Polar ethylene polymer containing a reversible crosslinking agent

Abstract

The present disclosure provides a crosslinkable polymer composition. In one embodiment, the crosslinkable polymer composition includes a polar ethylene-based polymer, a free radical initiator, and 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate). The present disclosure provides a crosslinked composition. In one embodiment, the crosslinked composition includes a polar ethylene-based polymer and 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate).

Description

Technical Field

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

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

Summary of the Invention

[0003] The present disclosure provides a crosslinkable polymer composition. In one embodiment, the crosslinkable polymer composition comprises a polar ethylene polymer, a free radical initiator, and 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate).

[0004] The present disclosure provides a crosslinked composition. In one embodiment, the crosslinked composition comprises a polar ethylene polymer and 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate).

[0005] Definitions All references to the Periodic Table of the Elements in this specification shall refer to the Periodic Table copyrighted and published 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 otherwise indicated, unless otherwise implied from the context, or unless otherwise customary in the art, all parts and percentages are by weight. For purposes of U.S. patent practice, the contents of any patent, patent application, or publication referenced in this specification are hereby incorporated by reference in their entirety (or their equivalent U.S. versions are so incorporated by reference).

[0006] 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, the above range of 1 to 7 includes sub-ranges such as 1 to 2, 2 to 6, 5 to 7, 3 to 7, 5 to 6, etc.).

[0007] Unless otherwise indicated, unless otherwise implied from the context, or unless otherwise 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.

[0008] 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.

[0009] 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 include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless there is a contradictory description. In contrast, the term "consisting essentially of" excludes any other constituent, step, or procedure from the scope of any subsequent description, except those that are not essential to the operation. The term "consisting of" excludes any constituent, step, or procedure not specifically depicted or recited.

[0010] "Ethylene-based polymer" is a polymer that contains more than 50 mole percent of polymerized ethylene monomer (based on the total amount of polymerizable monomers) and optionally may contain at least one comonomer. Ethylene-based polymers include ethylene homopolymers and ethylene copolymers (meaning units derived from ethylene and one or more comonomers). The terms "ethylene-based polymer" and "polyethylene" may be used synonymously. Non-limiting examples of ethylene-based 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), multi-component ethylene copolymers (EPE), ethylene / α-olefin multi-block 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, homogeneous catalyst systems containing ligand structures such as non-metallocene metal centers, heteroaryl, heterovalent aryloxy ethers, phosphine imines, etc., and others, in gas phase, fluidized bed reactor, liquid phase slurry process reactor, or liquid phase solution process reactor. Combinations of heterogeneous and / or homogeneous catalysts can also be used in either a single reactor or dual reactor configuration.

[0011] "Heteroatom" means an atom other than carbon and hydrogen. Heteroatoms can be non-carbon atoms from Groups IV, V, VI, and VII of the periodic table. Non-limiting examples of heteroatoms include F, N, O, P, B, S, and Si.

[0012] A "hydrocarbon" is a compound containing only hydrogen atoms and carbon atoms. A "hydrocarbonyl" (or "hydrocarbonyl group") is a hydrocarbon having a valence (typically monovalent). Hydrocarbons can have a linear structure, a cyclic structure, or a branched structure.

[0013] 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 optionally can contain at least one comonomer. Non-limiting examples of olefinic polymers include ethylene-based polymers and propylene-based polymers.

[0014] A "polymer" is a compound prepared by polymerizing monomers, whether of the same kind or different kinds, which provides a plurality of and / or repeating "units" or "structural units" that constitute the polymer in a polymerized form. Thus, the general term "polymer" encompasses the term "homopolymer" which is commonly used to refer to a polymer prepared from only one kind of monomer, and the term "copolymer" which is commonly used to refer to a polymer prepared from at least two kinds of monomers. Also included are all forms of copolymers such as random, block, etc. The terms "ethylene / α-olefin polymer" and "propylene / α-olefin polymer" refer to the above-described 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" which are the polymerized form of the corresponding monomers.

[0015] Test method Density is measured according to ASTM D792, and the results are reported in g / cc at 25 °C.

[0016] Differential scanning calorimetry (DSC) is performed using a Mettler Toledo DSC822e differential scanning calorimeter to measure the thermal properties including the peak and end melting temperatures and crystallinity of the polymer and crosslinked composition (network polymer). The network materials tested for most polymers are the as-synthesized materials before compression molding. A heating rate of 10 °C / min and a cooling rate of -40 °C / min were adapted for all measurements in the temperature range of -60 °C to 160 °C.

