Conductive composition for battery electrode plates

Abstract

An embodiment of the present disclosure is a composite material comprising: about 35 wt% to about 70 wt% of at least one polyethylene polymer; about 25 wt% to about 55 wt% of at least one graphite filler; and at least 50 square meters per gram (m 2 and about 2 wt % to about 15 wt % of a carbon powder filler having a BET surface area of ​​at least 0.94 grams per cubic centimeter (g / cm 3 ). 3 ), a melt flow rate (MFR) of at least 10 grams per 10 minutes (g / 10 min) measured at 190° C. and 21.6 kilograms (kg), and an environmental stress crack resistance (ESCR) of at least 500 hours. The composition has a volume electrical resistivity of less than 5 ohm-centimeters (ohm-cm) and an MFR of at least 4 g / 10 min measured at 280° C. and 21.6 kg.

Description

[Technical Field]

[0001] The present disclosure relates to thermoplastic compositions having high electrical conductivity, and in particular to polyethylene-based compositions containing graphite filler and carbon powder that are suitable for use in battery electrode applications. [Background technology]

[0002] Carbon-plastic electrode compositions for use as electrode plates in zinc bromide batteries have long been sought. For example, U.S. Patent No. 4,169,816 ("the '816 patent") to Exxon Research & Engineering describes a homogeneous blend of crystalline polypropylene-ethylene copolymer, conductive carbon black, a small amount of silica, and a fibrous reinforcing agent selected from carbon fiber and a mixture of carbon and glass fibers. One example composition is reported to have excellent strength, good extrudability, excellent volume resistivity (1 ohm-cm), and good impermeability. The '816 patent specifies that to impart electrical conductivity, the composition should preferably contain at least 15 parts by weight of finely divided conductive carbon powder per 100 parts per hundred (pph) of copolymer. Furthermore, it is desirable to avoid using conductive carbon up to 35 pph, otherwise the composition would be too brittle and difficult to extrude into thin, nonporous sheets. Additionally, high carbon content tends to increase the permeability of thin sheets made from such compositions to liquids, such as, by way of example, bromine.

[0003] Johnson Controls began researching plastic-carbon electrodes in the 1990s and reported at the time that polypropylene-ethylene copolymer-based electrodes developed by Exxon were susceptible to oxidative attack, swelling, and warping. The mechanism behind bromide attack was attributed to the vulnerability of tertiary hydrogens in the backbone of the propylene chain. To circumvent this problem, Johnson Controls selected high-density polyethylene (HDPE) homopolymer, which was found to remove most, if not all, of the tertiary hydrogens on the backbone chain. Johnson Controls reported positive results in aging studies using substitutions in the base polymer, showing that HDPE outperformed ethylene-propylene (EP) copolymers.

[0004] U.S. Patent No. 5,173,362 (the "'362 Patent"), issued to Globe-Union Inc. in December 1992, describes compositions for HDPE-based carbon-plastic electrodes and electrode systems, particularly those to be used in bipolar electrodes in zinc-bromine batteries. These compositions preferably contain carbon black as a conductive filler in a polymer matrix, along with a reinforcing material such as glass fiber. Prior art studies have shown that zinc-bromine electrodes tend to warp, believed to be caused by physical expansion of the electrode due to bromine absorption by the electrode material. The compositions and manufacturing process described in this invention essentially eliminate this problem. In the '362 Patent, materials are prepared using a lamination or slurry process. Bromination, unlike chlorination, is highly selective for the chemistry of the polymer matrix used; tertiary hydrogens in polypropylene react with bromine approximately 20,000 times faster than secondary hydrogens in polyethylene. Three carbon blacks were used in the compositions of the present invention, with the Ketjenblack EC 300J grade providing the best combination of conductivity and processability properties for the amount of carbon used.

