were crosslinked by compression molding. For this process, the crosslinkable pancakes IE1 - 4 were placed in a Carver molding machine model 4095, 60 ton, dual daylight opening size 12 inch × 12 inch, with a temperature range capacity of - 20 °C to 260 °C. The Carver molding machine can produce sheets with a thickness of 2 mm, buttons with a diameter of 1 inch and a thickness of 0.5 inch. For all samples, compression molding was carried out at 180 °C for 15 minutes at 3000 psi. The crosslinked samples were then cooled to 20 °C using a cold press at a pressure of 3000 psi to provide crosslinked plaques IE7 - 9, which were subjected to further physical tests to confirm the crosslinking in the samples reported in Table 3 below.

[0087]

Table 3

[0088] 4. Preparation of Reprocessed Thermoplastic Articles (Process C) After compression molding and cooling, IE8 - 10 from Table 3 were reprocessed under conditions such that the thermoset material was reprocessed into a thermoplastic material. Here, the cross - linked samples IE8 - 10 were cut into strips and fed into a co - rotating twin - screw Xplore MC40 micro - compounder at 50 RPM and a temperature range of 230 °C for 6 minutes. As a comparison, a sample of cross - linked ENGAGE™ 8100 without BiTEMPS (CS1) was also reprocessed on the Xplore MC40 micro - compounder.

[0089]

Table 4

[0090] Samples IE11 - 14 were successfully extruded in a continuous manner. At temperatures higher than 250 °C, side reactions were found to occur, leading to the decomposition of the samples. At temperatures below 200 °C, high torque - strain - suppressing extrusion was achieved. Therefore, a sufficiently high temperature range is 200 °C - 230 °C. IE11 - 14 can be extruded under typical polymer extrusion conditions. The quality of the strands from extrusion was good, with a small surface roughness, but the physical properties were found to be similar to those of the thermoplastic due to the irreversible dissociation of chemical bonds. The extrusion strands of each sample IE11 - 14 were collected and cooled on the surface of a Teflon™ - coated stainless - steel plate.

[0091] It was found that comparative sample 1 (CS) without BiTEMPS could not be reprocessed into a thermoplastic material. In particular, for CS1, high torque was observed in the extruder, and the product was not extrudable at a temperature of 230 °C. The extruded material was produced at a temperature below 200 °C, but the extrudate was severely disrupted and thus not a candidate for pelletization or subsequent reprocessing.

[0092] 5. Process C: Reuse of Portions in Thermoplastic Substances The reprocessability of IE7 - 9 under the conditions for preparing thermosetting materials is also provided herein. Here, the crosslinked plaques IE7 - 9 generated above were reprocessed at a temperature of 160 - 180 °C to form thermoset compression - molded packs. The plaques of IE7 - 9 were cut into small pieces and compression - molded into packs with a diameter of 1.2 inches and a thickness of 0.5 inches at 160 - 180 °C for 15 minutes using a Carver molding machine as described in Table 5 below.

[0093]

Table 5

[0094] As can be seen in Table 5, each of the samples IE15 - 17 of the present invention reprocessed at a temperature of 160 - 180 °C produced a material having thermosetting properties that could be reformed in part. On the other hand, the comparative sample (CS2) reprocessed at a temperature of 230 °C resulted in no thermosetting properties. The tensile strength of CS2 at 80 °C decreased by 80% compared to IE15 molded at 180 °C. Therefore, it was found that CS2 molded at 230 °C no longer had thermosetting properties due to the irreversible cleavage of disulfide bonds.

[0095] The present disclosure is not limited to the embodiments and examples included herein, and is particularly intended to include modified forms of those embodiments, including parts of the embodiments and combinations of elements of different embodiments, to the extent that they fall within the scope of the following claims.

Claims

1. It is a process, (i) A (polar) ethylene-based polymer having a melting temperature Tm, (ii) Decomposition temperature T ｄｅｃｏｍｐ A free radical initiator having, (iii) 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate) and a component comprising these components are supplied to a mixing device. In the mixing apparatus, components (i), (ii), and (iii) are mixed at a temperature below the decomposition temperature of the free radical initiator. A process comprising forming a crosslinkable polymer composition comprising the (polar) ethylene polymer, the BiTEMPS methacrylate, and the free radical initiator.

2. The process according to claim 1, comprising mixing the (polar) ethylene polymer at a temperature between the melting temperature of the (polar) ethylene polymer and the decomposition temperature of the free radical initiator.

3. The process according to claim 1, wherein the free radical initiator is dicumyl peroxide, and the process comprises mixing at a temperature of less than 140°C.

4. The process according to claim 3, wherein the process includes mixing at a temperature of 80°C to less than 140°C.

5. The process according to claim 1, comprising collecting the crosslinkable polymer composition as pellets, one or more bales, and combinations of pellets and one or more bales.

6. The crosslinkable polymer composition is heated to a crosslinking temperature of 160°C to less than 199°C, The process involves forming the crosslinkable polymer composition into a preform at the aforementioned crosslinking temperature, Cooling the preform to below the crosslinking temperature, A process according to any one of claims 1 to 5, comprising forming a crosslinked article.

7. The aforementioned crosslinked article, (i) The (polar) ethylene polymer and, (ii) The process according to claim 6, comprising a bond having structure 2. 【Chemistry 1】

8. The aforementioned crosslinked article is crushed to form a crushed material, The pulverized material is heated to a reprocessing temperature of 180°C to 199°C, At the aforementioned reprocessing temperature, the refracted material is formed into a reprocessable (polar) ethylene-based polymer composition. The reprocessable (polar) ethylene-based polymer composition is molded into a reprocessed preform at the aforementioned reprocessing temperature. The reprocessed preform is cooled to a temperature below the reprocessing temperature, The process according to claim 6, comprising forming a reprocessed crosslinked article.

9. The crosslinked article is heated to a reprocessing temperature of 200°C to less than 250°C, At the aforementioned reprocessing temperature, the crosslinked article is formed into a reprocessable (polar) ethylene-based polymer composition. At the aforementioned reprocessing temperature, the reprocessable ethylene-based polymer composition is molded into a reprocessed preform. The reprocessed preform is cooled to a temperature below the reprocessing temperature, The process according to claim 6, comprising forming a reprocessed thermoplastic article.

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