[0017] Dynamic mechanical analysis (DMA). The DMA experiment is performed using a TA Instruments RSA-G2 Solid Analyzer to measure the storage modulus (E’), loss modulus (E’’), and damping ratio (tanδ) of the network as a function of temperature and reuse under a nitrogen atmosphere. DMA operates in tension mode at a frequency of 1 Hz with a vibration strain of 0.03%. Data is collected from room temperature to 160 °C at a heating rate of 3 °C / min.

[0018] The melt index (MI or I2) of (ethylene-based polymers) is measured according to ASTM D 1238 under the conditions of 190 °C / 2.16 kg, and the results are reported in grams per 10 minutes (g / 10 min).

Embodiments for Carrying Out the Invention

[0019] The present disclosure provides a crosslinkable polymer composition. In one embodiment, the crosslinkable polymer composition comprises a polar ethylene-based polymer, a free radical initiator, and 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate).

[0020] A. Polar ethylene polymer The crosslinkable polymer composition contains a polar ethylene-based polymer. 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 ter monomer (which may or may not contain a heteroatom). In other words, the 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 acid, ester, alkyl acrylate having 1 to 30 carbon atoms, methacrylate ester having 1 to 30 carbon atoms, vinyl siloxane having 1 to 16 carbon atoms, and halogen. Non-limiting examples of suitable polar ethylene-based polymers include ethylene / carboxylic acid copolymer 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.Additional 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 copolymers (EMAVTMS), ethylene / ethyl acrylate / vinyl(trimethoxy)silane terpolymer copolymers (EEAVTMS), ethylene / butyl acrylate / vinyl(trimethoxy)silane terpolymer copolymers (EBAVTMS), ethylene / methyl acrylate / glycidyl methacrylate (EMAGMA), ethylene / butyl acrylate / glycidyl methacrylate (EBAGMA), ethylene / vinyl acetate / maleic anhydride terpolymers (EEAMAH), ethylene ethyl acrylate / maleic anhydride (EEAMAH) terpolymers, and combinations thereof.

[0021] In one embodiment, the polar ethylene-based polymer is an ethylene / vinyl acetate copolymer.

[0022] B. Free Radical Initiator The crosslinkable composition contains 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-dimethylhexine-3, 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.

[0023] In one embodiment, the free radical initiator is dicumyl peroxide.

[0024] C.BiTEMPS methacrylate disulfide The crosslinkable polymer composition contains 2,2,6,6-tetramethyl-4-piperidyl methacrylate, which is synonymously called "BiTEMPS methacrylate" or "BiTEMPS" or "BiT". BiTEMPS methacrylate disulfide has the following Structure 1.

[0025] [Chemical]

[0026] In one embodiment, the crosslinkable composition comprises 70 wt% to 98.5 wt%, or 77 wt% to 98.5 wt% of a polar ethylene polymer, 0.5 wt% to 10 wt%, or 0.5 wt% to 5 wt%, or 0.5 wt% to 3.0 wt%, or 0.5 wt% to 1.5 wt%, or 1.5 wt% to 3.0 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 3 wt% to 20 wt%, or 3 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) amounts to 100 wt% of the crosslinkable polymer composition.

[0027] The present disclosure provides a crosslinked composition. The crosslinkable polymer composition is melt blended at a temperature of 100°C to 250°C, or 120°C to 200°C, or 120°C to 180°C, or 120°C to 160°C to cause a crosslinking reaction to form the crosslinked composition. In one embodiment, the crosslinked composition comprises a polar ethylene polymer and 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate). The crosslinked composition contains disulfide bonds formed from BiTEMPS methacrylate by the crosslinking reaction, and the disulfide bonds have the following Structure 2.