[0005] The '362 patent claims "a bipolar battery substrate comprising about 10 to 70 weight percent glass fiber, about 5 to 40 wt. % carbon black, and the remainder being resin." The '362 patent claims "a bipolar battery substrate comprising: a thermoplastic resin, a glass fiber filler, and conductive carbon black powder, the conductive carbon black powder being prepared by a process including the following steps: compounding a mixture of the resin and the conductive powder; providing at least one fiber mat of the glass fiber filler; conveying the mat along a linear path; introducing the molten compounded resin and powder onto the mat; pressing the mat to impregnate it with the molten resin containing the conductive powder; and cooling the impregnated mat to form a sheet substrate." The bipolar battery substrate includes about 10 to 70 weight percent glass fiber, about 5 to 40 wt. % carbon black, and the remainder being resin." Despite the broad claims regarding carbon fiber loading, Table 4 of the patent lists a carbon loading of 18 wt% (the same as Exxon), and therefore the carbon and fiber loadings used in the Johnson Controls patent are presumably close to those disclosed in Exxon's '816 patent.

[0006] Thus, formulations containing high density polyethylene and different carbon sources have been described in the prior art, but none have exhibited the balance of electrical conductivity, chemical resistance, and processability required to produce thin sheets for battery electrode plates using conventional sheet extrusion processes.

[0007] These and other shortcomings are addressed by aspects of the present disclosure. Summary of the Invention [Means for solving the problem]

[0008] Embodiments of the present disclosure include a PET film comprising: about 35 wt% to about 70 wt% of at least one polyethylene polymer; about 25 wt% to about 55 wt% of at least one graphite filler; and a porosity of at least 50 grams per square meter (m ) as determined in accordance with ASTM D3037. 2and about 2 wt % to about 15 wt % of a carbon powder filler having a BET surface area of ​​at least 0.94 grams per cubic centimeter (g / cm / g), as determined in accordance with ASTM D1505. 3 ), a melt flow rate (MFR) of at least 10 grams per 10 minutes (g / 10 min) as measured at 190°C and 21.6 kilograms (kg) according to ASTM D1238, and an environmental stress crack resistance (ESCR) of at least 500 hours as measured in 100% Igepal solution according to ASTM D1693. The composition has a volume electrical resistivity of less than 5 ohm-centimeters (ohm-cm) as measured according to ASTM D991 or ASTM D257, and an MFR of at least 4 g / 10 min as measured at 280°C and 21.6 kg according to ASTM D1238. The sum of weight percentages of all components does not exceed 100 wt%, and all weight percentages are based on the total weight of the composition.

[0009] A further aspect of the present disclosure is a composite material comprising about 35 wt% to about 70 wt% of at least one polyethylene polymer, about 25 wt% to about 55 wt% of at least one graphite filler, and a porosity of at least 50 grams per square meter (m ) determined in accordance with ASTM D3037. 2 % to about 15 wt. % of a carbon powder filler having a BET surface area of ​​at least 0.94 grams per cubic centimeter (g / cm 3 / g). The method includes combining at least one polyethylene polymer, at least one graphite filler, and the carbon powder filler to form a mixture; and extruding the mixture to form the composition. The polyethylene polymer has a BET surface area of ​​at least 0.94 grams per cubic centimeter (g / cm 3 / g) as determined in accordance with ASTM D1505. 3), a melt flow rate (MFR) of at least 10 grams per 10 minutes (g / 10 min) as measured at 190°C and 21.6 kilograms (kg) according to ASTM D1238, and an environmental stress crack resistance (ESCR) of at least 500 hours as measured in 100% Igepar solution according to ASTM D1693. Compositions formed according to this method have a volume electrical resistivity of less than 5 ohm-centimeters (ohm-cm) as measured according to ASTM D991 or ASTM D257, and an MFR of at least 4 g / 10 min as measured at 280°C and 21.6 kg according to ASTM D1238. The sum of weight percentages of all components does not exceed 100 wt%, and all weight percentages are based on the total weight of the composition.

[0010] The drawings are not necessarily drawn to scale, and in the drawings, like numerals may describe like components in different views. Like numerals with different letter suffixes may represent different instances of like components. The drawings illustrate generally by way of example, but not by way of limitation, various aspects discussed herein. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a graph illustrating melt flow and volume resistivity for comparative compositions and exemplary compositions formed according to embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] This disclosure relates to a highly filled plastic material that replaces titanium in the electrode plates of zinc bromide flow batteries. This disclosure relates to a composition comprising at least one high-density polyethylene and a mixture of synthetic graphite and conductive carbon black in different ratios. This composition has good electrical conductivity, chemical resistance, and the ability to be processed into thin plastic sheets using conventional polymer processing methods.

