Highly conductive compounds containing HDPE and carbon nanotubes for battery electrode plates

Abstract

The thermoplastic composition comprises a polymer resin comprising about 35% to about 70% by weight, wherein the polymer resin comprises at least two polymer resins, at least one of which comprises a high-density polyethylene (HDPE) polymer having a crystallinity of at least 47% as measured by differential scanning calorimetry (DSC); about 10% to about 40% by weight of synthetic graphite; about 5% to about 15% by weight of carbon nanotubes (CNTs); and about 3% to about 15% by weight of conductive carbon black powder.

Description

[Technical Field]

[0001] This disclosure relates to thermoplastic compositions comprising high-density polyethylene and several forms of carbon fillers having good volume resistivity and mechanical properties. [Background technology]

[0002] The zinc-bromine battery was conceived in the late 1800s—see, for example, U.S. Patent No. 312,812 (granted to Bradley in 1885). The development of commercial zinc-bromine batteries has been hampered by: (1) the tendency of zinc to form dendrites after deposition, which can short-circuit the battery; and (2) the high solubility of bromine in aqueous zinc bromide electrolyte, which allows for diffusion and direct reaction with the zinc electrode, leading to the self-discharge of the battery. Controlling the pH of the electrolyte is crucial to reduce the zinc corrosion rate and mossy zinc deposits. These issues are discussed in “Zinc / Bromine Batteries,” Paul C. Butler et al., Report No. SAND2000-0893, pp. 37-1, 3, 6 (2000).

[0003] The search for carbon-plastic electrode composites to be used as electrode plates in zinc bromide batteries began in the late 1970s. U.S. Patent No. 4,169,816 ('816 Patent) by Exxon Research & Engineering describes, for example, a homogeneous blend of crystalline polypropylene-ethylene copolymer, conductive carbon black, a small amount of silica, and a fiber reinforcement selected from carbon fibers and mixtures of carbon and glass fibers. The composition was reported to have excellent strength, good extrudeability, excellent volume resistivity (1 Ohm.cm), and good impermeability. This patent indicates that, in order to impart conductivity, the composition should contain at least 15 parts by weight (pph) of finely divided conductive carbon powder per 100 parts (pph) of the copolymer. It also states that conductive carbon at 35 pph should not be used, otherwise the composition would be too brittle and not so easily extruded into thin, non-porous sheets. Furthermore, increasing the amount of carbon to about 35 pph tends to increase the permeability of thin sheets produced from such compositions to liquids such as bromine, for example. The finely divided conductive carbon black, such as that manufactured under the trade name Ketjen Black EC, is approximately 500m 2 It is preferable that the surface area exceeds / g.

[0004] Johnson Controls began researching plastic-carbon electrodes in the 1990s and reported that polypropylene-ethylene copolymer-based electrodes, developed by Exxon at the time, were susceptible to oxidative attack, swelling, and strain. They explained that the mechanism behind bromide attack was the vulnerability of tertiary hydrogens in the propylene chain backbone. To circumvent this problem, Johnson Controls selected high-density polyethylene (HDPE) homopolymer, which eliminates most, if not all, of the tertiary hydrogens on the backbone chain. Johnson Controls reported positive results in maturation tests with base polymer substitution, showing that HDPE outperformed EP copolymers.

[0005] Globe-Union Inc. (a subsidiary of Johnson Controls) obtained a patent in December 1992 for HDPE-based carbon-plastic electrodes. U.S. Patent No. 5,173,362 ('362 Patent) describes compositions for electrode systems, particularly compositions for use in bipolar electrodes in zinc-bromine batteries. These compositions preferably include carbon black as a conductive filler in the polymer matrix, along with reinforcing materials such as glass fibers. The strain of zinc-bromine electrodes experienced in the prior art and thought to be caused by physical expansion of the electrode due to bromine absorption by the electrode material is substantially eliminated in the compositions and manufacturing processes described in this patent. In this patent, the material is prepared using a lamination process known as glass-mat reinforced thermoplastic technology, or, in different embodiments, the substrate is prepared using a slurry process. Bromination, unlike chlorination, is highly selective to the chemistry of the polymer matrix used, as tertiary hydrogen in polypropylene systems reacts with bromine about 20,000 times faster than secondary hydrogen in polyethylene. Three types of carbon black were used in the described compositions, but Ketjenblack EC-300J grade provided the best combination of conductivity and processability / extrusion properties in terms of the amount of carbon used.

[0006] The '362 patent broadly describes carbon black and fiber loading ranges of 5–40% by weight and 10–70% by weight, respectively. However, since the exemplified compositions (Table 5) describe an 18% by weight carbon loading (identical to the Exxon '816 patent), the carbon and fiber loading used in the '362 patent is considered to be similar to that described in the '816 patent.

[0007] International (PCT) Publication WO2022 / 195511, filed by SHPP Global Technologies, describes a highly conductive thermoplastic composition, particularly a polyethylene-based composition containing graphite filler and carbon black powder, suitable for use in battery electrode applications. The described material has good chemical resistance and conductivity.

[0008] Another SHPP application, International Application No. PCT / IB2023 / 054050, describes highly filled plastic materials used for replacing metals in electrode plates of flow and non-flow batteries that operate at relatively high temperatures. These materials comprise at least one polyphenylene sulfide (PPS) and a mixture of synthetic graphite, carbon nanotubes, and conductive carbon black in different ratios.

[0009] Although formulations containing different carbon sources are described in the prior art, none have exhibited the required balance of electrical conductivity, chemical resistance, and processability (extrudability) for manufacturing thin sheets for battery electrode plates using conventional extrusion or molding processes.