[0028] [Chemical]

[0029] The term "P" (and structure) in the above structure 2 refers to the chain of polymerized ethylene (and comonomers having heteroatoms) of a polar ethylene-based polymer. The polar ethylene-based polymer of the crosslinked composition can be any polar ethylene-based polymer having an MI of 0.1 g / 10 min to 100 g / 10 min, as disclosed previously herein. Non-limiting examples of suitable polar ethylene-based 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.As further non-limiting examples of terpolymers, ethylene / carboxylic acid / acrylate terpolymers and partially neutralized metal salt ionomers derived therefrom, ethylene / methyl acrylate / vinyl(trimethoxy)silane terpolymer copolymers (EMAVTMS), ethylene / ethyl acrylate / vinyl(trimethoxy)silane terpolymer copolymers (EEAVTMS), ethylene / butyl acrylate / vinyl(trimethoxy)silane terpolymer copolymers (EBAVTMS), ethylene / methyl acrylate / glycidyl methacrylate (EMAGMA), ethylene / butyl acrylate / glycidyl methacrylate (EBAGMA), ethylene / vinyl acetate / maleic anhydride terpolymers (EEAMAH), ethylene ethyl acrylate / maleic anhydride (EEAMAH) terpolymers, and combinations thereof may be mentioned.

[0030] In one embodiment, the polar ethylene-based polymer is an unused polar ethylene-based polymer. As used herein, an "unused polar ethylene-based polymer" is a polar ethylene-based polymer that has not been subjected to a crosslinking reaction. In other words, the term "unused polar ethylene-based polymer" refers to the polar ethylene-based polymer present in the crosslinking composition before the polar ethylene-based polymer is crosslinked with BiTEMPS methacrylate. The unused polar ethylene-based polymer is the polar ethylene-based polymer before crosslinking, and the crosslinking composition contains the same polar ethylene-based polymer that was unused but is now crosslinked with BiTEMPS methacrylate. In this way, the unused polar ethylene-based polymer serves as a baseline for evaluating the properties of the crosslinking composition. The crosslinking composition has (i) a storage modulus value E' at 140 °C that is greater than the storage modulus value E' of the unused polar ethylene-based polymer at 140 °C, and (ii) a tan delta value at 60 °C that is less than the tan delta value of the unused polar ethylene-based polymer at 60 °C, and (iii) a tan delta value at 140 °C that is less than the tan delta value of the unused polar ethylene-based polymer at 140 °C.

[0031] In one embodiment, the crosslinked composition comprises 80% to 97% by weight of a polar ethylene-based polymer and 3% to 20% by weight of BiTEMPS methacrylate, and the aggregate of the polar ethylene-based polymer and BiTEMPS methacrylate (and optional additives) is 100% by weight of the crosslinked composition. The crosslinked composition (i) a storage modulus value E' at 60°C greater than 1 MPa, and (ii) a storage modulus value E' at 140°C greater than 0.1 MPa, and (iii) a tan delta value at 60°C less than 0.17, and (iv) a tan delta value at 140°C less than 0.62.

[0032] D. Blend Components In one embodiment, the crosslinkable composition and / or the crosslinked composition comprises blend components. Non-limiting examples of suitable blend components include ethylene vinyl acetate (EVA), polyolefins (e.g., polyethylene other than a polar ethylene-based polymer 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.

[0033] In one embodiment, the polyolefin is a homopolymer such as polyethylene, polypropylene, polybutylene, poly(1-pentene), poly(3-methyl-1-butene), poly(4-methyl-1-pentene), polyisoprene, polybutadiene, poly(1,5-hexadiene), poly(1-hexene), poly(1-octene), and poly(1-decene).

[0034] Non-limiting examples of polyethylene (other than polar ethylene polymers crosslinked with BITEMPS methacrylate) suitable as blend components include ultra-low density polyethylene (ULDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), high molecular weight high density polyethylene (HMW-HDPE), ultra high molecular weight polyethylene (UHMW-PE), and combinations thereof. Non-limiting examples of polypropylene include low density polypropylene (LDPP), high density polypropylene (HDPP), high-melt strength polypropylene (HMS-PP), and combinations thereof. In one embodiment, the blend component is high-melt strength polypropylene (HMS-PP), low density polyethylene (LDPE), or a combination thereof.

[0035] E. Additives The crosslinkable composition and / or the crosslinked composition may contain 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.), auxiliaries (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 additives 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.