[0013] In certain embodiments, the polyethylene is a medium- to high-density ethylene-hexene copolymer. Synthetic high-purity graphite and carbon black powders of varying particle sizes were used as fillers to impart electrical conductivity to the formulations of the present invention. These PE-graphite-carbon compositions were injection molded into plaques and extruded into sheets of varying thicknesses and successfully used to fabricate electrode plates for zinc bromide batteries.

[0014] The choice of polymer matrix affects the composition's chemical resistance to the electrolyte solution used in flow batteries, with low-density polyethylene generally found to be poorly responsive to the environmental conditions encountered by electrode plate materials within batteries. In contrast, high-density polyethylene and hexene copolymers with at least 45% crystallinity have excellent resistance to zinc bromide at the relatively high operating temperatures of batteries. Graphite suitable for use in embodiments of the present disclosure is a highly pure, crystalline material produced at ultra-high temperatures by vaporizing metal oxides, sulfur, iron, aluminum, and many other impurities to produce artificial graphite of 99%+ purity carbon with particle sizes ranging from less than 1 micron to several hundred microns. The carbon filler used in embodiments of the present disclosure has a primary / elementary particle size of 10-50 nm, with aggregates several hundred nanometers in size and larger aggregates of 100-200 microns.

[0015] Before the present compounds, compositions, articles, systems, devices, and / or methods are disclosed and described, it is to be understood that they are not limited to particular synthetic methods unless otherwise specified, or to particular reagents unless otherwise specified, and as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0016] Various combinations of elements of the present disclosure are encompassed by the present disclosure, for example combinations of elements from dependent claims that are dependent on the same independent claim.

[0017] Furthermore, unless expressly stated otherwise, it is understood that it is in no way intended that any method described herein be construed as requiring that its steps be performed in a specific order. Thus, where a method claim does not actually recite the order in which its steps are to be followed, or where the claim or the specification does not otherwise specifically indicate that the steps are limited to a specific order, no order is intended to be inferred in any respect. This applies to matters of logic regarding the arrangement of steps or operational flow; the plain meaning derived from grammatical construction or punctuation; and any possible implicit basis for interpretation, including the number or type of aspects described in the specification.

[0018] All publications mentioned herein are incorporated by reference to disclose and describe the methodologies and / or materials in connection with which the publications are cited. definition

[0019] It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in this specification and claims, the term "comprising" can include the embodiments of "consisting of" and "consisting essentially of." Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In this specification and in the appended claims, reference will be made to several terms that are intended to be defined herein.

[0020] As used herein and in the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a "polyethylene polymer" includes a mixture of two or more polyethylene polymers.

[0021] As used herein, the term "combination" is inclusive of blends, mixtures, alloys, reaction products, and the like.

[0022] Ranges can be expressed herein as from one value (first value) to another value (second value). When such a range is expressed, the range, in some embodiments, includes one or both of the first and second values. Similarly, when values ​​are expressed as approximations, it is understood that the particular value forms another embodiment by use of the antecedent "about." It is further understood that the endpoints of each range are valid values ​​both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are multiple values ​​disclosed herein, and that each value is also disclosed herein as "about" that value in addition to the particular value itself. For example, if the value "10" is disclosed, then "about 10" is also disclosed. It is also understood that each unit between two specified units is also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0023] As used herein, the terms "about" and "at or near" mean that the quantity or value in question can be the specified value, approximately the specified value, or nearly the same as the specified value. As used herein, unless otherwise indicated or inferred, it is generally understood to be a variation of ±10% of the nominal value indicated. This term is intended to convey that an equivalent result or effect as recited in the claims is facilitated by a similar value. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but can be approximate and / or larger or smaller as desired, reflecting tolerances, conversion factors, rounding, measurement errors, and the like, as well as other factors known to those skilled in the art. In general, amounts, sizes, formulations, parameters, or other quantities or characteristics are "about" or "approximate," whether or not expressly stated as such. When "about" is used before a quantitative value, the parameter is also understood to include the specific quantitative value itself, unless specifically stated otherwise.

