Polar ethylene-based polymers with reversible cross-linking agents

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 a 2, 2, 6, 6-tetramethyl-4-piperidinyl methacrylate disulfide (BiTEMPS methacrylate). The present disclosure provides a crosslinking composition. In one embodiment, the crosslinking composition comprises a polar ethylene-based polymer; and 2, 2, 6, 6-tetramethyl-4-piperidinyl methacrylate disulfide (BiTEMPS methacrylate), and a method for preparing the same.

Description

Background Art

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

[0002] The ability to reprocess and / or recycle crosslinked ethylene polymers has been a long-standing challenge. Accordingly, the art recognizes a need for crosslinked olefin polymers (particularly 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 vinyl polymer, a free radical initiator, and 2,2,6,6-tetramethyl-4-piperidinyl methacrylate disulfide (BiTEMPS methacrylate).

[0004] The present disclosure provides a cross-linked composition. In one embodiment, the cross-linked composition comprises a polar vinyl polymer; and 2,2,6,6-tetramethyl-4-piperidinyl methacrylate disulfide (BiTEMPS methacrylate).

[0005] definition

[0006] All references to the Periodic Table of the Elements herein shall refer to the Periodic Table of the Elements published and copyrighted by CRC Press, Inc. in 2003. Furthermore, any reference to one or more groups shall be to the one or more groups reflected in such Periodic Table of the Elements using the IUPAC system for numbering groups. Unless stated to the contrary, implied by the context, or customary in the art, all parts and percentages are by weight. For purposes of U.S. patent practice, any patent, patent application, or publication referred to herein is incorporated herein by reference in its entirety (or its equivalent U.S. version is so incorporated by reference).

[0007] The numerical range disclosed herein includes all values ​​from the lower limit to the upper limit and including the lower limit and the upper limit. For a range containing clear values ​​(e.g., a range of 1 or 2, or 3 to 5, or 6, or 7), any sub-range between any two clear values ​​is included (e.g., the above range 1 to 7 includes 1 to 2; 2 to 6; 5 to 7; 3 to 7; 5 to 6; etc.).

[0008] Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percentages are by weight and all test methods are current as of the filing date of this disclosure.

[0009] The term "composition" as used herein refers to a mixture of materials which comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0010] The terms "comprising," "including," "having," and derivatives thereof are not intended to exclude the presence of any additional components, steps, or procedures, whether or not specifically disclosed. For the avoidance of any doubt, all compositions claimed through use of the term "comprising" may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term "consisting essentially of excludes from the scope of any subsequent recitation any other components, steps, or procedures, except those that are not essential to operability. The term "consisting of excludes any ingredient, step, or procedure not specifically recited or listed.

[0011] "Ethylene polymers" are polymers containing more than 50 mole percent of polymerized ethylene monomers (based on the total amount of polymerizable monomers) and optionally may contain 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 polymers" and "polyethylene" are used interchangeably. 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), multi-component ethylene copolymers (EPE), ethylene / alpha-olefin multi-block copolymers (also referred to as olefin block copolymers (OBC)), substantially linear or linear plastomers / elastomers, and high-density polyethylene (HDPE). Generally speaking, polyethylene can be produced in a gas phase fluidized bed reactor, a liquid phase slurry reactor or a liquid phase solution reactor using a heterogeneous catalyst system (such as a Ziegler-Natta catalyst), a homogeneous catalyst system comprising a Group 4 transition metal and a ligand structure (such as a metallocene, a non-metallocene metal center, a heteroaryl, an isovalent aryloxy ether, a phosphinimine, etc.). Combinations of heterogeneous and / or homogeneous catalysts can also be used in a single reactor or dual reactor configuration.

[0012] A "heteroatom" is an atom other than carbon or hydrogen. A heteroatom can be a non-carbon atom from Group IV, Group V, Group VI, and Group VII of the periodic table. Non-limiting examples of heteroatoms include: F, N, O, P, B, S, and Si.

[0013] A "hydrocarbon" is a compound containing only hydrogen and carbon atoms. A "hydrocarbon group" (or "hydrocarbon group") is a hydrocarbon having a valence (usually a single valence). A hydrocarbon may have a straight chain structure, a cyclic structure, or a branched structure.

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

[0015] "Polymer" is a compound prepared by polymerizing monomers of the same or different types that provide multiple and / or repeating "units" or "monomer units" constituting the polymer in a polymerized form. Therefore, the general term polymer covers the term homopolymer, which is usually used to refer to polymers prepared from only one type of monomer, and the term copolymer, which is usually used to refer to polymers prepared from at least two types of monomers. The general term also covers all forms of copolymers, such as random copolymers, block copolymers, etc. The terms "ethylene / α-olefin polymer" and "propylene / α-olefin polymer" represent copolymers prepared by polymerizing ethylene or propylene and one or more other polymerizable α-olefin monomers, respectively, as described above. It should be noted that although polymers are often referred to as being "made of" one or more specific monomers, "based on" a specific monomer or monomer type, "containing" a specific monomer content, etc., in this context, the term "monomer" should be understood to refer to the polymerized remains of a specific monomer, rather than an unpolymerized species. In general, polymers herein refer to "units" based on the polymerized form of the corresponding monomer.