[0010] These and other disadvantages are addressed by aspects of the present disclosure. Summary of the Invention

[0011] Aspects of the present disclosure relate to a thermoplastic composition comprising: from about 35 wt% to about 70 wt% of a polymer resin, wherein the polymer resin comprises at least two polymer resins, and at least one of the polymer resins comprises a high-density polyethylene (HDPE) polymer having a crystallinity of at least 47% as measured by differential scanning calorimetry (DSC); from about 10 wt% to about 40 wt% of synthetic graphite; from about 5 wt% to about 15 wt% of carbon nanotubes (CNT); and from about 3 wt% to about 15 wt% of conductive carbon black powder, wherein the combined weight percent values of all components do not exceed 100 wt%, and all weight percent values are based on the total weight of the composition. Brief Description of the Drawings

[0012] In the drawings, which are not necessarily drawn to scale, like numerals may describe like components in different figures. Like numerals with different letter suffixes may represent different instances of like components. The drawings generally illustrate various aspects discussed in this document by way of example and not by way of limitation.

[0013] [Figure 1] It is a graph showing elastic modulus properties for comparative and example compositions according to aspects of the present disclosure. [Figure 2] It is a graph showing tensile stress at break properties for comparative and example compositions according to aspects of the present disclosure. [Figure 3] It is a graph showing flexural modulus properties for comparative and example compositions according to aspects of the present disclosure. [Figure 4] It is a graph showing flexural stress at break properties for comparative and example compositions according to aspects of the present disclosure. [Figure 5] It is a graph showing melt viscosity properties for comparative and example compositions according to aspects of the present disclosure. [Figure 6] It is a graph showing specific gravity properties for comparative and example compositions according to aspects of the present disclosure. [Figure 7] It is a graph showing volume electrical resistivity properties for comparative and example compositions according to aspects of the present disclosure. DETAILED DESCRIPTION OF EMBODIMENTS

[0014] This disclosure relates to high-filler plastic materials used to replace metal electrode plates in flow and no-flow batteries, such as zinc bromide and vanadium redox batteries. These materials comprise at least one high-density polyethylene and a mixture of synthetic graphite, carbon nanotubes, and conductive carbon black in different ratios. Desired properties for these compounds may include conductivity, chemical resistance, and extrusion into thin plastic sheets using conventional polymer processing methods. Another potential use of these formulations is the replacement of metal and metallized polymer materials in EMI shielding of coaxial cables, mobile phones, computers, laptops, monitors, and other highly sensitive electronic devices requiring isolation from external electromagnetic fields.

[0015] Prior to the disclosure and description of these compounds, compositions, articles, systems, devices, and / or methods, it should be understood that, unless otherwise specified, they may vary in nature, and are not limited to specific synthesis methods or specific reagents. It should also be understood that the terms used herein are intended solely to describe specific embodiments and are not intended to limit them.

[0016] Various combinations of elements of this disclosure, such as combinations of elements from dependent claims that depend on the same independent claim, are encompassed by this disclosure.

[0017] Furthermore, unless otherwise specified, it should be understood that none of the methods described herein are ever intended to be construed as requiring their steps to be performed in a particular order. Therefore, if a claim for a method does not actually enumerate the order in which its steps should be followed, or if it is not specifically stated in the claims or description that the steps are limited to a particular order, then no order is ever intended to be inferred. This applies to any possible implicit grounds for interpretation, including logical issues relating to the arrangement of steps or operational flows, obvious meanings arising from grammatical structure or punctuation, and the number or type of embodiments described herein.

[0018] All publications referenced herein are incorporated herein by reference to disclose and describe methods and / or materials in connection with the citation of such publications.

[0019] definition It should be understood that the terms used herein are intended solely to describe and not to limit to specific embodiments. Where used herein and in the claims, the term “comprising” may include embodiments that “consist of” and “consisting essentially of.” Unless otherwise defined, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which this disclosure belongs. Several terms defined herein will be referenced herein and in the subsequent claims.

[0020] As used herein and in the appended claims, the singular forms "a," "an," and "the" refer to multiple subjects unless the context specifically indicates otherwise. For example, a reference to "polymer resin" includes mixtures of two or more polymer resins.

[0021] As used herein, the term “combination” includes blends, mixtures, alloys, reaction products, and the like.

[0022] A range can be expressed herein as from one value (the first value) to another value (the second value). When such a range is expressed, the range, in some aspects, includes one or both of the first and second values. Similarly, when a value is expressed as an approximation, the use of the antecedent "about" will be understood to mean that a particular value forms another aspect. It will be further understood that each endpoint of a range is important together with and independently of the other endpoints. There are several values ​​disclosed herein, and each value is also disclosed herein in addition to the value itself as "about" that particular value. For example, if the value "10" is disclosed, "about 10" is also disclosed. Each unit between two particular units is also disclosed. For example, if 10 and 15 are disclosed, 11, 12, 13, and 14 are also disclosed.

[0023] Where used herein, the terms “about” and “at or about” mean that the quantity or value in question may be the specified value, approximately the specified value, or nearly the specified value. Where used herein, it is generally understood that it is a nominal value with a variation of ±10%, unless otherwise specifically indicated or inferred. The terms are intended to convey that similar values ​​will promote equivalent results or effects enumerated in the claims. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics may be approximate and / or greater or less, as necessary, to reflect tolerances, conversion factors, rounding, measurement errors, and other factors known to the parties, although they are not and do not need to be. In general, quantities, sizes, formulations, parameters, or other quantities or characteristics are “about” or “approximate,” whether or not they are explicitly stated as such. Where “about” is used before a quantitative value, it is understood that the parameter also includes the specific quantitative value itself, unless otherwise specifically stated.

[0024] The components used to prepare the compositions of this disclosure, as well as the compositions themselves used in the methods disclosed herein, are disclosed. When these and other materials are disclosed herein, and when combinations, subsets, interactions, groups, etc., of these materials are disclosed, specific references to various individual and collective combinations and permutations of each of these compounds cannot be expressly disclosed, but it is understood that each is specifically contemplated and described herein. For example, when a particular compound is disclosed and discussed, and several modifications that can be made to several molecules containing the compound are discussed, all possible combinations and permutations of the compound and possible modifications are specifically contemplated unless otherwise indicated. Thus, when classes A, B, and C are disclosed as well as classes D, E, and F, and examples of combined molecules, it means that A-D are disclosed, and even if each is not individually listed, each is considered to be individually and collectively contemplated, and combinations A-E, A-F, B-D, B-E, B-F, C-D, C-E, and C-F are disclosed. Similarly, any subsets or combinations thereof are also disclosed. Therefore, for example, subgroups A-E, B-F, and C-E would be considered disclosed. This concept applies to all aspects of this application, including but not limited to steps in methods for preparing and using the compositions of this disclosure. Thus, where various additional steps that may be implemented exist, each of these additional steps may be implemented in any specific aspect or combination of aspects of the methods of this disclosure.