[0036] In one embodiment, the crosslinkable composition and / or the crosslinked composition contains an antioxidant. Non-limiting examples of suitable antioxidants include aromatic or hindered amines, such as alkyldiphenylamine, phenyl-α-naphthylamine, alkyl- or aralkyl-substituted phenyl-α-naphthylamine, alkylated p-phenylenediamine, tetramethyl-diaminodiphenylamine, etc., phenols, such as 2,6-di-t-butyl-4-methylphenol, 1,3,5-trimethyl-2,4,6-tris(3’,5-di-t-butyl-4,-hydroxybenzyl)benzene, tetrakis[(methylene(3,5-di-t-butyl1-4-hydroxyhydrocinnamate)]methane (e.g., IRGANOX™ 1010 (Ciba Geigy, New York)), acryloyl-modified phenol, octadecyl-3,5-di-t-butyl-4-hydroxycinnamate (e.g., IRGANOX™ 1076 commercially available from Ciba Geigy), phosphites and phosphonites, hydroxylamines, benzofuranone derivatives, and combinations thereof. When used, the amount of the antioxidant in the composition can be more than 0 to 5% by weight, 0.0001 to 2.5% by weight, or 0.001 to 1% by weight, or 0.001 to 0.5% by weight of the total weight of the composition.

[0037] In one embodiment, the crosslinkable composition and / or the crosslinked composition includes a UV stabilizer. Non-limiting examples of suitable UV stabilizers include benzophenone, benzotriazole, aryl ester, oxanilide, acrylic ester, formamidine, carbon black, hindered amine, nickel quencher, hindered amine, phenolic antioxidant, metal salt, zinc compound, and combinations thereof. When used, the amount of the UV stabilizer can be more than 0 to 5 wt%, or 0.01 wt% to 3 wt%, or 0.1 wt% to 2 wt%, or 0.1 wt% to 1 wt% of the total weight of the composition.

[0038] In one embodiment, the crosslinkable composition and / or the crosslinked composition includes a colorant or pigment. Non-limiting examples of suitable colorants or pigments include inorganic pigments such as metal oxides such as iron oxide, zinc oxide, and titanium dioxide, mixed metal oxides, carbon black, organic pigments such as anthraquinone, ansanthrone, azo, and monoazo compounds, arylamide, benzimidazolone, BONA lake, diketopyrrolo-pyrrole, dioxazine, disazo compound, diarylide compound, flavanthrone, indanthrone, isoindolinone, isoindoline, metal complex, monoazo salt, naphthol, b-naphthol, naphthol AS, naphthol lake, perylene, perinone, phthalocyanine, pyranthrone, quinacridone, and quinophthalone, and combinations thereof. When used, the amount of the colorant or pigment in the composition can be more than 0 to 10 wt%, or 0.1 wt% to 5 wt%, or 0.25 wt% to 2 wt% of the total weight of the composition.

[0039] In one embodiment, the crosslinkable and / or crosslinking compositions comprise a filler. Non-limiting examples of suitable fillers include talc, calcium, carbonate, chalk, calcium sulfate, clay, kaolin, silica, glass, fumed silica, mica, wollastonite, feldspar, aluminum silicate, calcium silicate, alumina, hydrated alumina such as alumina trihydrate, glass microspheres, barite, wood flour, glass fiber, carbon fiber, marble flour, cement flour, magnesium oxide, magnesium hydroxide, antimony oxide, zinc oxide, barium sulfate, titanium dioxide, titanates, and combinations thereof.

[0040] In one embodiment, the filler is barium sulfate, talc, calcium carbonate, silica, glass, glass fiber, alumina, titanium dioxide, or mixtures thereof. In further embodiments, the filler is talc, calcium carbonate, barium sulfate, glass fiber, or mixtures thereof. If used, the amount of filler in the composition can be from greater than 0 to 80 wt.%, or from 0.1 to 60 wt.%, or from 0.5 to 40 wt.%, or from 1 to 30 wt.%, or from 10 to 40 wt.% of the total weight of the composition.

[0041] In one embodiment, the crosslinkable composition and / or crosslinking composition includes a lubricant. Non-limiting examples of suitable lubricants include fatty alcohols and their dicarboxylic acid esters, fatty acid esters of short-chain alcohols, fatty acids, fatty acid amides, metal soaps, oligomeric fatty acid esters, fatty acid esters of long-chain alcohols, montan wax, polyethylene wax, polypropylene wax, natural and synthetic paraffin waxes, fluoropolymers, and combinations thereof. When used, the amount of lubricant in the composition can be greater than 0 wt.% to 5 wt.%, or 0.1 to 4 wt.%, or 0.1 to 3 wt.% of the total weight of the composition.