[0016] Test Method

[0017] Density is measured according to ASTM D792, with results reported in g / cc at 25°C.

[0018] Differential Scanning Calorimetry (DSC) was performed using a Mettler Toledo DSC822e Differential Scanning Calorimeter to measure thermal properties of virgin polymers and crosslinked compositions (network polymers), including peak and endpoint melting temperatures and crystallinity. The network materials tested for most polymers were as-synthesized materials prior to compression molding. A 10°C / min heating rate and a -40°C / min cooling rate were applied to all measurements in the temperature range of -60°C to 160°C.

[0019] Dynamic Mechanical Analysis (DMA). DMA experiments were performed using a TA Instruments RSA-G2 solid analyzer to measure the storage modulus (E'), loss modulus (E"), and damping ratio (tan δ) of the networks as a function of temperature and recovery under a nitrogen atmosphere. The DMA was operated in tension mode with a frequency of 1 Hz and an oscillating strain of 0.03%. Data were collected from room temperature to 160°C at a heating rate of 3°C / min.

[0020] Melt index (MI or I2) (for ethylene-based polymers) is measured according to ASTM D 1238, Condition 190°C / 2.16 kg, with results reported in grams per 10 minutes (g / 10 min). DETAILED DESCRIPTION

[0021] The present disclosure provides a crosslinkable polymer composition. In one embodiment, the crosslinkable polymer composition comprises a polar vinyl polymer, a free radical initiator, and 2,2,6,6-tetramethyl-4-piperidinyl methacrylate disulfide (BiTEMPS methacrylate).

[0022] A. Polar vinyl polymers

[0023] The crosslinkable polymer composition comprises a polar ethylene polymer. As used herein, a "polar ethylene polymer" is an ethylene polymer consisting of (i) ethylene monomer, (ii) a comonomer containing heteroatoms and (iii) an optional terionomer (which may or may not contain heteroatoms). In other words, the polar ethylene polymer is not a hydrocarbon. The melt index (MI) of the polar ethylene polymer is from 0.1 g / 10min to 100 g / 10min, or from 1 g / 10min to 100 g / 10min, or from 1 g / 10min to 50 g / 10min, or from 1 g / 10min to 25 g / 10min, or from 1 g / 10min to 10 g / 10min, or from 1 g / 10min to 5 g / 10min. Non-limiting examples of comonomers having heteroatoms include carbon monoxide, carboxylic acids, esters, alkyl acrylates having 1 to 30 carbon atoms, methacrylates having 1 to 30 carbon atoms, vinyl siloxanes having 1 to 16 carbon atoms, and halogens. Non-limiting examples of suitable polar vinyl polymers include ethylene / carboxylic acid copolymers and ionomers partially neutralized with metal salts derived therefrom, ethylene / acrylic acid copolymers (EAA), ethylene / methacrylic acid copolymers (EMAA), ethylene / vinyl (trimethoxy) silane copolymers (EVTMS), ethylene / vinyl acetate copolymers (EVA), ethylene / methyl acrylate (EMA), ethylene / ethyl acrylate copolymers (EEA), ethylene / butyl acrylate copolymers (EBA), ethylene / carbon monoxide (ECO), ethylene / glycidyl methacrylate (E / GMA), ethylene / methyl methacrylate copolymers, ethylene / butyl methacrylate copolymers, ethylene / octadecyl acrylate copolymers, ethylene / octadecyl methacrylate copolymers, ethylene / octyl acrylate copolymers, ethylene / 2-ethylhexyl acrylate copolymers, ethylene / dodecyl acrylate copolymers, polyvinyl dichloride (PVCD), ethylene / maleic anhydride copolymers (EMAH), polyvinyl chloride (PVC), and combinations thereof. Additional non-limiting examples of terpolymers include ethylene / carboxylic acid / acrylate terpolymers and partially neutralized ionomers with metal salts derived therefrom, ethylene / methyl acrylate / vinyl (trimethoxy) silane terpolymers (EMAVTMS), ethylene / ethyl acrylate / vinyl (trimethoxy) silane terpolymers (EEAVTMS), ethylene / butyl acrylate / vinyl (trimethoxy) silane terpolymers (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.

[0024] In one embodiment, the polar vinyl polymer is an ethylene / vinyl acetate copolymer.

