Recycled polymer compositions and methods thereof

Abstract

The present invention provides a method comprising treating a crosslinked polymer and a catalyst to form a type of vitrifier during a melt processing operation, the crosslinked polymer comprising at least one monomer selected from vinyl esters, C2-C12 olefins, and combinations thereof. The method may include mixing a crosslinked polymer, a catalyst, and an uncrosslinked polymer at a temperature higher than the processing temperature of the uncrosslinked polymer to form a polymer composition, wherein each of the crosslinked polymer and the uncrosslinked polymer comprises at least one monomer selected from vinyl esters, C2-C12 olefins, and combinations thereof, and wherein the amount of the crosslinked polymer present is at least 15% by weight relative to the total amount of the crosslinked polymer and the uncrosslinked polymer combined.

Description

Technical Field

[0001] Invention Field

[0002] This invention relates to a recycled polymer composition and a method thereof. Prior Technology

[0003] Background of the Invention

[0004] Ethylene vinyl acetate (EVA) is widely used in the manufacture of foams due to its light weight and very high toughness, resilience, and compression set. EVA foams have found applications in demanding fields, such as running shoe midsoles and automotive and construction applications, including internal fillers, carpet padding, and gaskets. The polymer structure required for EVA shoe midsoles and other foam applications is a three-dimensional network formed by cross-linked adjacent polymer molecules.

[0005] Dynamically cross-linked polymer networks offer a balance of performance, properties, and durability. However, the same characteristics that make permanent networks excellent candidates for high-performance foams present significant environmental challenges. Once formed, these network structures do not melt, flow, or dissolve, thus limiting their applicability to conventional reprocessing or recycling methods.

[0006] Industrial waste generated during the processing of permanent crosslinked polymers cannot be fully reintroduced into the manufacturing process as secondary feedstock, and only a small portion of industrial waste from crosslinked polymers is ground and reintroduced as filler. Similarly, end-of-life components generated from permanently crosslinked polymers have limited recycling options, such as energy-intensive grinding operations that produce only low-value materials. As a result, a significant proportion of industrial waste and end-of-life components accumulate as environmental waste.

[0007] Besides the obvious environmental impact, the fact that covalently cross-linked EVA foam cannot be melted and reprocessed represents a huge cost for manufacturers. The high volume of waste limits the use of primary materials and incurs waste disposal costs.

[0008] There is a need for technologies that enable the reprocessing of cross-linked polymers, especially cross-linked foamed EVA. Summary of the Invention

[0009] Invention Summary

[0010] This summary is provided to introduce the selection of concepts further described in the following detailed description. This summary is not intended to identify as a key or essential feature of the claimed subject matter, nor is it intended to be used as an aid to limit the scope of the claimed subject matter.

[0011] In one embodiment, the specific example disclosed herein relates to a method comprising treating a crosslinked polymer with a catalyst to form a dynamically crosslinked polymer during a melt processing operation, the crosslinked polymer comprising at least one monomer selected from vinyl esters, C2-C12 olefins, and combinations thereof.

[0012] In another embodiment, a specific example disclosed herein relates to a method comprising mixing a crosslinked polymer, a catalyst, and an uncrosslinked polymer at a temperature above the processing temperature of the uncrosslinked polymer to form a polymer composition, wherein each of the crosslinked polymer and the uncrosslinked polymer comprises at least one monomer selected from vinyl esters, C2-C12 olefins, and combinations thereof, and wherein the amount of the crosslinked polymer present is at least 15 by weight relative to the total amount of the crosslinked polymer and the uncrosslinked polymer combined.

[0013] In another instance, a specific example disclosed herein relates to a thermoplastic polymer composition which is generated by treating a crosslinked polymer with a catalyst to form a dynamically crosslinked polymer during a melt processing operation, the crosslinked polymer comprising at least one monomer selected from vinyl esters, C2-C12 olefins and combinations thereof.

[0014] In another instance, a specific example disclosed herein relates to a thermoplastic polymer composition produced by mixing a crosslinked polymer, a catalyst, and an uncrosslinked polymer at a temperature higher than the processing temperature of the uncrosslinked polymer to form a polymer composition, wherein each of the crosslinked polymer and the uncrosslinked polymer comprises at least one monomer selected from vinyl esters, C2-C12 olefins, and combinations thereof, and wherein the amount of the crosslinked polymer present is at least 15 by weight relative to the total amount of the crosslinked polymer and the uncrosslinked polymer combined.

[0015] In another instance, the specific example disclosed herein relates to an article comprising a thermoplastic polymer composition, wherein the composition is generated by treating a crosslinked polymer with a catalyst to form a dynamically crosslinked polymer during a melt processing operation, the crosslinked polymer comprising at least one monomer selected from vinyl esters, C2-C12 olefins and combinations thereof.

[0016] In another embodiment, a specific example disclosed herein relates to an article comprising a thermoplastic polymer composition, wherein the composition is formed by mixing a crosslinked polymer, a catalyst, and an uncrosslinked polymer at a temperature higher than the processing temperature of the uncrosslinked polymer to form a polymer composition, wherein each of the crosslinked polymer and the uncrosslinked polymer comprises at least one monomer selected from vinyl esters, C2-C12 olefins, and combinations thereof, and wherein the amount of the crosslinked polymer present is at least 15 by weight relative to the total amount of the crosslinked polymer and the uncrosslinked polymer combined.

[0017] In another instance, the specific example disclosed herein relates to a method for manufacturing a printed article comprising successive printed layers of a polymer composition, wherein the composition is generated from processing a crosslinked polymer and a catalyst to form a dynamically crosslinked polymer during a melt processing operation, the crosslinked polymer comprising at least one monomer selected from vinyl esters, C2-C12 olefins and combinations thereof.

[0018] In another embodiment, the specific example disclosed herein relates to a method for manufacturing a printed article comprising successive printed layers of a polymer composition, wherein the composition is formed by mixing a crosslinked polymer, a catalyst, and an uncrosslinked polymer at a temperature higher than the processing temperature of the uncrosslinked polymer to form a polymer composition, wherein each of the crosslinked polymer and the uncrosslinked polymer comprises at least one monomer selected from vinyl esters, C2-C12 olefins, and combinations thereof, and wherein the amount of the crosslinked polymer present is at least 15 by weight relative to the total amount of the crosslinked polymer and the uncrosslinked polymer combined.

[0019] In another embodiment, a specific example disclosed herein relates to a method for reprocessing a polymer composition comprising reprocessing a polymer composition derived from a treated crosslinked polymer and a catalyst to form a dynamically crosslinked polymer during a melt processing operation, the crosslinked polymer comprising at least one monomer selected from vinyl esters, C2-C12 olefins, and combinations thereof. The reprocessing is performed above the melting or softening temperature of the thermoplastic polymer, wherein after the reprocessing, the polymer composition retains at least 40% of its initial storage modulus plateau region above its melting temperature, as measured by dynamic mechanical analysis, compared to the polymer composition before the reprocessing.