[0024] Disclosed are the components used to prepare the disclosed compositions, as well as the compositions themselves used within the methods disclosed herein. Because these and other materials are disclosed herein, when combinations, subsets, interactions, groups, etc. of these materials are disclosed, it is understood that each is specifically contemplated and described herein, even if specific reference to each of the various individual and collective combinations and permutations of these compounds may not be explicitly disclosed. For example, when particular compounds are disclosed and discussed, and multiple modifications that can be made to molecules comprising those compounds are discussed, what is specifically contemplated are each and every combination and permutation of those compounds, as well as modifications thereof that are possible unless specifically indicated to the contrary. Thus, when a class of molecules A, B, and C is disclosed, as well as a class of molecules D, E, and F, and an example of a combined molecule, AD, is disclosed, each is individually and collectively contemplated, even if not individually mentioned, meaning that the combinations AE, AF, BD, BE, BF, CD, CE, and CF are considered to be disclosed. Similarly, any subsets or combinations of these are also disclosed. Thus, for example, the subgroups AE, BF, and CE could be considered disclosed. This concept applies to all aspects of this application, including, but not limited to, steps in methods of making and using the disclosed compositions. Thus, where there are various additional steps that can be performed, it is understood that each of these additional steps can be performed with any specific aspect or combination of aspects of the disclosed methods.

[0025] References in this specification and the appended claims to parts by weight of a particular component or ingredient in a composition or article indicate the weight relationship between the component or ingredient to which the parts by weight are expressed and any other component or ingredient in the composition or article. Thus, in a compound containing 2 parts by weight of component X and 5 parts by weight of component Y, X and Y are present in a weight ratio of 2:5, and are present in such ratio regardless of whether additional components are included in the compound.

[0026] Weight percent of a component is based on the total weight of the formulation or composition in which the component is included, unless specifically stated to the contrary.

[0027] As used herein, the term "number average molecular weight" or "M n " can be used interchangeably and refers to the statistical average molecular weight of all polymer chains in a sample and is expressed by the formula:

number

[0028] As used herein, the term "weight average molecular weight" or "M w " can be used interchangeably, and the formula:

number

[0029] As used herein, the terms "molecular weight dispersity index" or "PDI" may be used interchangeably and are defined by the formula:

number

[0030] The terms "residue" and "structural unit" used in reference to constituent parts of a polymer are synonymous throughout this specification.

[0031] As used herein, the terms "weight percent," "wt%," and "wt%" can be used interchangeably and refer to the weight percent of a given component based on the total weight of the composition, unless otherwise specified. That is, all wt% values ​​are based on the total weight of the composition, unless otherwise specified. It is understood that the sum of the wt% values ​​of all components in a disclosed composition or formulation equals 100.

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

[0033] Each of the materials disclosed herein is commercially available and / or methods for its preparation are known to those skilled in the art.

[0034] It is understood that the compositions disclosed herein have specific functions, and while disclosed herein are specific structural requirements for performing the disclosed functions, it is understood that there are a variety of structures that can perform the same functions related to the disclosed structures, and that these structures will typically achieve the same results. composition

[0035] Embodiments of the present disclosure include a PET film comprising: about 35 wt% to about 70 wt% of at least one polyethylene polymer; about 25 wt% to about 55 wt% of at least one graphite filler; and a porosity of at least 50 grams per square meter (m ) as determined in accordance with ASTM D3037. 2 and about 2 wt % to about 15 wt % of a carbon powder filler having a BET surface area of ​​at least 0.94 grams per cubic centimeter (g / cm / g), as determined in accordance with ASTM D1505. 3 ), a melt flow rate (MFR) of at least 10 grams per 10 minutes (g / 10 min) as measured at 190°C and 21.6 kilograms (kg) according to ASTM D1238, and an environmental stress crack resistance (ESCR) of at least 500 hours as measured in 100% Igepar solution according to ASTM D1693. Additionally, the composition has a volume electrical resistivity of less than 5 ohm-centimeters (ohm-cm) as measured according to ASTM D991 or ASTM D257, and the composition has an MFR of at least 4 g / 10 min as measured at 280°C and 21.6 kg according to ASTM D1238. The sum of the weight percentages of all components does not exceed 100 wt%, and all weight percentages are based on the total weight of the composition.