[0025] References in the specification and concluding claims to parts by weight of a particular element or component in a composition or article indicate the weight relationship between the element or component and any other element or component in the composition or article in which the parts by weight are represented. Thus, in a compound containing 2 parts by weight of component X and 5 parts by weight of component Y, X and Y exist in a weight ratio of 2:5, and such a ratio exists regardless of whether additional components are contained in the compound.

[0026] Unless otherwise stated, the weight percentage of an ingredient is based on the total weight of the formulation or composition containing the ingredient.

[0027] As used herein, the terms "number average molecular weight" or "M n " are used interchangeably and refer to the statistical average molecular weight of all polymer chains in a sample, defined by the formula: [[Formula]] defined by wherein M i is the molecular weight of the chain, N i is the number of chains of that molecular weight. M n can be determined for a polymer, such as a polycarbonate polymer, by methods well known to those skilled in the art, using molecular weight standards, for example polycarbonate standards or polystyrene standards, preferably certified or traceable molecular weight standards.

[0028] As used herein, the terms "weight average molecular weight" or "M w " are used interchangeably, defined by the formula: [[Formula]] defined by wherein M i is the molecular weight of the chain, N i is the number of chains of that molecular weight. Compared to M n M w takes into account the molecular weight of a given chain when determining the contribution to the molecular weight average. Therefore, the larger the molecular weight of a given chain, the more the chain contributes to M w M w can be determined for a polymer, such as a polycarbonate polymer, by methods well known to those skilled in the art, using molecular weight standards, for example polycarbonate standards or polystyrene standards, preferably certified or traceable molecular weight standards.

[0029] As used herein, the terms “polydispersion index” or “PDI” are interchangeable and are expressed in the formula:

number

[0030] The terms “residue” and “structural unit” as used in relation to the components of polymers are synonymous throughout this specification.

[0031] As used herein, the terms “weight percentage,” “weight% (wt%),” and “weight% (wt.%)” are interchangeable and, unless otherwise specified, indicate the weight percentage of a given component based on the total weight of the composition. That is, unless otherwise specified, all weight percentage values ​​are based on the total weight of the composition. It should be understood that the sum of the weight percentage values ​​for all components in the disclosed composition or formulation is equal to 100.

[0032] Unless otherwise stated herein, all test standards are the most current standards in effect at the time of filing this application.

[0033] Each of the raw materials used in the examples and / or comparative compositions described herein is either commercially available or / or the method for producing them is known to those skilled in the art.

[0034] It is understood that the compositions disclosed herein have a particular function. Certain structural requirements for performing the disclosed function are disclosed herein, and it is understood that there are various structures that can perform the same function related to the disclosed structure, and these structures will typically achieve the same result.

[0035] This disclosure describes highly filled plastic materials comprising at least one high-density polyethylene and a mixture of synthetic graphite, carbon nanotubes, and conductive carbon black in different ratios. The use of carbon nanotubes in these compositions allows for a reduction in graphite and carbon black loading, thus producing a material with similar conductivity but improved flow compared to compositions containing only graphite and carbon powder. Three desirable properties of these compounds include conductivity, chemical resistance, and processability / extrusion into thin plastic sheets using conventional polymer processing methods. One of the polymers used in the compositions of the present invention is 0.949 g / cm³ 3 The polymer was Formolene® HL5010, an ultra-high molecular weight ethylene-hexene copolymer with a crystallinity of approximately 61.5% when tested by DSC, and measured its density (ASTM D1505), chemical resistance (ESCR) (ASTM D1693) in 100% Igepal for at least 600 hours, melt flow rate (MFR) (ASTM D1238) at 10 g / 10 min at 190°C and 21.60 kg. This polymer exhibited excellent chemical resistance, for example, when tested at 60°C in a zinc bromide-based electrolyte solution used in redox non-flow batteries. Synthetic high-purity graphite, carbon nanotubes, and highly conductive carbon black powder are used as fillers to impart conductivity to the formulations of this disclosure. These HDPE-CNT-graphite-carbon compositions can be injection molded into plaques to produce samples for ASTM testing.

[0036] In some embodiments, the crystallinity of polymers such as HDPE is measured by DSC, and the enthalpy of melting (ΔH) is measured. 測定 )(△H meas) can be calculated by dividing by the enthalpy of melting for 100% crystallinity. Because there is limited information available regarding polymers with 100% crystallinity, the enthalpy of melting for 100% crystallinity is calculated rather than measured using indirect methods such as extrapolation of the Flory equation. The theoretical enthalpy of melting for 100% crystalline polyethylene can be used to calculate the crystallinity values ​​for the polymers described herein. 文献 (△H lit The value is known to be 293 joules per gram (J / g). In the case of polymer composites, as with the compositions of this disclosure, the equation for the crystallinity percentage may also include the weight fraction of fillers in the composite (since heat is used only to melt the polymer fraction in the formulation, not the fillers). Thus, the values ​​for “crystallinity” as used herein relate to the heat / enthalpy required to melt the polymer fraction of the sample compared to the heat that would be required if the polymer were 100% crystalline, and the percentage value is obtained by multiplying this enthalpy ratio by 100. Polymer density and crystallinity are not independent parameters but are related through a linear correlation. Exemplary calculations for the crystallinity of polyethylene polymers described herein are provided in Table 1 below. [Table 1]

[0037] The choice of polymer matrix affects the chemical resistance of the composition to the electrolyte solution used in non-flow redox batteries, and experiments have shown that low-density polyethylene generally exhibits a poor response to the environmental conditions encountered by electrode plate materials inside batteries. Copolymers of high-density polyethylene and hexene with at least 45% crystallinity have been found to exhibit excellent resistance to zinc bromide at the battery's operating temperature. The graphite used in the exemplary composition, TIMREX® KS44, is a high-purity, highly crystalline material produced at ultra-high temperatures by evaporating impurities such as metal oxides, sulfur, iron, and aluminum, resulting in pure carbon-synthetic graphite with over 99% purity across different particle sizes. A suitable carbon black for use in the compositions of this disclosure is Ketjenblack EC-300J, which has a dominant / base particle size of approximately 40 nm, with aggregates of several hundred nanometers in size and aggregates of 100-200 microns in size. The BET surface area of ​​this carbon black is approximately 800 m². 2 The unit is / gr (grams per square meter) (ASTM D3037), and the oil absorption rate (OAN) is approximately 365 ml / 100g (milliliters per 100 grams) when tested according to ASTM D2414.