[0020] In another embodiment, a specific example disclosed herein relates to a method for reprocessing a polymer composition comprising reprocessing a polymer composition formed from a mixture of a crosslinked polymer, a catalyst, and an uncrosslinked polymer at a temperature above the processing temperature of the uncrosslinked polymer, wherein each of the crosslinked polymer and the uncrosslinked polymer comprises at least one monomer selected from vinyl esters, C2-C12 olefins, and combinations thereof, and wherein the amount of the crosslinked polymer present is at least 15% by weight relative to the total amount of the crosslinked polymer and the uncrosslinked polymer. The reprocessing is performed above the melting or softening temperature of the thermoplastic polymer, wherein after the reprocessing, the polymer composition retains at least 40% of its initial storage modulus plateau region above its melting temperature, as measured by dynamic mechanical analysis, compared with the polymer composition before the reprocessing.

[0021] Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims. Simple Explanation of the Diagram

[0022] Figure 1-3 shows the DMA test results.

[0023] Figures 4-5 show the thermal reactions of multiple samples after reactive extrusion.

[0024] Figure 6-9 shows the viscoelastic response at 170 °C.

[0025] Figures 10A-12B show the stress relaxation results for multiple samples. Figures 10A, 11A, and 12A illustrate the magnitude of this stress relaxation behavior, and Figures 10B, 11A, and 12B show the normalized stress relaxation. The horizontal line in the normalized curve indicates where the normalized modulus reaches the value of 1 / e.

[0026] Figure 13-15 shows the results of reprocessing multiple samples. Implementation

[0027] Detailed Description of Preferred Embodiments

[0028] The specific examples disclosed herein relate to a polymer composition and a method for forming the polymer composition. The polymer composition can be formed in the presence of a catalyst by reprocessing a cross-linked polymer to form a dynamically cross-linked polymer. In particular, the reprocessed cross-linked polymer may include polymers formed from olefins, vinyl esters, or combinations thereof. Specific examples may also include an uncross-linked polymer bonded to the cross-linked polymer and the catalyst, thus resulting in a polymer composition that can have a multiphase structure.

[0029] Dynamically cross-linked polymers refer to dynamically cross-linked systems, also known as "ionic or covalent adaptive networks." These are a type of chemically cross-linked polymer where external stimuli (temperature, stress, pH, etc.) trigger bond exchange reactions, allowing changes in the network topology while maintaining a fixed number of bonds and crosslinks. The dynamic bonds present in dynamically cross-linked polymers can undergo association exchange reactions, thus altering the network topology. Even though the total number of bonds remains constant over time and temperature, the material will release stress and flow. Dynamically cross-linked polymers exhibit the characteristics of cross-linked materials at ambient temperatures (high chemical resistance, excellent mechanical properties), while at high temperatures they can be treated or reprocessed like thermoplastics.

[0030] According to one or more specific examples, cross-linked polymers that may otherwise be unprocessable can be mixed or processed with a catalyst and a selectively uncross-linked polymer. For example, this mixing or processing can occur in an extruder to convert the cross-linked polymer into a dynamically cross-linked polymer, thus transforming the permanent covalent cross-linking in the cross-linked polymer into an adaptive network. Advantageously, the specific examples disclosed herein allow for the incorporation of increased waste or recycled cross-linked material into the polymer composition, thereby reducing the amount of waste. Furthermore, it is envisioned that polymer compositions incorporating highly cross-linked polymers can still possess desired properties, such as elongation at break, tensile stress at break, flexural modulus, and / or cantilever beam impact resistance, for specific applications. In one or more specific examples, the polymer composition (when cross-linked) can possess one or more of these properties, which are at least equal to or greater than those of the individual cross-linked polymer. However, it is also envisioned that for some applications, properties lower than those of the individual cross-linked polymer are acceptable (or even desired). Furthermore, objects formed from this polymer composition can possess fracture stress, elongation, hardness, compression set, impact strength, density, tear strength, springback, abrasion resistance, etc., all of which are equivalent to those formed from an uncrosslinked polymer without dynamic crosslinking. In other words, the inclusion of this dynamically crosslinked polymer within the uncrosslinked polymer matrix does not negatively impact the object's properties.

[0031] Cross-linked polymers

[0032] As discussed, specific examples of this disclosure may allow for the addition of previously crosslinked polymers.

[0033] In one or more specific examples, the crosslinked polymer comprises at least one monomer selected from the following: C2-C12 olefins, such as ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, etc.; vinyl esters, such as vinyl acetate, vinyl propionate, vinyl laurate, vinyl esters of neodecanoic acid, etc.; and combinations thereof. Thus, for example, it is contemplated that the crosslinked polymer may include polymers such as polyethylene, including high-density polyethylene, low-density polyethylene, linear low-density polyethylene, very low-density polyethylene; polypropylene; ethylene and / or propylene copolymers, such as ethylene / propylene copolymers, ethylene vinyl acetate, ethylene propylene diene monomer (EPDM), ethylene / styrene copolymers, ethylene / acrylate copolymers, and poly(vinyl acetate). In copolymers of olefins and vinyl esters, it is contemplated that the vinyl ester may act as a comonomer in any amount ranging from a lower limit of 1, 5, 10, 15, 18, or 20% to an upper limit of 25, 40, 60, or 80%. In one or more particularly specific instances, vinyl acetate may be used as a monomer or comonomer.

[0034] It is also envisioned that the crosslinked polymer may include branched vinyl ester comonomers (combined alone with ethylene to form copolymers, or combined with ethylene and vinyl acetate to form terpolymers). Such copolymers and terpolymers are described in U.S. Patent Application No. 17 / 063,488, the entire contents of which are incorporated herein by reference. For example, the branched vinyl ester monomer may include monomers having a general structure (I): (I) R4 and R5 have a combined number of 6 or 7 carbon atoms. However, it is also contemplated that vinyl esters of other branches described in U.S. Patent Application No. 17 / 063,488 may be used.

[0035] When referring to a cross-linked polymer formed from a polymer composition described herein, it is intended that the polymer is already cross-linked (including permanent covalent bonds) before the addition of a catalyst, so that after treatment in the presence of the catalyst, the permanent cross-linking of the cross-linked polymer is transformed into a dynamically cross-linked system, i.e., a dynamically cross-linked polymer.