[0025] B. Free Radical Initiators

[0026] The crosslinkable composition comprises 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)pentanoic 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-tert-butylperoxyisopropyl)benzene ("BIPB"); isopropylcumyl tert-butyl peroxide; tert-butylcumyl peroxide; di-tert-butyl peroxide; 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane; 2,5-bis(tert-butylperoxy)-2,5-dimethylhexyne-3,1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane; isopropylcumylcumyl peroxide; butyl 4,4-di(tert-butylperoxy)valerate; di(isopropylcumyl) peroxide; diisopropylbenzene peroxide, and combinations thereof.

[0027] In one embodiment, the free radical initiator is dicumyl peroxide.

[0028] C. BiTEMPS methacrylate disulfide

[0029] The crosslinkable polymer composition comprises 2,2,6,6-tetramethyl-4-piperidinyl methacrylate, interchangeably referred to as "BiTEMPS methacrylate" or "BiTEMPS" or "BiT." BiTEMPS methacrylate disulfide has the following structure 1.

[0030]

[0031] In one embodiment, the crosslinkable polymer composition comprises:

[0032] 70 wt % to 98.5 wt %, or 77 wt % to 98.5 wt % of a polar ethylene polymer;

[0033] 0.5 wt % to 10 wt %, or 0.5 wt % to 5 wt %, or 0.5 wt % to

[0034] 3.0 wt %, or 0.5 wt % to 1.5 wt %, or 1.5 wt % to 3.0 wt % of a free radical initiator, the free radical initiator being an organic peroxide (e.g. diisopropyl peroxide)

[0035] benzene); and

[0036] 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 polar vinyl polymer, free radical initiator and BiTEMPS methacrylate disulfide (and optional additives) totals 100 wt % of the crosslinkable polymer composition.

[0037] The present disclosure provides a cross-linked composition. The cross-linkable 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 initiate a cross-linking reaction and form a cross-linked composition. In one embodiment, the cross-linked composition comprises a polar ethylene polymer and 2,2,6,6-tetramethyl-4-piperidinyl methacrylate disulfide (BiTEMPS methacrylate). The cross-linked composition contains a disulfide bond formed by BiTEMPS methacrylate through a cross-linking reaction, and the disulfide bond has the following structure 2.

[0038]

[0039] The term (and structure) "P" in Structure 2 above refers to the chains of polymerized ethylene (and comonomers with heteroatoms) of the polar ethylene polymer. The polar ethylene polymer of the crosslinked composition can be any polar ethylene polymer having a MI of 0.1 g / 10 min to 100 g / 10 min as previously disclosed herein. Non-limiting examples of suitable polar vinyl polymers include ethylene / carboxylic acid copolymers and ionomers partially neutralized with metal salts derived therefrom, ethylene / acrylic acid copolymers (EAA), ethylene / methacrylic acid copolymers (EMAA), ethylene / vinyl (trimethoxy) silane copolymers (EVTMS), ethylene / vinyl acetate copolymers (EVA), ethylene / methyl acrylate (EMA), ethylene / ethyl acrylate copolymers (EEA), ethylene / butyl acrylate copolymers (EBA), ethylene / carbon monoxide (ECO), ethylene / glycidyl methacrylate (E / GMA), ethylene / methyl methacrylate copolymers, ethylene / butyl methacrylate copolymers, ethylene / octadecyl acrylate copolymers, ethylene / octadecyl methacrylate copolymers, ethylene / octyl acrylate copolymers, ethylene / 2-ethylhexyl acrylate copolymers, ethylene / dodecyl acrylate copolymers, polyvinyl dichloride (PVCD), ethylene / maleic anhydride copolymers (EMAH), polyvinyl chloride (PVC), and combinations thereof. Additional non-limiting examples of terpolymers include ethylene / carboxylic acid / acrylate terpolymers and partially neutralized ionomers with metal salts derived therefrom, ethylene / methyl acrylate / vinyl (trimethoxy) silane terpolymers (EMAVTMS), ethylene / ethyl acrylate / vinyl (trimethoxy) silane terpolymers (EEAVTMS), ethylene / butyl acrylate / vinyl (trimethoxy) silane terpolymers (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.

[0040] In one embodiment, the polar vinyl polymer is a native polar vinyl polymer. As used herein, a "native polar vinyl polymer" is a polar vinyl polymer that has not yet undergone a crosslinking reaction. In other words, the term "native polar vinyl polymer" refers to the polar vinyl polymer present in the crosslinked composition before the polar vinyl polymer is crosslinked with BiTEMPS methacrylate. The native polar vinyl polymer is the polar vinyl polymer before crosslinking, and the crosslinked composition contains the same polar vinyl polymer that is native but now crosslinked with BiTEMPS methacrylate. In this way, the native polar vinyl polymer is used as a benchmark for evaluating the properties of the crosslinked composition. The crosslinked composition has

[0041] (i) a storage modulus value E' at 140°C that is greater than the storage modulus value E' of the native polar ethylene polymer at 140°C;

[0042] (ii) a tan δ value at 60°C that is less than the tan δ value at 60°C of the native polar ethylene polymer; and

[0043] (iii) a tan δ value at 140°C that is less than the tan δ value at 140°C of the native polar ethylene polymer.