[0038] To strike a balance between conductivity and processability / extrudeability in the molten material, it is desirable to select carbon black powder within a specific range of particle sizes. Carbon powder with small particle sizes (large surface area) is, for example, conductive but difficult to process, while carbon powder with large particle sizes (small surface area) is easily processable / extrudeable but typically exhibits low conductivity.

[0039] Suitable carbon nanotubes (CNTs) for use in the embodiments of this disclosure include, but are not limited to, PLASTICYL® HDPE1501CNTs from Nanocyl. The CNTs impart conductivity to the described compositions and are supplied in the form of custom-made HDPE-based masterbatches containing 15 wt percent NC7000 multi-walled carbon nanotubes. Typical loading for electrostatic dissipation applications is about 2% to 3% of carbon nanotubes in the final compound. Conductivity for a given loading depends primarily on the compounding conditions, the viscosity of the base resin, and the dilution equipment. NANOCYL® nanotubes are thin, multi-walled carbon structures produced by a catalytic chemical vapor deposition (CCVD) process. The carbon structures are tubular materials composed of carbon atoms with nanometer-sized diameters. The graphite layer can be visualized to some extent as a continuous, unbroken hexagonal mesh and a coiled chicken wire with carbon atoms at the vertices of the hexagons. Under the action of van der Waals forces, the carbon nanotubes tend to cluster into bundles or aggregates. As a result, carbon nanotubes appear as a black powder. However, at the nanoscale, they have a spaghetti-like structure. These nanotubes have an average diameter of about 10 nm (nanometers), a length of 1.5 microns, and a length of 250-300 m. 2 / gr surface area, and 10 -4 It has a volume resistivity of Ohm.cm.

[0040] The main advantage of carbon nanotubes is their less impact on the mechanical properties of compositions compared to other conductive fillers such as carbon black and graphite. This is because their high aspect ratios result in a relatively low amount of nanotubes required to achieve a particular conductivity. While CNT-based compositions typically have a higher viscosity than carbon black-based compositions with the same load, compositions containing CNTs may be easier to process because a lower amount of CNTs is required for the same conductive effect. The main advantages of using carbon nanotubes include, but are not limited to, high conductivity, good melt processability / extrusion, retention of important mechanical properties, good recyclability, and heat dissipation.

[0041] In some applications, the amount of carbon nanotubes present in the masterbatch may not be sufficient to achieve the extremely low electrical resistivity required by the application. In these cases, the effect provided by the nanotubes is complemented by the addition of different proportions of graphite and carbon black powder combinations. These CNT / graphite / carbon powder ratios are selected to maintain an optimal balance between conductivity and flow / processability / extrudeability. Certain amounts of graphite filler may be included in the formulations used to fabricate the electrode plates of batteries, as graphite is more chemically stable against halide attack than other forms of carbon, such as in zinc bromide redox flow and no-flow batteries, for the batteries to function properly. To reduce the cost of the final product, it would be desirable to reduce the CNT content used in the formulations. The HDPE-MWCNT masterbatch used in the materials of this disclosure may be diluted with a fixed amount of fresh, unfilled Formolene® HL5010 high-density polyethylene. The amount of masterbatch used in the compositions of this disclosure may vary from 45 to 100% by weight, and the amount of fresh HDPE resin may be maintained at 15% by weight in those formulations, with Formolene® HL5010 used as a secondary polymer. These polymer / masterbatch ratios may result in compositions containing about 6.75% to about 15% by weight of CNTs in the final formulation. Since polymer-CNT masterbatches are often produced using a low molecular weight polymer matrix to facilitate the dispersion of nanotubes into the polymer, the addition of Formolene® HL5010, an ultra-high molecular weight copolymer, as a secondary polymer in these compositions may result in improved chemical resistance of the resulting material to electrolyte solutions used in batteries, as well as improved impact strength and ductility of the final composition.

[0042] In some embodiments, relatively high surface area synthetic, high-purity graphite, and carbon black powders may be used in combination with carbon nanotubes to impart conductivity to the formulation. These HDPE-based compositions can be injection molded into plaques and tested for physical and electrical properties.

[0043] thermoplastic composition In some embodiments, the thermoplastic composition comprises (a) about 35% to about 70% by weight of a polymer resin, about 10% to about 40% by weight of synthetic graphite, and (c) about 5% to about 15% by weight of carbon nanotubes (CNTs), and about 3% to about 15% by weight of conductive carbon black powder. The polymer resin comprises at least two polymer resins, at least one of which comprises a high-density polyethylene (HDPE) polymer having a crystallinity of at least 47%, as measured by differential scanning calorimetry (DSC). The combined weight percentage values ​​of all components do not exceed 100% by weight, and all weight percentage values ​​are based on the total weight of the composition.

[0044] In certain embodiments, the HDPE polymer has a crystallinity of at least 48%, or at least 49%, or at least 50%, or at least 51%, or at least 52%, or at least 53%, or at least 54%, or at least 55%, or at least 56%, or at least 57%, or at least 58%, or at least 59%, or at least 60%, or at least 61%, as measured by DSC.

[0045] In a further embodiment, HDPE is defined as having at least 0.939 grams per cubic centimeter (g / cm³) as determined in accordance with ASTM D1505. 3 ) has a density of ). In certain embodiments, HDPE has a density of at least 0.940 g / cm³, as determined according to ASTM D1505. 3 , or at least 0.941 g / cm³ 3 , or at least 0.942 g / cm³ 3 , or at least 0.943 g / cm³ 3, or at least 0.944 g / cm³ 3 , or at least 0.945 g / cm³ 3 , or at least 0.946 g / cm³ 3 , or at least 0.947 g / cm³ 3 , or at least 0.948 g / cm³ 3 It has a density of .