[0036] In one or more specific instances, the crosslinked polymer has been previously treated, indicating that it has undergone one or more prior treatment steps that resulted in the formation of the covalent crosslinks before being mixed / treated with the catalyst, such as, but not limited to, crosslinking in a pressure cooker, hot air tunnel, UV radiation, foaming, melt processing, injection molding, or compression molding. Furthermore, it is also contemplated that in one or more specific instances, the crosslinked polymer may have been previously compounded with one or more additives or fillers; while in other specific instances, it may be a crosslinked polymer without such additional components. Therefore, in one or more specific instances, the crosslinked polymer is a recycled resin, such as a post-consumer resin, a post-industrial resin, or other waste material that would otherwise be unusable for reprocessing due to the presence of covalent crosslinks. Generally, once this crosslinking is formed, these network structures no longer melt, flow, or dissolve, thus preventing the application of conventional reprocessing or recycling methods. For example, in one or more specific instances, the crosslinked polymer is derived from waste material from molded EVA midsole shoes or recyclable soles. Thus, for example, this previously treated crosslinked polymer may have been previously molded or extruded, and the subsequent runners, sprues, overflows, defective parts and the like may have been ground or shredded and combined with a catalyst to transform the crosslinked polymer into a dynamically crosslinked network.

[0037] It should also be understood that the cross-linked polymer may originate from other industrial manufacturing processes, such as waste materials or other sources that cannot be reused as recyclable items due to the presence of cross-linking. However, this specific example uses a new type of glass-like polymer to replace the permanent cross-linking, thereby creating a polymer network that can undergo topological recombination under certain environmental conditions, overcoming the technical obstacles related to the permanent nature of the covalent bonds that hold the cross-linked polymer network together.

[0038] In one or more specific instances, the crosslinked polymer, such as a waste polymer, forms at least 5% by weight, 10% by weight, 15% by weight, at least 20% by weight, at least 25% by weight, or at least 50% by weight of the polymer composition, wherein the polymer composition comprises a composition consisting of the crosslinked polymer, a catalyst, and one or more selective non-polymer additives, i.e., without uncrosslinked polymers.

[0039] catalyst

[0040] In one or more specific examples, the crosslinked polymer system is combined with a catalyst that facilitates the exchange reaction used for the dynamic crosslinking described above. In one or more specific examples, the catalyst is a metal salt selected from the group consisting of: metal salts, metal oxides, metal alkoxides, metal acrylates, metal acetylacetonates, metal hydrides, metal halides, and metal hydroxides. This metal may include alkali metals, alkaline earth metals, transition metals, and rare earth metals, such as zinc, tin, molybdenum, vanadium, copper, tungsten, magnesium, cobalt, calcium, titanium, potassium, lithium, sodium, nickel, aluminum, lead, iron, and zirconium.

[0041] In one or more specific examples, the catalyst is selected from borates, diamines, diols, dianic acids, dianhydrides, and combinations thereof. In one or more specific examples, these catalysts may be used in combination with the previously described metal salt catalysts.

[0042] In one or more specific instances, the amount of the catalyst present is more than 2 mol% relative to the crosslinked polymer system. It is conceivable that a catalyst sufficient to produce dynamic crosslinking within the crosslinked polymer and the uncrosslinked polymer and to form a bridge between the two can be added.

[0043] Uncrosslinked polymers

[0044] In one or more specific examples, the uncrosslinked polymer comprises at least one monomer selected from the following: C2-C12 olefins, such as ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, etc.; vinyl esters, such as vinyl acetate, vinyl propionate, vinyl laurate, vinyl esters of neodecanoic acid, etc.; and combinations thereof. Thus, for example, it is contemplated that the uncrosslinked polymer may include polymers such as polyethylene, including high-density polyethylene, low-density polyethylene, linear low-density polyethylene, very low-density polyethylene; polypropylene; ethylene and / or propylene copolymers, such as ethylene / propylene copolymers, ethylene vinyl acetate, ethylene propylene diene monomer (EPDM), ethylene / styrene copolymers, ethylene / acrylate copolymers, and poly(vinyl acetate). In copolymers of olefins and vinyl esters, it is contemplated that the vinyl ester may act as a comonomer in any amount ranging from a lower limit of 5, 10, 15, 18, or 20% to an upper limit of 25, 40, 60, or 80%. In one or more specific instances, vinyl acetate can be used as a monomer or comonomer. According to ASTM D1238, the ethylene vinyl acetate can have a melt flow range of 0.1 to 300 g / 10 min, measured at 2.16 kg at 190 °C.

[0045] It is also envisioned that the uncrosslinked polymer may include branched vinyl ester comonomers (combined alone with ethylene to form copolymers, or combined with ethylene and vinyl acetate to form terpolymers). Such copolymers and terpolymers are described in U.S. Patent Application No. 17 / 063,488, the entire contents of which are incorporated herein by reference. For example, the branched vinyl ester monomer may include monomers having a general structure (II): (I) R4 and R5 have a combined number of 7 carbons.

[0046] In one or more specific instances, the uncrosslinked polymer is formed in amounts less than 85% by weight, less than 80% by weight, less than 75% by weight, or less than 50% by weight of the polymer composition.

[0047] After combining the cross-linked polymer, the catalyst, and the uncross-linked polymer, the resulting polymer composition can be multiphase, having a matrix phase of the uncross-linked polymer and a dispersed phase of a dynamically cross-linked polymer therein. Furthermore, it is also envisioned that, depending on the mixing or processing conditions, the dynamically cross-linked polymer can be formed on the surface of the dispersed phase, in the matrix phase, and at the interface between the two phases.

[0048] Selective additives

[0049] In addition to crosslinked polymers, catalysts, and selectively uncrosslinked polymers, the polymer compositions disclosed herein may also include one or more selective additives, such as, but not limited to, fillers, foaming agents, foaming accelerators, curing agents, crosslinking agents, free radical initiators, elastomers, plasticizers, processing aids, mold release agents, lubricants, dyes, pigments, antioxidants, light stabilizers, flame retardants, or other additives that modify the balance of stiffness and elasticity in the polymer composition, such as fibers, fillers, and other reinforcing elements. In some specific examples, one or more of these additives may be added during the initial mixing or melt processing of the crosslinked polymer and the catalyst; and in one or more specific examples, one or more of these additives may be compounded in subsequent process steps.

[0050] Polymer compositions according to this disclosure may include one or more foaming accelerators (also known as kickers) that enhance or initialize the action of the foaming agent by lowering the relevant activation temperature. For example, the foaming accelerator may be used if the selected foaming agent reacts or decomposes at temperatures above 170 °C, such as 220 °C or higher, where the surrounding polymer will degrade upon heating to the activation temperature. The foaming accelerator may include any suitable foaming accelerator capable of activating the selected foaming agent. In one or more specific examples, suitable foaming accelerators may include cadmium salts, cadmium-zinc salts, lead salts, lead-zinc salts, barium salts, barium-zinc (Ba-Zn) salts, zinc oxide, titanium dioxide, triethanolamine, diphenylamine, sulfonated aromatic acids and their salts, and the like. Polymer compositions according to a particular specific example of this disclosure may include zinc oxide as one of the one or more foaming accelerators. In certain specific instances, the foaming accelerator may be included in the elastomer EVA composition in addition to or in place of the polymer composition itself.