[0042] In one embodiment, the crosslinkable composition and / or the crosslinked composition includes an antistatic agent. Non-limiting examples of suitable antistatic agents include conductive fillers (e.g., carbon black, metal particles, and other conductive particles), fatty acid esters (e.g., glycerol monostearate), ethoxylated alkylamines, diethanolamide, ethoxylated alcohols, alkyl sulfonates, alkyl phosphates, quaternary ammonium salts, alkyl betaines, and combinations thereof. When used, the amount of the antistatic agent in the composition can be more than 0 wt% to 5 wt%, or 0.01 to 3 wt%, or 0.1 to 2 wt% of the total weight of the composition.

[0043] In one embodiment, the crosslinkable composition and / or the crosslinked composition includes a blowing agent. A "blowing agent" is a substance capable of generating a cellular structure in the composition via a foaming process. The blowing agent is used to foam the crosslinked composition. Non-limiting examples of suitable blowing agents include inorganic physical blowing agents such as air, argon, nitrogen, carbon dioxide, argon, helium, oxygen, and neon, and aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, and n-hexane, cycloaliphatic hydrocarbons such as cyclohexane and cyclopentane, halogenated hydrocarbons such as chlorofluoromethane, trifluoromethane, 1,1-difluoroethane, 1,1,1,2-tetrafluoroethane, methyl chloride, ethyl chloride, and methylene chloride, and organic physical blowing agents such as dialkyl ethers such as dimethyl ether, diethyl ether, and methyl ethyl ether.

[0044] Non-limiting examples of suitable organic blowing agents include aliphatic hydrocarbons having 1 to 6 carbon atoms, aliphatic alcohols having 1 to 3 carbon atoms, and fully and partially halogenated aliphatic hydrocarbons having 1 to 4 carbon atoms. Non-limiting examples of suitable aliphatic hydrocarbons include methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, etc. Non-limiting examples of suitable aliphatic alcohols include methanol, ethanol, n-propanol, and isopropanol. Non-limiting examples of suitable fully and partially halogenated aliphatic hydrocarbons include fluorocarbons, chlorocarbons, and chlorofluorocarbons. Non-limiting examples of suitable fluorocarbons include fluorinated methyl, perfluoromethane, fluorinated ethyl, 1,1-difluoroethane (HFC152a), 1,1,1-trifluoroethane (HFC-143a), 1,1,1,2-tetrafluoroethane (HFC-134a), pentafluoroethane, difluoromethane, perfluoroethane, 2,2-difluoropropane, 1,1,1-trifluoropropane, perfluoropropane, dichloropropane, difluoropropane, perfluorobutane, perfluorocyclobutane. Non-limiting examples of suitable partially halogenated chlorocarbons and chlorofluorocarbons include methyl chloride, methylene chloride, ethyl chloride, 1,1,1-trichloroethane, 1,1-dichloro-1-fluoroethane (HCFC-141b), 1-chloro-1,1-difluoroethane (HCFC-142b), 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123), and 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124). Non-limiting examples of suitable fully halogenated chlorofluorocarbons include trichloromonofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), trichlorotrifluoroethane (CFC-113), 1,1,1-trifluoroethane, pentafluoroethane, dichlorotetrafluoroethane (CFC-114), chloroheptafluoropropane, and dichlorohexafluoropropane.Non-limiting examples of suitable chemical blowing agents include azodicarbonamide, azodiisobutyronitrile, benzenesulfonohydrazide, 4,4-oxybeneznesulfonyl-semicarbazide, p-toluenesulfonyl-semicarbazide, barium azodicarboxylate, N,N'-dimethyl-N,N'-dinitrosoterephthalamide, and trihydrazinotriazine.

[0045] BiTEMPS methacrylate is a "dynamic crosslinking agent". The dynamic crosslinking agent BiTEMPS methacrylate enables the formation of a crosslinked network with a polar ethylene-based polymer by disulfide bonds between the chains of the polar ethylene-based polymer (in the presence of a free radical initiator) to form a crosslinked polar ethylene-based polymer composition. When the crosslinked polar ethylene-based polymer composition is subjected to a "reprocessing temperature" that is a temperature of 100°C to 250°C, or 120°C to 200°C, or 120°C to 180°C, or 120°C to 160°C, the disulfide bonds can be broken, enabling chain mobility and exchange, so the crosslinking is dynamic. At the reprocessing temperature, the disulfide bonds in the crosslinked polar ethylene-based polymer composition are broken, forming a reprocessable polar ethylene-based polymer composition. When the reprocessable polar ethylene-based composition is cooled below the reprocessing temperature, a re-crosslinked polar ethylene-based polymer composition is formed.