[0046] Exemplary HDPE polymers that may be suitable for use in the embodiments of this disclosure include, but are not limited to, Formolene® HL5010 (Formosa Plastics), Marlex® HHM 4903 (Chevron Phillips), and Unival® DMDA-6147 (Dow). The properties of Formolene® and Marlex® HDPE are listed in Table 3. DMDA-6147 HDPE has a viscosity of 0.948 g / cm³. 3 It has a density of 59.4%, a crystallinity of 59.4%, an MFR of 10 g / 10 min (190°C, 21.6 kg, ASTM D1238), and an ESCR of over 1500 hours (100% Igepal, ASTM D1693). The crystallinity of DMDA-6147 is given by formula: Crystallinity % is calculated according to the formula: = 720.69 × density - 623.82.

[0047] In certain embodiments, the composition comprises an HDPE polymer having a crystallinity of at least 47% in an amount ranging from about 5% by weight to about 30% by weight. In certain embodiments, the composition comprises an HDPE polymer having a crystallinity of at least 47% in an amount ranging from at least 5% by weight, or at least 10% by weight, or at least 15% by weight, or less than 30% by weight, or less than 25% by weight, or less than 20% by weight.

[0048] In some embodiments, the synthetic graphite contains at least 50% of particles having a particle diameter of 4 microns (μm) to 75 μm, as determined by laser diffraction. In further embodiments, the synthetic graphite contains at least 55%, or at least 60%, or at least 65%, or at least 70%, or at least 75%, or at least 80% of particles having the enumerated particle diameters. In certain embodiments, the particles have diameters of 4 μm to 70 μm, or 4 μm to 65 μm, or 4 μm to 60 μm, or 4 μm to 55 μm, or 4 μm to 50 μm, or 5 μm to 75 μm, or 6 μm to 75 μm, or 7 μm to 75 μm, or 8 μm to 75 μm, or 9 μm to 75 μm, or 10 μm to 75 μm, or 11 μm to 75 μm, or 12 μm to 75 μm, or 13 μm to 75 μm, or 14 μm to 75 μm, or 15 μm to 75 μm, as determined by laser diffraction. In certain embodiments, it is desirable to select graphite particles within a certain range of diameters. Smaller graphite particles can result in compounds with relatively high viscosity that are over-reinforced and difficult to process using conventional melting processes. On the other hand, large graphite particles can be difficult to disperse in a homogeneous mixture with a polymer, especially when the polymer has a relatively high molecular weight.

[0049] In other embodiments, synthetic graphite is determined according to Brunauer-Emmett Teller (BET) analysis, with a yield of 5 square meters per gram (m 2 / g) Super~26m 2 It has a specific surface area (SSA) of less than 6 m / g. In some embodiments, the synthetic graphite has a specific surface area (SSA) of at least 6 m / g, as determined by BET analysis. 2 / g, or at least 7m 2 / g, or at least 8m 2 / g, or at least 9m 2 / g, or at least 10m 2 / g, or 25m 2 Less than / g, or 24m 2 Less than / g, or 23m 2 Less than / g, or 22m 2 Less than / g, or 21m 2 Less than / g, or 20m2 It has SSA less than / g

[0050] In a further embodiment, the synthetic graphite has a purity level of at least 99.5% by weight.

[0051] In some embodiments, the composition contains less than 49% by weight of carbon filler, the carbon filler comprising synthetic graphite, CNTs, and conductive carbon black powder. In certain embodiments, the composition contains less than 48% of carbon filler, or less than 47% by weight of carbon filler, or 35% to less than 49% by weight of carbon filler, or 36% to less than 49% by weight of carbon filler, or 37% to less than 49% by weight of carbon filler, or 38% to less than 49% by weight of carbon filler, or 39% to less than 49% by weight of carbon filler, or 40% to less than 49% by weight of carbon filler, or 41% to less than 49% by weight of carbon filler.

[0052] In some embodiments, the thermoplastic composition according to the embodiments of this disclosure has a volume resistivity of less than 0.45 Ohm.cm as measured according to ASTM D991. In other embodiments, the composition has a volume resistivity of less than 0.40 Ohm.cm, or less than 0.35 Ohm.cm, or less than 0.30 Ohm.cm, or less than 0.25 Ohm.cm, or less than 0.20 Ohm.cm, or less than 0.19 Ohm.cm, or less than 0.18 Ohm.cm as measured according to ASTM D991.

[0053] In a further embodiment, the composition has improved chemical resistance to zinc bromide corrosion compared to comparative compositions containing polyethylene polymers that do not have the enumerated crystallinity and / or density characteristics. Bromine is highly corrosive, breaking carbon-carbon bonds in polymers and generating acidic groups that lower the pH of the electrolyte, making it more acidic and therefore more corrosive. As described in the '362 patent (referenced above), secondary hydrogen in HDPE has been found to be far more resistant to bromination than tertiary hydrogen in polypropylene ('362 patent, 2 columns, row 56-3, row 2). Specifically, the '362 patent found that DMDA 6147 HDPE (discussed above) has suitable chemical resistance to zinc bromide corrosion. Therefore, HDPE having the crystallinity and / or density characteristics described herein was selected for use in the compositions of this disclosure.

[0054] As described herein, in some embodiments, the compositions exhibit improved chemical resistance to zinc bromide corrosion compared to comparative compositions containing polyethylene polymers that do not have the enumerated crystallinity and / or density characteristics. Chemical resistance can be evaluated according to conventional methods. For example, U.S. Patent No. 10,892,524, whose disclosure is incorporated in whole by this reference, describes pH stability experiments in which stability experiments were performed against various electrolytes to determine whether components in an electrolyte formulation were stable or experienced a significant change in pH when exposed to bromine at 60°C for 7 days. The chemical resistance of the compositions described herein can similarly be evaluated by placing a sample of the composition in an electrolyte solution containing zinc bromide and bromine at 60°C for 7 days and measuring the pH change. A composition can be considered chemically resistant if the pH of the electrolyte solution does not change by more than 1.0 after a period of 7 days.