[0051] The polymer composition disclosed herein may include one or more foaming agents to produce an expanded polymer composition and a foam. The foaming agent may be a solid, liquid, or gaseous foaming agent. In a specific example using a solid foaming agent, the foaming agent may be a powder or granules combined with a polymer composition.

[0052] The foaming agents disclosed herein may include chemical foaming agents that decompose at polymer processing temperatures, releasing foaming gases such as N₂, CO, CO₂, and similar gases. Examples of such chemical foaming agents may include organic foaming agents, including hydrazides such as toluenesulfonylhydrazine; hydrazides such as oxydiphenylsulfonylhydrazine, diphenyl-4,4'-disulfonic acid hydrazide, and similar compounds; nitrates; azo compounds such as azodimethylamine, cyanopentanoic acid, azobis(isobutyronitrile), and N-nitroso compounds, and other nitrogen-based materials; and other compounds known in the art.

[0053] The inorganic chemical foaming agent may include carbonates, such as sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, ammonium carbonate and the like, which may be used alone or in combination with weak organic acids such as citric acid, lactic acid or acetic acid.

[0054] The polymer composition disclosed herein may include one or more plasticizers to adjust the physical properties and processability of the composition. In certain specific examples, in addition to other plasticizers and polymer plasticizers, the plasticizers disclosed herein may include one or more of the following: bis(2-ethylhexyl) phthalate (DEHP), diisononyl phthalate (DINP), bis(n-butyl) phthalate (DNBP), butyl benzyl phthalate (BZP), diisodecyl phthalate (DIDP), di-n-octyl phthalate (DOP or DNOP), di-o-octyl phthalate (DIOP), diethyl phthalate (DEP), diisobutyl phthalate (… DIBP), di-n-hexyl phthalate, trimethyl triphenyltricarboxylate (TMTM), tri-(2-ethylhexyl) triphenyltricarboxylate (TEHTM-MG), tri-(n-octyl, n-decyl) triphenyltricarboxylate, tri-(heptyl, nonyl) triphenyltricarboxylate, n-octyl triphenyltricarboxylate, bis(2-ethylhexyl) adipate (DEHA), dimethyl adipate (DMD), monomethyl adipate (MMAD), dioctyl adipate (DOA), dibutyl sebacate (DBS); polyesters of adipic acid, such as VIERNOL, dibutyl maleate (DBM), diisobutyl maleate (DIBM); benzoates, epoxidized soybean oil, n-ethyltoluenesulfonamide, n-(2-hydroxypropyl)benzenesulfonamide, n-(n-butyl)benzenesulfonamide, tricresyl phosphate (TCP), tributyl phosphate (TBP), glycol / polyester, triethylene glycol dihexanoate, 3gh), tetraethylene glycol diheptanoate, polybutene, acetylated monoglycerides; alkyl citrate, triethyl citrate (TEC), citric acid... Triethyl citrate, tributyl citrate, tributyl citrate, trioctyl citrate, trioctyl citrate, trihexyl citrate, trihexyl citrate, butyl trihexyl citrate, trihexyl o-butyl citrate, trimethyl citrate; alkyl sulfonate phenyl ester, diisononyl 2-cyclohexanedicarboxylate; nitroglycerin, glyceryl trinitrate, dinitrotoluene, trimethylolethane trinitrate, diethylene glycol dinitrate, triethylene glycol dinitrate, bis(2,2-dinitropropyl)formal, bis(2,2-dinitropropyl)acetal, 2,2,2-trinitroethyl 2-nitoxyethyl ether, mineral oil. In particular specific instances, one or more of these plasticizers may be mineral oil.

[0055] The polymer composition disclosed herein may include one or more inorganic fillers, such as talc, glass fiber, marble powder, cement powder, clay, carbon black, feldspar, silica or glass, fuming silica, silicates, calcium silicate, silica powder, glass microspheres, mica; metal oxide particles and nanoparticles, such as magnesium oxide, antimony oxide, zinc oxide; inorganic salt particles and nanoparticles, such as barium sulfate, silica ore, alumina, aluminum silicate, titanium dioxide, calcium carbonate, polyhedral oligomeric silsesquioxane (POSS), recycled EVA and other recycled rubber. As defined herein, the recycled EVA may be derived from refractory material that has undergone at least one processing method such as molding or extrusion, and from the subsequent grinding or shaving of the runner, gating system, overflow, defective parts and the like. Although, according to the specific examples disclosed herein, this recycled material is formed in combination with a catalyst into a polymer composition having a dynamically cross-linked network as described herein, it is also contemplated that additional recycled EVA or other polymers may be added as fillers in subsequent chemical steps.

[0056] deal with

[0057] In one or more specific examples, the crosslinked polymer, catalyst, and selectively uncrosslinked polymer are subjected to melt processing to form a dynamically crosslinked polymer and the claimed polymer composition. In particular, the crosslinked polymer, catalyst, and selectively uncrosslinked polymer can be mixed at high temperatures to reduce the viscosity of the crosslinked polymer and increase the rate of the dynamic crosslinking reaction. For example, the mixture of the crosslinked polymer, catalyst, and uncrosslinked polymer can be subjected to a processing temperature higher than that of the uncrosslinked polymer to form the polymer composition. That is, the mixture can be subjected to a temperature higher than the melting or softening point of the uncrosslinked polymer. This temperature should be selected according to the requirements of the chosen processing operation, as long as it does not exceed the degradation temperature of the polymer. The softening point of the amorphous uncrosslinked polymer is determined according to ASTM D-1525 by the Vicat method; and the melting point of the semi-crystalline uncrosslinked polymer is measured according to DSC.

[0058] In one or more specific examples, the polymer compositions according to this disclosure can be prepared by continuous or discontinuous extrusion or by continuous or batch mixing. The method can use single, twin, or multi-screw extruders, which in some specific examples can operate within a temperature range of 100 °C to 270 °C; and in some specific examples, 140 °C to 230 °C. In some specific examples, the raw materials (crosslinked polymer, catalyst, and uncrosslinked polymer) are added to the extruder, simultaneously or sequentially into the main or secondary feeder. Other specific examples can use kneaders, calenders, or other closed mixers.

[0059] A method for preparing a polymer composition according to the present disclosure may include the following general steps: combining a cross-linked polymer, a catalyst, and a selectively uncross-linked polymer in an extruder; melt-extruding the cross-linked polymer and the catalyst to form a dynamically cross-linked polymer; selectively dispersing the dynamically cross-linked polymer within an uncross-linked polymer; and forming pellets, threads, or powders of the polymer composition.