[0046] The dynamic crosslinking agent BiTEMPS methacrylate enables periodic "reprocessing" for the secondary fabrication of new polymer articles. When a crosslinked polar ethylene-based polymer composition is heated to the reprocessing temperature, the disulfide bonds are broken or otherwise cleaved, allowing the previously crosslinked polar ethylene-based polymer composition to flow at the reprocessing temperature and form a "reprocessable polar ethylene-based polymer composition". Heating to the reprocessing temperature enables bond breakage and polymer chain flow, allowing the polar ethylene-based composition to be easily reshaped. At the reprocessing temperature, the reprocessable polar ethylene-based polymer composition is no longer crosslinked but rather is fluid, now enabling the molding and / or secondary processing of the fluid reprocessable polar ethylene-based polymer composition (including BiTEMPS methacrylate) into a new preform or article. Cooling below the "reprocessing temperature" reforms the disulfide bonds, reconstructs the network, and forms a re-crosslinked polar ethylene-based composition with a new article configuration, returning to the high viscosity (non-flowing at room temperature) indicative of the crosslinked network and resistance to mechanical deformation. When the newly formed article of the reprocessable polar ethylene-based polymer composition is cooled below the reprocessing temperature, the disulfide bonds in the reprocessable polar ethylene-based polymer composition are reconstructed, and the polar ethylene-based polymer (including BiTEMPS methacrylate) becomes a re-crosslinked polar ethylene-based polymer composition assuming the shape of the newly secondary-processed article. Below the reprocessing temperature, the network disulfide bonds are stable, and the re-crosslinked polar 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 and secondary processing into new articles can be repeated.

[0047] Although not bound by a particular theory, the number of “reprocessing” cycles that are possible using the present crosslinked polar 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 polar ethylene-based polymer composition before and after the reprocessing cycle. For a crosslinked polar ethylene-based polymer composition that is reprocessable, the ratio of the Mooney viscosity after reprocessing to the Mooney 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.

[0048] 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. This measurement criterion for reprocessability is shown in Table 2 below.

[0049] The present disclosure provides a process. In one embodiment, the process includes heating a first article to a reprocessing temperature. The first article is composed of a crosslinked polar ethylene-based polymer composition comprising (i) a polar ethylene-based polymer and (ii) 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate). The process includes forming, at the reprocessing temperature, the first article into a reprocessable polar ethylene-based polymer composition. The process includes molding, at the reprocessing temperature, the reprocessable polar ethylene-based composition into a reprocessed preform. The process includes cooling the reprocessed preform to below the reprocessing temperature to form a second article composed of a re-crosslinked polar ethylene-based polymer composition comprising (i) a polar ethylene-based polymer and (ii) BiTEMPS methacrylate, the second article being different from the first article.

[0050] In one embodiment, the forming 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, and combinations thereof.

[0051] Non-limiting examples of articles (first article and second article) suitable for the present crosslinked / re-crosslinked polar ethylene-based polymer (including BiTEMPS methacrylate) compositions 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 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, liners, cap liners, flooring materials, and combinations thereof.

[0052] By way of example and not limitation, several embodiments of the present disclosure will now be described in detail in the following examples.

[0053] [[ID=X]]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.

[0054] [Table 1]

[0055] 1. 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 overnight at room temperature to precipitate BiTEMPS methacrylate. The precipitate is collected, vacuum filtered, and dried under vacuum at 60 °C for 48 hours to obtain BiTEMPS methacrylate shown as Structure 1 below.