[0036] In some embodiments, the polyethylene polymer comprises a copolymer comprising ethylene and hexene monomers. Combinations of polyethylene polymers and / or copolymers may also be used. Examples of such copolymers include, but are not limited to, Formolene® HL5010, Primatop™ MDPE 003938, and Marlex® HHM 4903. In further embodiments, the polyethylene polymer comprises a copolymer comprising ethylene monomer and one or more monomers, including, but not limited to, 1-butene, 1-hexene, 1-octene, 1-decene, 1-octadecene, and 4-methyl-1-pentene.

[0037] In certain embodiments, the polyethylene polymer has a crystallinity of at least 50% as determined by differential scanning calorimetry (DSC). In further embodiments, the polyethylene polymer has a crystallinity of 50% to 95% as determined by differential scanning calorimetry (DSC). In specific embodiments, the polyethylene polymer has a crystallinity of 50% to 90%, 50% to 70%, 50% to 61%, or 50% to 60%.

[0038] The graphite filler may be synthetic graphite in some embodiments. Exemplary graphite fillers include, but are not limited to, Asbury 1125, TIMREX® KS4, TIMREX® KS44, and combinations thereof.

[0039] As discussed herein, the carbon powder filler has a density of at least 50 grams per square meter (m ) as determined in accordance with ASTM D3037. 2 / g). In a further embodiment, the carbon powder filler has a BET surface area of ​​at least 60 square meters per gram (m / g) as determined in accordance with ASTM D3037. 2 / g) BET surface area.

[0040] Compositions according to embodiments of the present disclosure may also have good thermal conductivity properties, which are affected by the type and loading level of filler, which in turn affect extrusion / sheet forming properties.

[0041] In some embodiments, the composition may be extruded into a sheet. In further embodiments, the composition may be formed by extrusion, injection molding, compression molding, injection-compression molding, thermoforming, or some combination of these processes. Sheets of various thicknesses may be formed. In some embodiments, the composition may be formed into sheets having thicknesses of up to 3 mm or more. In further embodiments, thin sheets of 0.020" to 0.060" may be formed. As discussed herein, extrusion may be a desirable process for producing these thin sheets. Manufacturing method

[0042] 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 into the extruder from a single or multiple feeder, or fed separately from a single or multiple feeder. The fillers used in the present disclosure may also be first processed into a masterbatch and then fed into the extruder. The components may be fed into the extruder from a throat hopper or any side feeder.

[0043] The extruder used in this disclosure may have a single screw, multiple screws, intermeshing co-rotating or counter-rotating screws, non-intermeshing co-rotating or counter-rotating screws, reciprocating screws, pinned screws, screened screws, pinned barrels, rolls, rams, helical rotors, co-kneaders, disc-pack processors, various other types of extrusion equipment, or a combination comprising at least one of the foregoing.

[0044] The components may also be mixed together and then melt-blended to form the thermoplastic composition. Melt-blending the components may involve the use of shear force, extensional force, compression force, ultrasonic energy, electromagnetic energy, thermal energy, or a combination comprising at least one of the foregoing forms of force or energy.

[0045] The barrel temperature of the extruder during compounding can be set to a temperature at which at least a portion of the polymer reaches a temperature about equal to or higher than the melting temperature if the resin is a semi-crystalline organic polymer, or to the pour point (e.g., glass transition temperature) if the resin is an amorphous resin.

[0046] 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 and formed into pellets. The pellets may then be fed to a molding machine where they may be formed into any desired shape or product. Alternatively, the thermoplastic composition exiting a single melt blender may be formed into sheets or strands and subjected to post-extrusion processes such as annealing, uniaxial or biaxial orientation, etc.

[0047] The temperature of the melt in this process may be kept as low as possible in some embodiments to avoid excessive thermal degradation of the components. In certain embodiments, the melt temperature is maintained between about 230°C and about 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 melt-processed composition exits the processing equipment, such as an extruder, through small exit holes in a die. The resulting strands of molten resin may be cooled by passing them through a water bath. The cooled strands can be cut into pellets for packaging and further handling.