[0060] Advantageously, the process disclosed herein can be continuous, such that the crosslinked polymer and catalyst can be added to the process in a fixed and continuous manner (e.g., at the first end of the extruder), and the resulting polymer composition can be formed in a fixed and continuous manner at the end of the process (e.g., at the second end of the extruder). That is, adding additional crosslinked polymer and catalyst to the process (at the first end of the extruder) simultaneously generates the resulting polymer composition from the process (at the second end of the extruder).

[0061] In one or more specific instances, the cross-linked polymer, particularly derived from waste or molded parts, can be broken down into smaller particles. It is envisioned that, in one or more specific instances, this size reduction can occur during the extrusion of the cross-linked polymer and the catalyst. However, it is also envisioned that at least a portion of this size reduction can occur in a prior step of grinding, milling, or otherwise finely chopping larger waste flakes into particles, wherein these particles can be readily fed into an extruder and / or have sufficient surface area to react with the catalyst and dynamically cross-link during the extrusion process. For example, the cross-linked polymer, after size reduction and acceptance of dynamic cross-linking, can have a lower limit of any 1, 5, 10, 15, 20, 30, 40, 50, or 100 micrometers, and an upper limit of any 100, 500, 1000, 5000, 10000, or 100000 micrometers, wherein any lower limit can be used in combination with any upper limit.

[0062] In one or more specific instances, after dynamic crosslinking, the time dependence of the elastic storage modulus at temperatures above 90 °C is a shift relative to the pure composition. This time dependence of the composition can be determined as the time it takes for the standardized relaxation modulus to reach 1 / e relative to the initial value (G0, plateau modulus). The value of the standardized relaxation modulus can be obtained by an exponential decay fit to the elastic storage modulus data. This plateau modulus corresponds to the fit at t=0 seconds, and is also referred to as G0.

[0063] Considering dynamic crosslinking, specific examples disclosed herein also relate to the reprocessing of a crosslinked polymer composition. In one or more specific examples, due to the intrinsic properties of the chemicals used, the crosslinked polymer formulation can be reprocessed or recycled using a treatment similar to that applied to the virgin polymer during the initial crosslinking process. Waste or end-of-life components can still be used as secondary feedstock through regrinding or other necessary processes to feed the material with an acceptable reduction in processing performance or properties into the desired operation. Generally, this is intended so that the reprocessing parameters are similar to those used in the initial manufacturing process. Advantageously, the polymer composition can be reprocessed and its properties can be substantially maintained, as compared immediately before the reprocessing. In particular, in one or more specific examples, after the reprocessing, the polymer composition retains at least 40% of its initial storage modulus plateau region above its melting temperature, as measured by dynamic mechanical analysis, as compared to the polymer composition before the reprocessing.

[0064] It is also envisioned that the reprocessing will occur repeatedly (through multiple cycles). In one or more specific instances, after the repeated reprocessing, such as after 3 or even 5 reprocessing cycles, the polymer composition retains at least 40% of its initial storage modulus flat region above its melting temperature, as measured by dynamic mechanical analysis, such as when compared with the polymer composition before the reprocessing.

[0065] The polymer composition prepared by this method can be in particulate form and can be applied to various molding processes to produce finished products, including processes selected from the following: injection molding, foaming, compression molding, steam chest molding, supercritical molding, laminated manufacturing and similar processes.

[0066] In one or more specific instances, the polymer composition may be formulated in certain specific instances into extruded filaments or granules (or pellets) that can be used in a multilayer manufacturing process.

[0067] Typically, commercially available examples of additive manufacturing technologies include extrusion-based techniques such as fused filament fabrication (MJF), fused deposition modeling (FDM), or freeforming; and other techniques such as electrophotography (EP), inkjet printing, selective laser sintering (SLS), high-speed sintering (HSS), powder / binder inkjet printing (BJ), and vat photopolymerization. For each of these technologies, the initial digital representation of the 3D part is thinly slit into multiple horizontal layers. Then, a toolpath is generated for each slit layer, providing instructions for printing that supply layer to a particular additive manufacturing system. Specific additive manufacturing technologies particularly suitable for this polymer composition include, for example, fused filament fabrication and powder bed fusion (SLS, HSS, and BJ) technologies.

[0068] In filament fabrication, an extruder heats a plastic filament to produce a polymer melt, which is then extruded through a nozzle onto a printing substrate in a controlled pattern. The material is deposited to form a continuous layer. The filament can have a diameter of, for example, 1.0 to 4.0 mm, including filaments with a diameter range of, for example, 1.5 to 3 mm, such as, for example, 1.75 mm or 2.85 mm.

[0069] Powder bed fusion molding technology uses powdered material instead of liquid or molten resin in the build area. For example, in selective laser sintering (SLS), a laser is used to selectively sinter a layer of powder to sinter the material together. This process is then repeated layer by layer until the build is complete. When the object is fully formed, it is left in the machine to cool before being removed. In high-speed sintering (HSS), manufacturing is performed by depositing a fine polymer powder layer, after which an inkjet printhead deposits an infrared (IR) absorbing fluid (or toner powder) directly onto the surface of the powder to be sintered. The entire build area is then irradiated using an IR radiation source, such as an infrared lamp, causing the printhead to absorb this energy and melt and sinter the underlying powder. This process is then repeated layer by layer until the build is complete. While SLS and HSS are detailed as embodiments of powder bed melt molding technology, it is also contemplated that the polymer composition can be adapted for use in other powder bed melt molding technologies, such as selective thermal sintering (SHS), selective absorbing sintering (SAS), selective inhibition sintering (SIS), and adhesive spraying. In these powder bed melt molding technologies, the polymer composition can be provided as powder with an exemplary particle size distribution: d50 ranging from 30 to 90 micrometers, d90 up to 150 micrometers, and d10 at least 10 micrometers.

[0070] In one or more specific examples, the article is selected from the group consisting of: shoe midsoles, hot melt adhesives, gaskets, hoses, cables, wires, sealing systems, conveyor belts, foxing tape for shoe upper repair, NVH materials, sound insulation materials, roofing materials, and industrial flooring. In specific examples of multilayer articles, it is envisioned that at least one layer comprises the polymer composition disclosed herein.

[0071] As mentioned above, objects formed from this polymer composition can possess fracture stress and elongation, hardness, compression set, impact strength, density, tear strength, springback, abrasion resistance, etc., which are equivalent to those formed from an uncrosslinked polymer without any dynamically crosslinked polymer within it. In other words, the inclusion of this dynamically crosslinked polymer within the matrix of the uncrosslinked polymer does not negatively impact the properties of the object.