[0056]

Chemical formula

[0057] 2. Preparation of the crosslinked composition Weigh out appropriate masses of the starting materials, a polymer pellet (polar ethylene-based polymer), a crosslinking agent (BiTEMPS methacrylate), and a radical initiator (DCP) separately on a chemical balance (typically, 2 g of polymer, 0.1 g of crosslinking agent, and 0.02 g of radical initiator). Before synthesis, load the polymer of interest, heat it above its melt transition point, and wash out impurities from the cup of a Dynisco (formerly Atlas) Laboratory Mixing Molder (LMM) by mixing for 3 - 5 minutes. After washing out the polymer fragments, add the bulk polymer pellet and the powder mixture of the crosslinking agent and radical initiator to the cup with a spatula. Add the starting materials in doses such that they are uniformly distributed throughout the cup before mixing. Additionally, add three steel balls (about 5 mm in diameter) uniformly to the cup to mimic the extrusion process during melt-state mixing. Next, raise the temperature of the LMM above the melt transition point of the polymer and mix the starting materials at this temperature at 120 rpm (maximum rotational speed) for 3 - 5 minutes to ensure homogenization of the melt-state components while minimizing radical initiation. For Polymer 1, this mixing temperature is 100 °C. After this homogenization, raise the temperature of the LMM to 160 °C to initiate the radical initiation and crosslinking agent grafting process. Mix for about 20 minutes at this temperature. During mixing, manually cycle the rotor of the LMM up and down periodically to promote homogenization of the blend. After mixing for 20 minutes, stop the mixing and remove the crosslinked polymer blend from the cup with a spatula.

[0058] Cut the crosslinked composition (network blend) into small pieces and compression mold it into a film having dimensions of 50 mm in length, 25 mm in width, and 0.65 mm in thickness in a PHI press (Model 0230C-X1) at 160 °C and 8 MPa for 30 minutes to obtain a first molded sample. Cut the film into millimeter-sized small pieces and compression mold it under the same conditions to obtain a second molded sample, and repeat this procedure again to obtain a third molded sample. Cut strips from each sample film for dynamic mechanical analysis (DMA).

[0059] 3. Polymer 1

[0060] [Table 2]

[0061] Table 2 shows E’ and tanδ at both 60 °C and 140 °C for the IE1 crosslinked composition (network formulation) of Polymer 1. The E’ value of the network polymer at 60 °C is equal (same order of magnitude) to the E’ value of each of the unused polymers within the range of experimental uncertainty. Depending on the changes in dynamic crosslinking and crystallinity after processing compared to the unused polymer, the E’ value at this temperature may be slightly lower (due to a decrease in crystallinity, the E’ decreases below the melting transition point despite the improvement due to crosslinking) or slightly higher (the crystallinity is slightly affected and the E’ is improved by crosslinking). The continuous molded article of the IE1 crosslinked composition containing Polymer 1 at this temperature shows an E’ value that is approximately equal (same order of magnitude) to the E’ values of each of the unused polymers and the first molded sample within the range of experimental uncertainty.

[0062] At 140 °C, the E’ value of the IE1 crosslinked composition (network polymer) is greater than the E’ value of each of the unused Polymer 1. This is because the unused Polymer 1 does not have network characteristics that would give a large E’ value (>0.1 MPa) above the melting transition point. The continuous molded article of the IE1 polymer crosslinked composition at 140 °C shows an E’ value that is approximately equal (same order of magnitude) to the E’ value of the first molded sample or slightly higher (due to additional crosslink formation during processing) within the range of experimental uncertainty.

[0063] Consistent with a greater presence of crosslinking in the network material, the tanδ values at both 60 °C and 140 °C are smaller for the IE1 crosslinked composition (network formulation) compared to its respective virgin counterpart polymer 1. Additionally, these values are maintained for samples continuously molded at both 60 °C and 140 °C. The IE1 crosslinked compositions presented in Table 2 demonstrate that polymer 1 not only gives a substantial dynamic network response (above 1 MPa at 60 °C and above 0.1 MPa at 140 °C) upon crosslinking, but is also reprocessable and recovers its E’ and tanδ values after continuous compression molding cycles. Processable comparative samples do not achieve a substantial network response, and comparative samples that give a substantial network response cannot be reprocessed because permanent crosslinking rather than sufficient dynamic crosslinking is present and do not recover their thermomechanical properties after processing.

[0064] Table 2 provides the thermal properties (melting range and crystallinity) of virgin polymer 1 (comparative sample) and the IE1 crosslinked composition (network formulation) of the examples of the present invention determined by DSC. Reactive crosslinking reduces the order of the crystalline structure formed during processing after cooling, slightly reducing the crystallinity of the network polymer and also reducing its melting peak and end point compared to the virgin counterpart polymer 1 (comparative sample).