[0055] Thermoplastic compositions according to embodiments of this disclosure may have improved processability compared to conventional compositions. In certain embodiments, the thermoplastic composition is processable (extrudeable) into sheets having a thickness of at least 7 inches (in) and 1 millimeter (mm) or less using conventional melt extrusion methods. In certain embodiments, the sheets have a thickness of less than 0.9 mm, or less than 0.8 mm, or less than 0.7 mm, or less than 0.6 mm, or between 0.4 mm and 1 mm. As used herein, processability or extrudeability means that the composition can be extruded into sheets of the indicated thickness without contaminating the extruder and / or obstructing the flow of polymer through the extruder. A composition is not extrudeable if it contaminates the extruder and / or obstructs the flow of molten extruded material.

[0056] In certain embodiments, the composition comprises about 10% to about 20% by weight of HDPE polymer, about 25% to about 40% by weight of synthetic graphite, and about 5% to about 10% by weight of CNTs.

[0057] Thermoplastic compositions according to aspects of this disclosure have the following mechanical properties: Elastic modulus of at least 4000 MPa (megapascals), as measured according to ASTM D638. Tensile stress at fracture of at least 30.5 MPa, as measured according to ASTM D638. A flexure coefficient of at least 2600 MPa, as measured according to ASTM D790. A flexural stress at fracture of at least 45 MPa, as measured according to ASTM D790, or It may have one or more specific gravities of at least 1.24, as measured according to ASTM D792.

[0058] Manufacturing method One or any of the aforementioned components described herein may first be dry-blended with each other or with any combination of the aforementioned components and then fed to an extruder from one or more feeders, or separately from one or more feeders. Fillers used in this disclosure may first be processed into a masterbatch and then fed to an extruder. Components may be fed to the extruder from a throat hopper or any side feeder.

[0059] The extruders used in this disclosure may have a single screw, multiple screws, cross-reversing co-rotating or counter-rotating screws, non-cross-reversing co-rotating or counter-rotating screws, reciprocating screws, screws with pins, screws with screens, barrels with pins, rolls, rams, helical rotors, co-mixers, disc packers, various other types of extrusion equipment, or a combination of at least one of the foregoing.

[0060] These components may also be mixed together and then melt-blended to form a thermoplastic composition. The melt-blending of the components may involve the use of shear force, tensile force, compressive force, ultrasonic energy, electromagnetic energy, thermal energy, or a combination of at least one of the aforementioned forms of force or energy.

[0061] The barrel temperature of the extruder during compounding can be set to a temperature at least a portion of the polymer that reaches its pour point (e.g., glass transition temperature) if the resin is a semicrystalline organic polymer, or if the resin is an amorphous resin.

[0062] A mixture containing the aforementioned components may be subjected to multiple blending and forming steps, if desired. For example, the thermoplastic composition may first be extruded to form pellets. The pellets may then be fed into a molding machine, where they may be formed into any desired shape or product. Alternatively, the thermoplastic composition coming out of a single molten blender may be formed into sheets or strands and subjected to post-extrusion processes such as annealing and uniaxial or biaxial orientation.

[0063] In this process, the temperature of the molten material can be kept as low as possible in some embodiments to avoid excessive thermal decomposition of the components. In certain embodiments, the melting temperature is maintained between approximately 230°C and 350°C, although higher temperatures can be used, provided that the residence time of the resin in the processing equipment is kept relatively short. In some embodiments, the molten composition exits the processing equipment, such as an extruder, through a small exit hole in the die. The resulting strands of molten resin can be cooled by passing the strands through a water bath. The cooled strands can be cut into pellets for packaging and further handling.

[0064] manufactured goods In certain embodiments, the disclosure relates to molded, formed, or shaped articles comprising thermoplastic compositions. These thermoplastic compositions can be molded into useful molded articles by various means, such as injection molding, extrusion, rotational molding, blow molding, and thermoforming, to form articles and structural components, such as metal electrode plates for flow and no-flow batteries, including zinc bromide and vanadium redox batteries. In further embodiments, the articles are bipolar plates or sheets for plate heat exchangers in fuel cells. Furthermore, in even further embodiments, the articles may replace metal and metallized polymer materials in EMI shielding for coaxial cables, mobile phones, computers, laptops, monitors, and other highly sensitive electronic devices requiring insulation from external electromagnetic fields.

[0065] In certain embodiments, the article is a sheet having a thickness of 1 mm or less. In certain embodiments, the sheet has a thickness of less than 0.9 mm, or less than 0.8 mm, or less than 0.7 mm, or less than 0.6 mm, or between 0.4 mm and 1 mm.

[0066] Various combinations of elements of this disclosure, such as combinations of elements from dependent claims that depend on the same independent claim, are encompassed by this disclosure.