[0072] For a specific example of an expanded object, the expanded object may have a density range of 0.2 to 0.6 g / cm³ according to ASTM D792, such as 0.45 g / cm³ or lower, 0.43 g / cm³ or lower, 0.42 g / cm³ or lower, 0.41 g / cm³ or lower, 0.40 g / cm³ or lower, 0.38 g / cm³ or lower, 0.35 g / cm³ or lower, 0.32 g / cm³ or lower, or 0.30 g / cm³ or lower.

[0073] The expanded object according to one or more specific examples of this disclosure may have an Asker C hardness, as determined by JIS K7312, ranging from any of the lower limit of 15, 20, 25, 30 or 35 to the upper limit of 40, 45, 50, 55 or 60, wherein any lower limit may be paired with any upper limit.

[0074] An expanded object according to one or more specific examples of this disclosure may have a springback coefficient of at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, or at least 70%, as determined by ASTM D2632.

[0075] The expansion object according to one or more specific examples of this disclosure may have an abrasion coefficient of 150 cubic millimeters or less, 140 cubic millimeters or less, 130 cubic millimeters or less, 120 cubic millimeters or less, 110 cubic millimeters or less, 100 cubic millimeters or less, 75 cubic millimeters or less, or 50 cubic millimeters or less, as measured by ISO 4649:2017 with a 5 Newton load.

[0076] The expanded object according to one or more specific examples disclosed herein may have a shrinkage coefficient of 3% or less, 2.8% or less, 2.5% or less, 2.3% or less, or 2.0% or less, as determined using the PFI method (PFI "Testing and Research Institute for the Shoe Manufacturing Industry" in Pirmesens-Germany) at 70 °C for 1 hour.

[0077] The expanded object according to one or more specific examples of this disclosure may have a compression set of less than 15%, less than 12%, less than 10%, or less than 8%, as determined by ASTM D395, Method B, at 23°C and 25% strain for 22 hours.

[0078] The expanded object according to one or more specific examples of this disclosure may have a compression set of less than 50%, less than 45%, less than 40%, or less than 35%, as determined by ASTM D395, Method B, at 50 °C and 50% strain for 6 hours.

[0079] The expanded object according to one or more specific examples of this disclosure may have a tear strength of at least 3 N / mm, at least 3.5 N / mm, at least 4 N / mm, at least 4.5 N / mm, or at least 5 N / mm, as determined by ASTM D624.

[0080] The expanded object according to one or more specific examples of this disclosure may have an adhesive strength of at least 2.5 N / mm², at least 3.0 N / mm², at least 3.5 N / mm², at least 4.0 N / mm², or at least 4.5 N / mm², as determined by ABNT-NBR 10456.

[0081] For a specific instance of a compacted object, one or more instances of the compacted object may have a Shore A hardness range of 60 to 70, a bursting strength greater than 7 MPa, a bursting elongation greater than 250%, and a compression set (NBR 10025, Method B, 22 hours, 70 °C) less than 35%, according to NBR 13756-1996.

[0082] In one or more specific instances, the polymer composition can be used to form a shoe midsole, and the polymer used to form the crosslinked polymer composition may be EVA waste, such as runners, sprues, overflows, defective parts, and the like from shoe midsole molding operations, which is then ground or shredded. The ground EVA waste can be combined with a catalyst and selectively virgin EVA in an extruder to form the polymer composition described herein. Therefore, the polymer composition can be used to form a shoe midsole.

[0083] Example

[0084] Test methods

[0085] Notched cantilever beam impact resistance

[0086] Notched cantilever impact tests were conducted according to ASTM D256, Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics, Method A, on a Ceast Resil 25 Digital Pendulum Unit, Model 6545. Unless otherwise specified, pendulum capacity: 2.0 Joules. Sample size: several sizes; notch depth: 0.1 inches; number of samples tested for each sample type: 5 (minimum); test temperature: samples were kept at room temperature (23 °C) during testing.

[0087] Bending Modulus

[0088] Three-point bending tests were conducted on an Instron 3366 unit with Bluehill Universal software, following the principles of ASTM D790, Procedure A - Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials. Strain ratio: see results below; crosshead speed: see results below; sample size: 0.125" thickness x 0.5" width x 5.0" length; carrier span: 2 inches; number of samples tested for each sample type: 5; three-point bending test results at each strain ratio: speed: 0.05 inches / minute, span: 2.0 inches.

[0089] Tensile properties

[0090] Tensile tests were performed on an Instron 3366 unit with Bluehill Universal software, applying principles from ASTM D638 Tensile Properties of Plastics. A 10 kN load cell was used. A long-stroke elongator was used to determine the strain values. Clamping rate: 2.0 inches / minute; Sample size: ASTM Type I dog bone; Intersample gauge length: 2.0 inches.

[0091] Dynamic mechanical analysis

[0092] Dynamic mechanical analysis was performed using Anton Parr MCR 501 with a single cantilever beam fixture.

[0093] Differential Scan Card Meter

[0094] To elucidate the formation of dynamic cross-linked networks, thermal reactions were measured using a Differential Scanning Card (DSC) Q200 instrument manufactured by TA Instruments.

[0095] DSC method:

[0096] In the first heating step, the sample is heated to 160 °C at a heating rate of 10 °C / min. The temperature is then held constant at 160 °C. The sample is then cooled to -20 °C at a rate of 10 °C / min and equilibrated at -20 °C for 1 minute. In the second heating step, the sample is heated to 160 °C at a heating rate of 10 °C / min, held at 160 °C for 1 minute, and then cooled to 30 °C at a rate of 10 °C / min.

[0097] Shear rheology

[0098] Shear rheological tests were conducted using the following method: first, a frequency scan, immediately followed by a time scan, and then a further frequency scan. Comparisons were made among samples after different thermal cycles and at different frequencies to understand the potential effect of the catalyst on the polymer composition. All tests were conducted at 170 °C in a nitrogen (N₂) atmosphere using a TA Instruments DHR3 dynamic shear oscillation rheometer, with parallel plates assisted, at a diameter of 25 mm and a spacing of 1 mm.

[0099] Test conditions: First frequency scan system from 628.32 to 0.75 radians / second, deformation within the linear viscoelastic region (LVR). Time scan system within this LVR at 1 radian / second for 60 minutes. Second frequency scan system within this LVR from 628.32 to 0.06 radians / second.

[0100] Stress relaxation

[0101] Stress relaxation measurements were obtained using an Ares G2 rheometer with a 25 mm parallel plate fixture. The spacing was set to 1.5 mm. The strain coefficient was set to 1% (within the linear range). An axial force of 5 Newtons was applied. Tests for each sample were conducted at four different temperatures (100 °C, 120 °C, 150 °C, and 170 °C).