[0044] In one embodiment, the crosslinked composition comprises 80 wt % to 97 wt % of a polar vinyl polymer and 3 wt % to 20 wt % of BiTEMPS methacrylate, the aggregate of the polar vinyl polymer and BiTEMPS methacrylate (and optional additives) totaling 100 wt % of the crosslinked composition. The crosslinked composition has

[0045] (i) a storage modulus value E' greater than 1 MPa at 60°C;

[0046] (ii) a storage modulus value E' at 140°C greater than 0.1 MPa;

[0047] (iii) a tan delta value of less than 0.17 at 60°C; and

[0048] (iv) a tan δ value of less than 0.62 at 140°C.

[0049] D. Blend Components

[0050] In one embodiment, the crosslinkable composition and / or the crosslinked composition comprises a blend component. Non-limiting examples of suitable blend components include ethylene vinyl acetate (EVA), polyolefins (e.g., polyethylene other than polar vinyl 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; polybutene (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 such as polyvinyl chloride, polystyrene, polyurethane, etc.; and mixtures thereof.

[0051] In one embodiment, the polyolefin is a homopolymer such as polyethylene, polypropylene, polybutene, polypentene-1, poly-3-methylbutene-1, poly-4-methylpentene-1, polyisoprene, polybutadiene, poly-1,5-hexadiene, polyhexene-1, polyoctene-1, and polydecene-1.

[0052] Non-limiting examples of polyethylenes suitable as blend components (other than polar ethylene polymers crosslinked with BITEMPS methacrylate) 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 polypropylenes 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 combinations thereof.

[0053] E. Additives

[0054] The crosslinkable composition and / or crosslinked composition may contain one or more optional additives. Non-limiting examples of suitable additives include grafting initiators, crosslinking catalysts, blowing agents, blowing agent activators (e.g., zinc oxide, zinc stearate, etc.), auxiliary 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 additives may be greater 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.

[0055] In one embodiment, the crosslinkable composition and / or the crosslinked composition comprises an antioxidant. Non-limiting examples of suitable antioxidants include aromatic amines or hindered amines, such as alkyl diphenylamines, phenyl-α-naphthylamines, alkyl or aralkyl substituted phenyl-α-naphthylamines, alkylated p-phenylenediamines, tetramethyl diamino diphenylamine, etc.; phenols such as 2,6-di-tert-butyl-4-methylphenol; 1,3,5-trimethyl-2,4,6-tris (3',5,-di-tert-butyl-4-hydroxybenzyl) benzene; tetrakis [(methylene (3,5-di-tert-butyl-4-hydroxyhydrocinnamate)] methane (e.g., IRGANOX TM 1010, available from Ciba Geigy, New York); acryloyl-modified phenol; octadecyl 3,5-di-tert-butyl-4-hydroxycinnamate (e.g., IRGANOX TM 1076, commercially available from Ciba Geigy); phosphites and phosphonites; hydroxylamines; benzofuranone derivatives; and combinations thereof. When used, the amount of antioxidant in the composition can be from greater than 0% to 5% by weight, or from 0.0001% to 2.5% by weight, or from 0.001% to 1% by weight, or from 0.001% to 0.5% by weight of the total weight of the composition.

[0056] In one embodiment, the crosslinkable composition and / or the crosslinked composition comprises a UV stabilizer. Non-limiting examples of suitable UV stabilizers include benzophenones, benzotriazoles, aryl esters, oxanilides, acrylates, formamidines, carbon black, hindered amines, nickel quenchers, hindered amines, phenolic antioxidants, metal salts, zinc compounds, and combinations thereof. When used, the amount of the UV stabilizer may be greater than 0% to 5% by weight, or 0.01% to 3% by weight, or 0.1% to 2% by weight, or 0.1% to 1% by weight of the total weight of the composition.

[0057] In one embodiment, the crosslinkable composition and / or the crosslinked composition include a colorant or pigment. The non-limiting example of suitable colorants or pigments includes inorganic pigments, for example, metal oxides such as iron oxide, zinc oxide and titanium dioxide, mixed metal oxides, carbon black, organic pigments such as anthraquinone, anthraquinone, azo and monoazo compounds, arylamide, benzimidazolone, BONA lake, diketopyrrolopyrrole, dioxazine, disazo compounds, diarylide compounds, flavanone, indanthrone, isoindolinone, isoindolinone, metal complex, monoazo salt, naphthol, b-naphthol, naphthol AS, naphthol lake, perylene, perylone, phthalocyanine, pyranthrone, quinacridone and quinophthalone, and combinations thereof. When used, the amount of colorant or pigment in the composition can be greater than 0% by weight to 10% by weight, or 0.1% by weight to 5% by weight, or 0.25% by weight to 2% by weight of the total weight of the composition.