[0067] The nature of this disclosure In various aspects, this disclosure includes, with respect to at least the following aspects: Embodiment 1. A thermoplastic composition, A polymer resin comprising approximately 35% to approximately 70% by weight, wherein the polymer resin comprises at least two polymer resins, and at least one of the polymer resins comprises a high-density polyethylene (HDPE) polymer having a crystallinity of at least 47%, as measured by differential scanning calorimetry (DSC), Approximately 10% to 40% by weight of synthetic graphite, Approximately 5% to 15% by weight of carbon nanotubes (CNTs), Approximately 3% to 15% by weight of conductive carbon black powder, and comprising, consisting of, or essentially consisting of, A thermoplastic composition in which the combined weight percentage of all components does not exceed 100% by weight, and all weight percentages are based on the total weight of the composition. Embodiment 2. The thermoplastic composition according to Embodiment 1, wherein the HDPE has a crystallinity of at least 55% as measured by differential scanning calorimetry (DSC). Embodiment 3. HDPE is determined in accordance with ASTM D1505 to be at least 0.939 g / cm³. 3 A thermoplastic composition according to embodiment 1 or 2, having a density of . Embodiment 4. The thermoplastic composition according to any one of Embodiments 1 to 3, wherein the synthetic graphite comprises at least 50% particles having a particle diameter of 4 microns (μm) to 75 μm, as determined by laser diffraction. Appearance 5. The synthetic graphite is determined according to Brunauer-Emmett Teller (BET) analysis, 5m 2 / g super~26m 2 A thermoplastic composition according to any one of embodiments 1 to 4, having a specific surface area of ​​less than / g. Embodiment 6. The thermoplastic composition according to any one of Embodiments 1 to 5, wherein the synthetic graphite has a purity level of at least 99.5% by weight. Embodiment 7. A thermoplastic composition according to any one of Embodiments 1 to 6, wherein the composition comprises less than 49% by weight of carbon filler, and the carbon filler comprises synthetic graphite, CNTs, and conductive carbon black powder. Embodiment 8. A thermoplastic composition according to any one of Embodiments 1 to 7, wherein the composition has a volume resistivity of less than 0.45 Ohm.cm as measured according to ASTM D991. Embodiment 9. A thermoplastic composition according to any one of Embodiments 1 to 8, wherein the composition has improved chemical resistance to zinc bromide corrosion compared to a comparative composition comprising a polyethylene polymer having a crystallinity of less than 47% instead of an HDPE polymer having a crystallinity of at least 47%. Embodiment 10. The thermoplastic composition according to any one of Embodiments 1 to 9, wherein the composition can be extruded into a sheet having a width of at least 7 inches and a thickness of 1 mm or less using a conventional melt extrusion method. Embodiment 11. A thermoplastic composition according to any one of Embodiments 1 to 10, wherein the composition comprises a high-density polyethylene (HDPE) polymer having a crystallinity of at least 47% in an amount of about 5% to about 30% by weight. Embodiment 12. The composition is An HDPE polymer having a crystallinity of at least 47% and approximately 10% to 20% by weight, Approximately 25% to 40% by weight of synthetic graphite, A thermoplastic composition according to any one of embodiments 1 to 11, comprising approximately 5% to approximately 10% by weight of carbon nanotubes (CNTs). Embodiment 13. The composition is Elastic modulus of at least 4000 MPa, as measured according to ASTM D638. Tensile stress at fracture of at least 30.5 MPa, as measured according to ASTM D638. A flexure coefficient of at least 2600 MPa, as measured according to ASTM D790. A flexural stress at fracture of at least 45 MPa, as measured according to ASTM D790, or A thermoplastic composition according to any one of embodiments 1 to 12, having a specific gravity of at least 1.24 as measured in accordance with ASTM D792. Embodiment 14. An article comprising the composition described in any of Embodiments 1 to 13. Embodiment 15. The article according to Embodiment 14, wherein the article is a sheet having a thickness of 1 mm or less. Embodiment 16. The article according to Embodiment 14 or 15, wherein the article is a battery electrode plate, a bipolar plate for a fuel cell, or a sheet for a plate heat exchanger. [Examples]

[0068] The following examples are provided to those skilled in the art to provide a complete disclosure and description of how the compounds, compositions, articles, devices, and / or methods claimed herein are prepared and evaluated, and are intended to be purely illustrative and not to limit the disclosure. While efforts have been made to ensure accuracy with respect to numerical values ​​(e.g., quantities, temperatures, etc.), some error and deviation should be taken into consideration. Unless otherwise specified, parts are by weight, temperatures are in degrees Celsius or ambient temperature, and pressures are atmospheric pressure or near atmospheric pressure. Unless otherwise specified, percentages relating to compositions are in weight percent.

[0069] There are many variations and combinations of other reaction ranges and conditions that can be used to optimize reaction conditions, such as component concentrations, desired solvents, solvent mixtures, temperature, pressure, and the purity and yield of the product obtained from the described process. Optimizing such process conditions will only require reasonable and routine experiments.

[0070] The compositions described herein contain one or more of the components shown in Table 2. [Table 2]

[0071] Table 3 lists several polyethylene resins that have been evaluated for compositions according to embodiments of this disclosure. [Table 3]

[0072] Formolene and Marlex HDPE have sufficient density and crystallinity to be suitable for use in the embodiments of this disclosure. Primatop MDPE has better flow properties than Formolene HDPE, but also has lower density and crystallinity. This polymer has low chemical resistance to bromination, and is therefore assumed to be unsuitable for use in applications such as zinc bromide battery electrode plates. Accordingly, polyethylenes with higher density and / or crystallinity are more suitable for compositions in the embodiments of this disclosure.

[0073] As shown in Table 4, various types of graphite fillers were evaluated. [Table 4]

[0074] Graphite was selected to balance its conductivity with flow / processability. Synthetic graphite Asbury 1125 was unsuitable due to its large average particle size (approximately 75% of particles having a size of 75–150 μm) and relatively high impurity levels. Timrex® KS44 synthetic graphite has a purity level of at least 99.5 wt% with less than 0.5 wt% impurities. Timrex® KS4 synthetic graphite had a low impurity level, but its average particle size was too low for the desired application (approximately 4 μm for D90). Graphite is desirable to have a relatively large particle size compared to other carbon fillers used in the described composition, and in terms of specific surface area, graphite has the largest particle size, followed by carbon nanotubes, and finally carbon black powder. This mixture of particles of different sizes (multimodal distribution of particles) increases the volume fraction for maximum packing of carbon fillers in the resin. Compared to a monomodal distribution of particles (where all particles are the same size), mixing particles of different sizes results in a reduction in the viscosity of the final composition for the same total carbon content, improving the flow and processability of the material. Therefore, synthetic graphite having a medium particle size (80% of particles between 4 and 45 μm) was selected for the compositions described herein.

[0075] The compositions were prepared according to the formulations listed in Table 5. [Table 5]

[0076] The compositions listed in Table 5 were formulated, and all compositions except C1.5 were extrudeable. Comparative composition C1.5, containing 28 wt% graphite and 12 wt% carbon black, was not extrudeable because the strands were rough to the touch and visibly rough, the extruded strands constantly surging in the die, and any tension on the strands caused them to snap. Samples of composition C1.5 could not be collected for molding and testing.