[0102] The grinding of EVA waste and the melting / mixing of EVA with a dynamic crosslinking agent

[0103] The elastomer network is manufactured by reactive extrusion of ethylene-vinyl acetate copolymer (EVA) with ground EVA waste and zinc / carboxylate. Conventional EVA (Braskem commercial grade HM728, 28% VAc content, melt index (190 °C / 2.16 kg = 6 g / 10 min)) with ground peroxide-crosslinked EVA waste and zinc-core dicarboxylate is melted / mixed in a Theysohn TSK 21 mm twin-screw extruder. The extrusion conditions and mechanical properties are summarized in Tables 2 and 3.

[0104] Cross-linked EVA waste foam is obtained from commercial midsole manufacturers and ground into fine particles using an extruder operating at 190 °C.

[0105] Typical midsole components include: EVA polymer; inorganic salts, such as CaCO3 (1-5 wt%); foaming agents, such as azodimethylamine (2-3 wt%); and dicumyl peroxide curing agent (0.5-2 wt%). The particle size distribution of the milled waste was measured by laser diffraction using a Mastersizer instrument manufactured by Malvern. The average particle size is approximately 300 micrometers.

[0106] Examples 1 and 2 illustrate the effect of extruding EVA with ground EVA waste without the addition of a dynamic crosslinking agent. Examples 2 and 3 illustrate the effect of extruding a blend of zinc diacrylate with EVA and ground EVA waste. Examples 4 and 5 illustrate the effect of extruding a blend of zinc acetylacetonate with EVA and ground EVA waste. Table 1: Sample Preparations Base resin (weight %) Filler (weight %) Catalyst (by weight %) Sample number EVA HM728 EVA waste Zinc diacrylate Zinc acetylpyruvate Example 1 85 15 Example 2 70 30 Example 3 84 15 1.5 Example 4 67 30 3 Example 5 84 15 1.2 Example 6 68 30 2.4 Table 2: Extrusion Conditions Extruder temperature (°C) Sample number Area 1 Area 2 Area 3 Area 4 Area 5 mold Torque % Stud speed, rpm Example 1 158 159 159 157 154 150 54 266 Example 2 154 159 159 156 157 152 51 265 Example 3 154 159 159 156 157 153 56 266 Example 4 154 160 160 156 154 148 69 270 Example 5 157 159 161 156 155 150 56 268 Example 6 153 159 160 155 154 149 64 269

[0107] The resulting extrudate mixture was cooled in a water bath and collected as pellets. Small pellet samples were dried in a convection oven at 60 °C for at least 8 hours, and then molded into test specimen strips according to ASTM methods. Mechanical properties were measured using ASTM procedures, and the results are reported in Table 3.

[0108] The fact that the inventive composition can be readily processed using conventional (standard) injection molding methods for thermoplastic plastics demonstrates its melt processing capability. Table 3: Sample Characteristics Sample number Bending modulus, psi Cantilever beam impact resistance Tensile modulus, psi Peak tensile stress, psi Elongation at break, % Example 1 5087 1.5 1949 1490 327 Example 2 5977 1.6 2975 1174 202 Example 3 5302 1.5 1787 1884 413 Example 5 5123 1.5 1505 1791 408

[0109] Dynamic mechanical analysis

[0110] To elucidate the formation of the elastomer network after incorporation of EVA and Zn / carboxylate, dynamic mechanical analysis was performed on a molding plate (17.5 mm x 13.95 mm x 1.5 mm) using a single cantilever beam geometry. The samples were equilibrated at 150 °C for 5 minutes, and then the temperature was increased to 50 °C at a rate of 3.00 °C / min.

[0111] The storage modulus and tan Δ value were observed in the temperature range of 15-30 °C, as shown in Figures 1-3, which clearly demonstrate that the addition of zinc carboxylate to EVA increases the elastomer's reactivity. The modulus values ​​at 25 °C are reported in Table 4 below. Table 4: Modulus values ​​of samples at 25℃ Sample number Storage modulus, MPa Loss modulus, MPa Tan Δ HM 728 EVA (control) 28.7 2.1 0.07 Example 2 37.7 2.6 0.07 Example 4 40.7 3.0 0.07 Example 6 38.1 2.8 0.07

[0112] Differential Scan Card Meter

[0113] To further elucidate the formation of the elastomer network after incorporating EVA and Zn / carboxylate, DSC was used to measure the thermal reaction of the EVA waste blend after reactive extrusion. Figure 4 reports the melting curves after secondary melting following heating and cooling cycles. The melting peak of the blend including all EVA waste is similar to that of the EVA control sample. The presence of 30% waste results in a broader peak, but does not significantly shift the melting temperature of that peak.

[0114] The cooling curve of the sample, including the ground EVA waste, is shown in Figure 5. It has two distinct crystallization peaks, one at the same temperature as the EVA control and the other at a higher temperature, which can be attributed to the ground waste.

[0115] When zinc diacrylate or zinc acetylacetate is extruded with milled waste and EVA, the lower-temperature crystallization peak shifts to a significantly lower temperature. Unblended EVA HM728 has a Tc peak at approximately 54°C, and EVA blended with milled waste has a Tc peak at approximately 52°C. Samples extruded with Zn diacrylate or zinc acetylacetate have a Tc peak at approximately 43°C, a shift of almost 10°C. This shift suggests crosslinking of the EVA / waste blend containing Zn diacrylate or zinc acetylacetate after extrusion.

[0116] Shear rheology

[0117] Small-angle oscillating shear (SAOS) was used to measure the viscoelastic response at higher temperatures, as shown in Figures 6-9. Figure 7 shows that the sample containing Zn diacrylate has a significantly lower crossover frequency at 170 °C than the sample containing only waste material shown in Figure 6. The sample containing Zn diacrylate also has a significantly lower tan Δ peak than the sample containing only waste material, as shown in Figure 9. These observations demonstrate good elastomer behavior above the melting point of this EVA, indicating that a cross-linked network has been formed.

[0118] Stress / relaxation measurement

[0119] Stress relaxation measurements were performed to elucidate the dynamic cross-linking of the network system of the present invention, which can thus change its morphology in response to stimuli such as increased temperature.

[0120] The tested samples were the components of the invention described in Examples 2, 4 and 6 above.

[0121] The stress relaxation results are shown in Figures 10, 11, and 12, illustrating the time dependence of the storage modulus (G') at each test temperature. For each inventive material, G' = G'(t). For each EVA / waste composition, the G'(t) value decreases by at least 50% of G(t=0) within 10,000 seconds. The value of G(t=0) is obtained by fitting the data with an exponential decay. The relaxation modulus corresponds to the fit at t=0 seconds, which is also referred to as G0.