[0058] In one embodiment, the crosslinkable composition and / or the crosslinked composition comprises 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, aluminum oxide, hydrated aluminum oxide such as aluminum oxide trihydrate, glass microspheres, ceramic microspheres, thermoplastic microspheres, barite, wood flour, glass fiber, carbon fiber, marble powder, cement powder, magnesium oxide, magnesium hydroxide, antimony oxide, zinc oxide, barium sulfate, titanium dioxide, titanates, and combinations thereof.

[0059] In one embodiment, the filler is barium sulfate, talc, calcium carbonate, silicon dioxide, glass, glass fiber, aluminum oxide, titanium dioxide or a mixture thereof. In another embodiment, the filler is talc, calcium carbonate, barium sulfate, glass fiber or a mixture thereof. When used, the amount of filler in the composition can be greater than 0% to 80% by weight, or 0.1% to 60% by weight, or 0.5% to 40% by weight, or 1% to 30% by weight, or 10% to 40% by weight of the total weight of the composition.

[0060] In one embodiment, the crosslinkable composition and / or the crosslinked composition comprises a lubricant. Non-limiting examples of suitable lubricants include fatty alcohols and dicarboxylic acid esters thereof, 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 may be greater than 0% to 5% by weight, or 0.1% to 4% by weight, or 0.1% to 3% by weight of the total weight of the composition.

[0061] In one embodiment, the crosslinkable composition and / or the crosslinked composition include 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., glyceryl monostearate), ethoxylated alkylamines, diethanolamine, 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 may be greater than 0% to 5% by weight, or 0.01% to 3% by weight, or 0.1% to 2% by weight of the total weight of the composition.

[0062] In one embodiment, the crosslinkable composition and / or the crosslinked composition include a blowing agent. "Blowing agent" is a substance that can produce a porous structure in the composition by 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 organic physical blowing agents, such as aliphatic hydrocarbons, such as propane, n-butane, isobutane, n-pentane, isopentane and n-hexane; alicyclic 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 dichloromethane; and dialkyl ethers, such as dimethyl ether, diethyl ether and methyl ethyl ether.

[0063] The limiting examples of suitable organic blowing agents include aliphatic hydrocarbons with 1-6 carbon atoms, aliphatic alcohols with 1-3 carbon atoms, and fully and partially halogenated aliphatic hydrocarbons with 1-4 carbon atoms. The limiting examples of suitable aliphatic hydrocarbons include methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, etc. The limiting examples of suitable aliphatic alcohols include methanol, ethanol, n-propyl alcohol, and isopropyl alcohol. The limiting examples of suitable fully and partially halogenated aliphatic hydrocarbons include fluorocarbons, chlorocarbons, and chlorofluoro compounds. Non-limiting examples of suitable fluorocarbons include methyl fluoride, perfluoromethane, ethyl fluoride, 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, and perfluorocyclobutane. Non-limiting examples of suitable partially halogenated chlorocarbons and chlorofluoro compounds 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 chlorofluoro compounds include trichloromonofluoromethane (OPOI 1), dichlorodifluoromethane (CFO-12), trichlorotrifluoroethane (CFO-113), 1,1,1-trifluoroethane, pentafluoroethane, dichlorotetrafluoroethane (CFO-114), chloroheptafluoropropane, and dichlorohexafluoropropane. Non-limiting examples of suitable chemical blowing agents include azodicarbonamide, azobisisobutyronitrile, benzenesulfonylhydrazide, 4,4-hydroxybenzenesulfonylsemicarbazide, p-toluenesulfonylsemicarbazide, barium azodicarboxylate, N,N'-dimethyl-N,N'-dinitrosoterephthalamide, and trihydrazinotriazine.

[0064] BiTEMPS methacrylate is a "dynamic crosslinker." The dynamic crosslinker BiTEMPS methacrylate enables the formation of a crosslinked network with a polar vinyl polymer through disulfide bonds between the chains of the polar vinyl polymer (in the presence of a free radical initiator), thereby forming a crosslinked polar vinyl polymer composition. The crosslinking is dynamic because the disulfide bonds can be broken when the crosslinked polar vinyl polymer composition is subjected to a "reprocessing temperature," thereby allowing chain movement and exchange, which 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. At the reprocessing temperature, the disulfide bonds in the crosslinked polar vinyl polymer composition are broken to form a reprocessable polar vinyl polymer composition. The reprocessable polar vinyl composition is cooled to below the reprocessing temperature to form a re-crosslinked polar vinyl polymer composition.