[0077] The following extrusion conditions were used. • Feed rate (pounds per hour, lb / hr): 20 for C1.2, C1.3, and C1.4, and 25 for Ex1.1, Ex1.2, Ex1.3, Ex1.4, and Ex1.5. Screw speed (revolutions per minute, RPM): 300. Torque (%): 81 (C1.2), 79 (C1.3, C1.4), 75 (Ex1.1, Ex1.2), 77 (Ex1.3), 81 (Ex1.4), and 86 (Ex1.5). • Vent (die end, barrel 10) (inches of mercury column, in Hg) (all compositions): 20. Temperature profile (°F) (all compositions): 550 (Zone 1), 570 (Zones 2-9), and 570 (Die). Both the HDPE polymer and the HDPE-CNT masterbatch were supplied in barrel 1 through the feed throat of the extruder, carbon black was supplied in barrel 4, and graphite was supplied in barrel 6.

[0078] Various properties of the extruded composition are evaluated, and the results are described in Tables 6A and 6B. [Table 6] [Table 7]

[0079] Figures 1 to 7 show graphical representations of various properties of the compositions. As demonstrated in the figures and Tables 6A and 6B, compositions Ex1.1 to Ex1.5 of this disclosure exhibited an elastic modulus of at least 4000 MPa (ASTM D638), a tensile stress at break of at least 30.5 MPa (ASTM D638), a flexural modulus of at least 2600 MPa (ASTM D790), a flexural stress at break of at least 45 MPa (ASTM D790), a specific gravity of at least 1.24 (ASTM D792), and a volume electrical resistivity of 0.3 Ohm.cm or less (ASTM D991).

[0080] The above description is intended to be illustrative, not restrictive. For example, the examples (or one or more of their embodiments) described above may be used in combination with one another. Other embodiments may be used by those skilled in the art after considering the above description. The abstract is provided in accordance with 37 CFR §1.72(b) to enable the reader to quickly confirm the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the claims or their meaning. Also, in the detailed description above, various features may be grouped together to streamline the disclosure. This should not be interpreted as meaning that any disclosed features not claimed are essential to any claim. Rather, the subject matter of the invention may be less than all the features of a particular disclosed embodiment. Thus, the following claims are incorporated into the detailed description as examples or embodiments, and each claim is intended to stand independently as a distinct embodiment, and such embodiments may be combined with one another in various combinations or permutations. The scope of the disclosure should be determined by reference to the appended claims, together with the entire scope of equivalents to which such claims are granted.

Claims

1. A thermoplastic composition, A polymer resin comprising approximately 35% to approximately 70% by weight, wherein the polymer resin comprises at least two polymer resins, and at least one of the polymer resins comprises a high-density polyethylene (HDPE) polymer having a crystallinity of at least 47%, as measured by differential scanning calorimetry (DSC), Approximately 10% to 40% by weight of synthetic graphite, Approximately 5% to 15% by weight of carbon nanotubes (CNTs), It contains approximately 3% to 15% by weight of conductive carbon black powder, A thermoplastic composition in which the combined weight percentage of all components does not exceed 100% by weight, and all weight percentages are based on the total weight of the composition.

2. The thermoplastic composition according to claim 1, wherein the HDPE has a crystallinity of at least 55% as measured by differential scanning calorimetry (DSC).

3. The HDPE is determined according to ASTM D1505, and is at least 0.939 g / cm³. ３ A thermoplastic composition according to claim 1 or 2, having a density of .

4. The thermoplastic composition according to any one of claims 1 to 3, wherein the synthetic graphite comprises at least 50% particles having a particle diameter of 4 microns (μm) to 75 μm, as determined by laser diffraction.

5. The synthetic graphite is determined according to Brunauer-Emmett Teller (BET) analysis, 5m ２ / g over 26m ２ A thermoplastic composition according to any one of claims 1 to 4, having a specific surface area of ​​less than / g.

6. The thermoplastic composition according to any one of claims 1 to 5, wherein the synthetic graphite has a purity level of at least 99.5% by weight.

7. The thermoplastic composition according to any one of claims 1 to 6, wherein the composition comprises less than 49% by weight of carbon filler, and the carbon filler comprises the synthetic graphite, the CNT, and the conductive carbon black powder.

8. The thermoplastic composition according to any one of claims 1 to 7, wherein the composition has a volume resistivity of less than 0.45 Ohm.cm as measured according to ASTM D991.

9. The thermoplastic composition according to any one of claims 1 to 8, wherein the composition has improved chemical resistance to zinc bromide corrosion compared to a comparative composition comprising a polyethylene polymer having a crystallinity of less than 47% instead of the HDPE polymer having a crystallinity of at least 47%.

10. The thermoplastic composition according to any one of claims 1 to 9, wherein the composition can be extruded into a sheet having a width of at least 7 inches and a thickness of 1 mm or less using a conventional melt extrusion method.

11. The thermoplastic composition according to any one of claims 1 to 10, wherein the composition comprises a high-density polyethylene (HDPE) polymer having a crystallinity of at least 47% in an amount of about 5% to about 30% by weight.

12. The composition is The HDPE polymer having a crystallinity of at least 47% in an amount of approximately 10% to approximately 20% by weight, Approximately 25% to 40% by weight of the aforementioned synthetic graphite, A thermoplastic composition according to any one of claims 1 to 11, comprising about 5% to about 10% by weight of CNTs.

13. The composition is Elastic modulus of at least 4000 MPa, as measured according to ASTM D638, A tensile stress at fracture of at least 30.5 MPa, as measured according to ASTM D638. A coefficient of inflection of at least 2600 MPa, as measured according to ASTM D790. A flexural stress at fracture of at least 45 MPa, as measured according to ASTM D790, or A thermoplastic composition according to any one of claims 1 to 12, having a specific gravity of at least 1.24 as measured according to ASTM D792.

14. An article comprising the composition according to any one of claims 1 to 13,

15. The article according to claim 14, wherein the article is a sheet having a thickness of 1 mm or less, or the article is a battery electrode plate, a bipolar plate for a fuel cell, or a sheet for a plate heat exchanger.

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