[0122] Reprocessing Experiment

[0123] To illustrate that the components of this invention can be reprocessed by heating and melting, the extruded pellets were pressurized multiple times in a Carver press using the conditions listed in the table below. The pellet samples were pressurized between steel plates using a 0.6 mm thick brass die to control sample thickness. After the first pressurization step, the membrane was cooled, cut into small pieces, and pressurized again to form a second membrane. The second membrane was cut into small pieces and pressurized to form a third membrane. After each pressurization, membrane samples were collected for dynamic mechanical analysis. First pressurization 5 minutes @ 110℃ 15 minutes @ 160℃, 20 bar The second and third pressurizations 5 minutes @ 110℃

[0124] The invention sample provides a smooth, uniform membrane after each pressurization, which illustrates the flow of the composition to obtain the shape of the mold.

[0125] The viscoelastic response of the pressurized membrane was measured using a rheometer equipped with a tensile clamp, manufactured by TA Instruments, via dynamic mechanical analysis (DMA) temperature scanning. The sample dimensions were 0.6 mm thick, 7 mm wide, and 22–26 mm long. The strain amplitude was 15 μm, the frequency was 1 Hz, and the heating rate was 3 °C per minute.

[0126] The elastic modulus and storage modulus values ​​are reported as a function of temperature. As shown in Figures 13-15, the composition of the invention has a flat storage modulus in the temperature range of about 20 °C to about 80 °C. After three processing steps, the flat storage modulus of the composition of the invention retains at least half of its initial value, wherein the initial value is the E' value after the first pressurization.

[0127] Although only a few specific examples of embodiments have been described in detail above, those skilled in the art will readily recognize that there are many possible modifications in these specific examples that do not substantially depart from the invention. Furthermore, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, the intended function plus means clause covers the structures described herein as performing the stated function, and is not only structural equivalents but also equivalent structures. Thus, while nails and screws may not be structural equivalents, where nails use a cylindrical surface to secure wooden parts together, screws use a helical surface, and in the context of fastening wooden parts, nails and screws may be equivalent structures. Except for those claims that explicitly use the term "means for" with the associated function, the applicant's express intention is not to invoke any limitation of 35 USC § 112(f) regarding any of the claims herein.

[0128] (none)

Claims

1. A method for forming a dynamically crosslinked polymer, comprising: treating a crosslinked polymer with a bond exchange and dynamic crosslinking promoting catalyst to form the dynamically crosslinked polymer during a melt processing operation, the crosslinked polymer comprising at least one monomer selected from vinyl esters, C2-C12 olefins, and combinations thereof.

2. A method for forming a polymer composition, comprising: mixing a crosslinked polymer, a bond exchange and dynamic crosslinking promoting catalyst, and an uncrosslinked polymer at a temperature above the processing temperature of an uncrosslinked polymer to form the polymer composition; wherein each of the crosslinked polymer and the uncrosslinked polymer comprises at least one monomer selected from vinyl esters, C2-C12 olefins, and combinations thereof; and wherein the amount of the crosslinked polymer present is at least 15 by weight relative to the total amount of the crosslinked polymer and the uncrosslinked polymer combined.

3. The method of claim 2, wherein the crosslinked polymer is previously treated, and / or wherein the uncrosslinked polymer is the original polymer.

4. The method of claim 2, wherein the polymer composition comprises a base phase of the uncrosslinked polymer and a dispersed phase of the dynamically crosslinked polymer.

5. The method of claim 2, wherein the crosslinked polymer is an ethylene vinyl acetate copolymer.

6. The method of claim 5, wherein the ethylene vinyl acetate has: a melt flow rate ranging from 0.1 to 300 g / 10 min, measured at 2.16 kg at 190 °C according to ASTM D1238; and / or a vinyl acetate content ranging from 5 to 80% by weight; and / or a particle size ranging from 1 to 100,000 micrometers.

7. The method of claim 2, wherein the uncrosslinked polymer is an ethylene vinyl acetate copolymer.

8. The method of claim 2, wherein the uncrosslinked polymer is a terpolymer of ethylene, vinyl acetate and branched vinyl esters.

9. The method of claim 2, wherein the catalyst is a metal salt selected from the group consisting of: metal salts, metal oxides, metal alkoxides, metal acrylates, metal acetylacetonates, metal hydrides, metal halides and metal hydroxides.

10. The method of claim 2, wherein the catalyst is selected from borates, diamines, diols, dianhydrides, dianhydrides, and combinations thereof.

11. The method of claim 2 further comprises: grinding the crosslinked polymer prior to mixing; and / or adding at least one additive selected from the group consisting of: fillers, fibers, elastomers, plasticizers, processing aids, mold release agents, lubricants, dyes, pigments, antioxidants, light stabilizers and flame retardants to the polymer composition.

12. The method of claim 2 further comprises: combining the polymer composition with a foaming agent, an accelerator and a curing agent; expanding the polymer composition; and / or molding the polymer composition.

13. The method of claim 2 further comprises extruding the polymer composition into fine lines having a diameter ranging from 1.5 to 3 millimeters; or into pellets.

14. A thermoplastic polymer composition manufactured by the method of claim 2.

15. An article comprising a thermoplastic composition, wherein the thermoplastic composition is the thermoplastic composition of claim 14.

16. The item as requested in item 15, wherein: The object is selected from the group consisting of: shoe midsoles, hot melt adhesives, gaskets, hoses, cables, wires, sealing systems, conveyor belts, leather for shoe upper repair, NVH materials, sound insulation materials, roofing materials, and industrial flooring; and / or the object has a density ranging from 0.1 to 0.4 g / cm³; and / or the object has a fracture stress and elongation, hardness, compression set, impact strength, density, tear strength, springback, and abrasion resistance equivalent to a reference object formed from an uncrosslinked polymer without dynamic crosslinking; and / or, according to NBR 13756-1996, the object has a hardness in the Shore A range of 60 to 70, a breaking strength greater than 7 MPa, an elongation at break greater than 250%, and a compression set (NBR 10025, Method B, 22 hours, 70 °C) less than 35%.

17. A method of manufacturing a printed article, comprising: sequentially printing layers of a polymer composition as claimed in claim 14.

18. The method of claim 17, wherein the sequential printing comprises: depositing a powder layer comprising the polymer composition on a target surface; and melting and sintering the polymer composition.

19. The method of claim 17, wherein the successive printing comprises: successively depositing layers of a molten polymer phase comprising the polymer composition.

20. A printed object formed by the method of claim 17.

21. A method of reprocessing a polymer composition, comprising: reprocessing the thermoplastic polymer composition at a temperature above the melting or softening temperature of the thermoplastic polymer composition as claimed in claim 14, wherein after the reprocessing, the polymer composition retains at least 40% of its initial storage modulus flat region above its melting temperature, as measured by dynamic mechanical analysis, compared with the polymer composition before the reprocessing.

Images