[0065] The dynamic crosslinker BiTEMPS methacrylate enables cyclic "reprocessing" to make new polymer articles. When the crosslinked polar ethylene polymer composition is heated to the reprocessing temperature, the disulfide bonds are broken or otherwise cleaved, allowing the previously crosslinked polar ethylene polymer composition to flow at the reprocessing temperature, thereby forming a "reprocessable polar ethylene polymer composition". Heating to the reprocessing temperature enables chain scission and polymer chain flow, thereby allowing the polar ethylene composition to be easily reshaped. At the reprocessing temperature, the reprocessable polar ethylene polymer composition is no longer crosslinked, but is flowable, allowing the now flowable, reprocessable polar ethylene polymer composition (with BiTEMPS methacrylate) to be formed and / or manufactured into a new preform or article. Upon cooling to below the "reprocessing temperature", the disulfide bonds are formed again, the network is reestablished, and the re-crosslinked polar ethylene composition is formed in a new article configuration, returning to high viscosity (no flow at room temperature) and resistance to mechanical deformation indicative of a crosslinked network. When the newly formed article of the reprocessable polar ethylene polymer composition is cooled to below the reprocessing temperature, the disulfide bonds in the reprocessable polar ethylene polymer composition are reestablished and the polar ethylene polymer (with BiTEMPS methacrylate) becomes a recrosslinked polar ethylene polymer composition in the shape of the newly manufactured article. Below the reprocessing temperature, the network disulfide bonds are stable and the recrosslinked polar ethylene polymer composition exhibits high viscosity and resistance to mechanical deformation indicative of the crosslinked network. This cycle of crosslinking / reprocessing / recrosslinking and manufacturing into new articles can be repeated.

[0066] Without being bound by a particular theory, the number of "reprocessing" cycles possible for the crosslinked polar ethylene polymer compositions of the present invention (before competing thermal and oxidative permanent crosslinking occurs and prevents further reprocessing) can be determined by calculating the ratio of the melt viscosities of the crosslinked polar ethylene polymer composition before and after a reprocessing cycle. For the reprocessable, crosslinked polar ethylene polymer composition, 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.

[0067] Other metrics used to monitor the number of "reprocessing" cycles possible for the BiTEMPS methacrylate dynamic crosslinker before competitive oxidative permanent crosslinking occurs include visual observation. The mechanically deformed formed film is heated to the reprocessing temperature and visually inspected to determine if the mechanically deformed film has healed to form a stable film. This measure of reprocessability is recorded in Table 2 below.

[0068] The present disclosure provides a method. In one embodiment, the method comprises:

[0069] The first article is heated to a reprocessing temperature. The first article is composed of a cross-linked polar ethylene polymer composition, the cross-linked polar ethylene polymer composition comprising (i) an ethylene polymer; and (ii) 2,2,6,6-tetramethyl-4-piperidinyl methacrylate disulfide (BiTEMPS methacrylate). The method includes forming the first article into a reprocessable polar ethylene polymer composition at a reprocessing temperature. The method includes forming the reprocessable polar ethylene composition into a reprocessed preform at a reprocessing temperature. The method includes cooling the reprocessed preform to below the reprocessing temperature and forming a second article composed of a re-cross-linked polar ethylene polymer composition, the re-cross-linked polar ethylene polymer composition consisting of (i) a polar ethylene polymer and (ii) BiTEMPS methacrylate, the second article being different from the first article.

[0070] In one embodiment, the forming step is a procedure selected from the group consisting of injection molding, extrusion molding, thermoforming, blow molding, overmolding, insert molding, blow molding, casting, tentering, and combinations thereof.

[0071] Non-limiting examples of suitable articles (first article and second article) for the cross-linked / re-cross-linked polar ethylene polymer (with BiTEMPS methacrylate) composition of the present invention include elastic films; elastic fibers; soft-touch items such as toothbrush handles and appliance handles; pads and profiles; adhesives (including hot melt adhesives and pressure sensitive adhesives); footwear (including soles and shoe insoles); 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; pipes; weather strips; lid linings; flooring; and combinations thereof.

[0072] By way of example and not limitation, some embodiments of the present disclosure will now be described in detail in the following examples.

[0073] 1. Materials

[0074] The materials used in the comparative samples (CS) and the inventive examples (IE) are provided in Table 1 below.

[0075] Table 1

[0076]

[0077] 1. Synthesis of BiTEMPS Methacrylate

[0078] To synthesize BiTEMPS methacrylate, 2,2,6,6-tetramethyl-4-piperidinyl methacrylate disulfide (8.78 g, 39.0 mmol, provided by TCI America) was first dissolved in anhydrous petroleum ether (about 90 mL, provided by Sigma-Aldrich, dried over molecular sieves for 48 hours before use) and cooled to -70 °C in a dry ice / acetone bath. Afterwards, sulfur monochloride (1.30 g, 9.7 mmol, provided by Sigma-Aldrich) was dissolved in anhydrous petroleum ether (about 1.25 mL) and added dropwise to the reaction vessel over a 30-minute period. The solution was stirred at -70 °C for another 30 minutes and at room temperature for 15 minutes. Next, BiTEMPS methacrylate was precipitated by pouring the reaction solution into a large amount of distilled water and stirring at room temperature overnight. The precipitate was collected, vacuum filtered, and vacuum dried at 60 °C for 48 hours to obtain BiTEMPS methacrylate as shown in the following structure 1.