[0065] The present disclosure is not limited to the embodiments and examples contained herein, and is particularly intended to include modified forms of those embodiments, including portions 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. A crosslinkable polymer composition comprising: a polar ethylene-based polymer; a free radical initiator; 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate), and a crosslinkable polymer composition.

2. The crosslinkable polymer composition according to claim 1, wherein the polar ethylene-based polymer has a melt index of 0.1 g / 10 min to 100 g / 10 min.

3. The crosslinkable polymer composition according to claim 1 or 2, wherein the polar ethylene-based polymer is selected from the group consisting of ethylene / carboxylic acid copolymer, ethylene / acrylic acid copolymer (EAA), ethylene / vinyl acetate copolymer (EVA), ethylene / ethyl acrylate copolymer (EEA), ethylene / butyl acrylate copolymer (EBA), 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, polyvinyl chloride (PVC), and combinations thereof.

4. The crosslinkable polymer composition according to any one of claims 1 to 3, wherein the free radical initiator is an organic peroxide.

5. 70% to 98.5% by weight of the polar ethylene-based polymer; 0.5% to 10.0% by weight of the free radical initiator; 1% to 20% by weight of BiTEMPS methacrylate, and a crosslinkable polymer composition according to any one of claims 1 to 4.

6. The crosslinkable polymer according to any one of claims 1 to 5, wherein the free radical initiator is dicumyl peroxide.

7. A crosslinked composition comprising: a polar ethylene-based polymer; 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate), and a crosslinked composition.

8. The crosslinked composition according to claim 7, wherein the crosslinked composition comprises a bond of Structure 2. 【Chemical 1】

9. 80% to 99% by weight of a polar ethylene-based polymer having a melt index of 0.1 g / 10 min to 100 g / 10 min; The crosslinked composition according to claim 7 or 8, comprising 20% by weight to 1% by weight of the BiTEMPS methacrylate.

10. The crosslinked composition according to any one of claims 7 to 9, wherein the polar ethylene-based polymer is selected from the group consisting of an ethylene / carboxylic acid copolymer, an ethylene / acrylic acid copolymer (EAA), an ethylene / vinyl acetate copolymer (EVA), an ethylene / ethyl acrylate copolymer (EEA), an ethylene / butyl acrylate copolymer (EBA), an ethylene / methyl methacrylate copolymer, an ethylene / butyl methacrylate copolymer, an ethylene / stearyl acrylate copolymer, an ethylene / stearyl methacrylate copolymer, an ethylene / octyl acrylate copolymer, an ethylene / 2-ethylhexyl acrylate copolymer, an ethylene / dodecyl acrylate copolymer, polyvinyl chloride (PVC), and combinations thereof.

11. The polar ethylene-based polymer is an unused polar ethylene-based polymer before the crosslinked composition is crosslinked, The crosslinked composition is (i) a storage elastic modulus value E' at 140°C that is greater than the storage elastic modulus value E' of the unused polar ethylene-based polymer at 140°C, (ii) a tan delta value at 60°C that is less than the tan delta value of the unused polar ethylene-based polymer at 60°C, (iii) a tan delta value at 140°C that is less than the tan delta value of the unused polar ethylene-based polymer at 140°C, and has the crosslinked composition according to any one of claims 7 to 10.

12. Comprising 3% by weight to 20% by weight of BiTEMPS methacrylate, The crosslinked composition is (i) a storage elastic modulus value E' at 60°C that is greater than 1 MPa, (ii) a storage elastic modulus value E' at 140°C that is greater than 0.1 MPa, (iii) a tan delta value at 60°C that is less than 0.17, (iv) a tan delta value at 140°C that is less than 0.62, and has the crosslinked composition according to any one of claims 7 to 11.

13. A process, A first article, heating the first article, which is composed of a crosslinked polar ethylene-based polymer composition comprising (i) a polar ethylene-based polymer and (ii) 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate), to a reprocessing temperature; At the reprocessing temperature, forming the first article into a reprocessable polar ethylene-based polymer composition; At the reprocessing temperature, shaping the reprocessable polar ethylene-based composition into a reprocessed preform; Cooling the reprocessed preform to below the reprocessing temperature to form a second article composed of a re-crosslinked polar ethylene-based polymer composition composed of (i) the polar ethylene-based polymer and (ii) the BiTEMPS methacrylate, the second article being different from the first article. A process comprising forming.

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