[0079]

[0080] 2. Preparation of cross-linked composition

[0081] Appropriate masses of starting materials (including polymer pellets (polar vinyl polymer), crosslinker (BiTEMPS methacrylate) and free radical initiator (DCP)) were weighed separately on an analytical balance (usually 2 g polymer, 0.1 g crosslinker and 0.02 g free radical initiator). Prior to synthesis, the cup of a Dynisco (formerly Atlas) laboratory mixing molder (LMM) was charged with the target polymer, heated to above its melt transition temperature, and mixed for 3-5 minutes to rinse out impurities. After removing polymer debris from the rinse, the weighed polymer pellets and the powder mixture of the crosslinker and free radical initiator were added to the cup with a spatula. The starting materials were added in a certain amount so that they were evenly distributed throughout the cup before mixing. In addition, three steel balls (diameter ~5 mm) were evenly added to the cup to simulate the extrusion process during molten state mixing. Next, the temperature of the LMM was raised to above the melting transition temperature of the polymer, and the starting material was mixed at this temperature at 120 rpm (maximum rotation speed) for 3 minutes to 5 minutes to ensure homogenization of the components in the molten state while minimizing free radical initiation. For polymer 1, the mixing temperature was 100°C. After this homogenization, the temperature of the LMM was raised to 160°C to start the free radical initiation and crosslinker grafting process. Mix at this temperature for about 20 minutes. During mixing, the rotor of the LMM was manually cycled up and down regularly to promote homogenization of the blend. After mixing for 20 minutes, mixing was stopped and the crosslinked polymer blend was removed from the cup by a spatula.

[0082] The cross-linked composition (network blend) was cut into pieces and compression molded in a PHI press (model 0230C-X1) at 160°C and 8MPa for 30 minutes to form a film having a size of 50 mm long, 25 mm wide and 0.65 mm thick to obtain a first molded sample. The film was cut into millimeter-sized pieces and compression molded under the same conditions to obtain a second molded sample, and this procedure was repeated again to obtain a third molded sample. Strips were cut from each sample film for dynamic mechanical analysis (DMA).

[0083] 3. Polymer 1

[0084] Table 2 is provided below.

[0085]

[0086] Table 2 shows E' and tan δ at 60°C and 140°C for IE1 crosslinked compositions (network formulations) of Polymer 1. At 60°C, the E' values ​​of the network polymers are equal (of the same order of magnitude) to the E' values ​​of the corresponding virgin polymers within experimental uncertainty. Dynamic crosslinking and changes in crystallinity after processing may result in slightly reduced (reduced crystallinity reduces E' to below the melt transition temperature despite enhanced crosslinking) or slightly increased (crystallinity is slightly affected and crosslinking enhances E') values ​​at this temperature compared to the virgin polymer. At this temperature, sequential moldings of IE1 crosslinked compositions containing Polymer 1 exhibited E' values ​​that were approximately equal (of the same order of magnitude) to the E' values ​​of the corresponding virgin polymer and the first molded sample within experimental uncertainty.

[0087] At 140°C, the E' value of the IE1 crosslinked composition (network polymer) is greater than the E' value of the corresponding virgin polymer 1 because virgin polymer 1 does not have the network characteristics that produce large E' values ​​(>0.1 MPa) above the melt transition temperature. At 140°C, successive moldings of the IE1 crosslinked polymer composition exhibit E' values ​​that are approximately equal (same order of magnitude) or slightly greater (due to additional crosslinks formed during processing) than the E' value of the first molded sample within the experimental uncertainty.

[0088] The IE1 crosslinked compositions (network formulations) exhibited lower tan delta values ​​at both 60°C and 140°C than their virgin counterparts, polymer 1, due to the presence of greater crosslinking in the network material. Furthermore, these values ​​were maintained in samples molded continuously at both 60°C and 140°C. The IE1 crosslinked compositions shown in Table 2 demonstrate that polymer 1 not only exhibits a significant dynamic network response after crosslinking (>1 MPa at 60°C and >0.1 MPa at 140°C), but is also reprocessable and able to recover its E' and tan delta values ​​after consecutive compression molding cycles. Comparative samples that were processable failed to achieve a significant network response, while those that did produce a significant network response could not be reprocessed and were unable to recover thermomechanical properties after processing due to the presence of permanent crosslinks rather than sufficient dynamic crosslinks.

[0089] Table 2 provides the thermal properties (melting range and crystallinity) of the virgin polymer 1 (comparative sample) and the crosslinked composition of Example IE1 of the present invention (network formulation) as determined by DSC. Reactive crosslinking reduces the order of the formed crystalline structure during cooling after processing, slightly reduces the crystallinity, and reduces the melting peak and endpoint of the network polymer compared to the virgin counterpart polymer 1 (comparative sample).

[0090] It is particularly intended that the present disclosure is not limited to the embodiments and descriptions contained herein, but includes modifications of those embodiments including parts of the embodiments and combinations of elements of different embodiments as appear within the scope of the following claims.

Claims

1. A crosslinkable polymer composition, comprising: Polar vinyl polymers; free radical initiators; and 2,2,6,6-Tetramethyl-4-piperidinyl methacrylate disulfide (BiTEMPS methacrylate). 2 . The crosslinkable polymer composition according to claim 1 , wherein the polar ethylenic polymer has a melt index of 0.1 g / 10 min to 100 g / 10 min.

3. The crosslinkable polymer composition according to any one of claims 1 to 2, wherein the polar ethylene-based polymer is selected from the group consisting of ethylene / carboxylic acid copolymers, ethylene / acrylic acid copolymers (EAA), ethylene / vinyl acetate copolymers (EVA), ethylene / ethyl acrylate copolymers (EEA), ethylene / butyl acrylate copolymers (EBA), ethylene / methyl methacrylate copolymers, ethylene / butyl methacrylate copolymers, ethylene / octadecyl acrylate copolymers, ethylene / octadecyl methacrylate copolymers, ethylene / octyl acrylate copolymers, ethylene / 2-ethylhexyl acrylate copolymers, ethylene / dodecyl acrylate copolymers, 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. The crosslinkable polymer composition according to any one of claims 1 to 4, comprising: 70 wt % to 98.5 wt % of the polar ethylene polymer; 0.5 wt % to 10.0 wt % of a free radical initiator; and 1 wt % to 20 wt % BiTEMPS methacrylate.

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

7. A cross-linked composition, comprising: Polar vinyl polymers; and 2,2,6,6-Tetramethyl-4-piperidinyl methacrylate disulfide (BiTEMPS methacrylate).

8. The cross-linked composition according to claim 7, wherein the cross-linked composition comprises a bond of structure 2 Structure 2 9. The cross-linked composition according to any one of claims 7 to 8, comprising: 80 to 99 weight percent of a polar ethylene polymer having a melt index of 0.1 to 100 g / 10 min; and 20 wt % to 1 wt % of said 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 ethylene / carboxylic acid copolymers, ethylene / acrylic acid copolymers (EAA), ethylene / vinyl acetate copolymers (EVA), ethylene / ethyl acrylate copolymers (EEA), ethylene / butyl acrylate copolymers (EBA), ethylene / methyl methacrylate copolymers, ethylene / butyl methacrylate copolymers, ethylene / octadecyl acrylate copolymers, ethylene / octadecyl methacrylate copolymers, ethylene / octyl acrylate copolymers, ethylene / 2-ethylhexyl acrylate copolymers, ethylene / dodecyl acrylate copolymers, polyvinyl chloride (PVC), and combinations thereof.

11. The cross-linked composition according to any one of claims 7 to 10, wherein The polar vinyl polymer is a native polar vinyl polymer prior to crosslinking of the crosslinking composition; and The cross-linked composition has (i) a storage modulus value E' at 140°C, which is greater than the storage modulus value E' of the native polar ethylene polymer at 140°C; (ii) a tan δ value at 60°C that is less than the tan δ value at 60°C of the native polar ethylene polymer; and (iii) a tan δ value at 140°C that is less than the tan δ value at 140°C of the native polar ethylene polymer.

12. The cross-linked composition according to any one of claims 7 to 11, comprising: 3 wt % to 20 wt % BiTEMPS methacrylate; and The cross-linked composition has (i) a storage modulus value E' greater than 1 MPa at 60°C; (ii) a storage modulus value E' greater than 0.1 MPa at 140°C; (iii) a tan delta value of less than 0.17 at 60°C; and (iv) a tan δ value of less than 0.62 at 140°C.

13. A method comprising: heating a first article to a reprocessing temperature, wherein the first article is composed of a crosslinked polar ethylene polymer composition, the crosslinked polar ethylene polymer composition comprising (i) a polar ethylene polymer; and (ii) 2,2,6,6-tetramethyl-4-piperidinyl methacrylate disulfide (BiTEMPS methacrylate); forming the first article into a reprocessable polar ethylene polymer composition at the reprocessing temperature; forming the reprocessable polar ethylene composition into a reprocessable preform at the reprocessing temperature; as well as The reprocessed preform is cooled to below the reprocessing temperature and forms a second article composed of a re-crosslinked polar ethylene polymer composition, wherein the re-crosslinked polar ethylene polymer composition is composed of (i) the polar ethylene polymer and (ii) the BiTEMPS methacrylate, and the second article is different from the first article.

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