[0048] The composition may be formed into a sheet as described herein. manufactured goods

[0049] In certain embodiments, the present disclosure relates to formed, formed, or molded articles comprising the thermoplastic compositions or sheets made therefrom. The thermoplastic compositions can be molded into useful shapes by a variety of means, such as injection molding, extrusion, rotational molding, blow molding, and thermoforming, to form articles and structural components for electronic devices, including, but not limited to, energy storage batteries, battery electrodes, plates for heat exchangers, personal or commercial electronic devices, such as cell phones, tablet computers, personal computers, notebooks, and portable computers, and other such devices, medical applications, RFID applications, automotive applications, and the like. In a further embodiment, the article is extruded. In yet another embodiment, the article is injection molded.

[0050] Various combinations of elements of the present disclosure are encompassed by the present disclosure, for example combinations of elements from dependent claims that are dependent on the same independent claim. Aspects of the disclosure

[0051] In various aspects, the present disclosure relates to and includes at least the following aspects:

[0052] Aspect 1. About 35 wt% to about 70 wt% of at least one polyethylene polymer; about 25 wt% to about 55 wt% of at least one graphite filler; At least 50 grams per square meter (m) determined in accordance with ASTM D3037 2 % to about 15 wt. % of a carbon powder filler having a BET surface area of ​​0.01 wt. / g; A composition comprising, consisting of, or consisting essentially of Polyethylene polymers have a viscosity of at least 0.94 grams per cubic centimeter (g / cm) as determined in accordance with ASTM D1505 3 ), a melt flow rate (MFR) of at least 10 grams per 10 minutes (g / 10 min) measured at 190°C and 21.6 kilograms (kg) according to ASTM D1238, and an environmental stress crack resistance (ESCR) of at least 500 hours measured in a 100% Igepar solution according to ASTM D1693; the composition has a volume electrical resistivity of less than 5 ohm-centimeters (ohm-cm), measured in accordance with ASTM D991 or ASTM D257; the composition has a MFR of at least 4 g / 10 min measured at 280°C and 21.6 kg according to ASTM D1238; A composition wherein the total weight percentage of all components does not exceed 100 wt%, and all weight percentages are based on the total weight of the composition.

[0053] Embodiment 2. The composition of embodiment 1, wherein the polyethylene polymer comprises a copolymer comprising ethylene and hexene monomers.

[0054] Embodiment 3. The composition of embodiment 1, wherein the polyethylene polymer comprises a copolymer comprising ethylene monomer and one or more monomers selected from the group consisting of 1-butene, 1-hexene, 1-octene, 1-decene, 1-octadecene, and 4-methyl-1-pentene.

[0055] Embodiment 4. The composition of any one of embodiments 1 to 3, wherein the polyethylene polymer has a crystallinity of at least 50% as determined by differential scanning calorimetry (DSC).

[0056] Embodiment 5. The composition of embodiment 4, wherein the polyethylene polymer has a crystallinity of 50% to 95% as determined by differential scanning calorimetry (DSC).

[0057] Embodiment 6. The composition of any one of embodiments 1 to 5, wherein the graphite is synthetic graphite.

[0058] Aspect 7. The carbon powder filler has a density of at least 60 grams per square meter (m) as determined in accordance with ASTM D3037. 2 7. The composition of any one of embodiments 1 to 6, having a BET surface area of ​​1 / g.

[0059] Embodiment 8. An extruded sheet comprising the composition of any one of embodiments 1 to 7.

[0060] Embodiment 9. The extruded sheet of embodiment 8, having a thickness of 0.020 inches to 0.060 inches.

[0061] Embodiment 10. A composite material comprising about 35 wt% to about 70 wt% of at least one polyethylene polymer, about 25 wt% to about 55 wt% of at least one graphite filler, and a surface roughness of at least 50 grams per square meter (m), as determined in accordance with ASTM D3037. 2 1. A method for forming a composition comprising, consisting of, or consisting essentially of: about 2 wt % to about 15 wt % of a carbon powder filler having a BET surface area of ​​1000 nm to 1500 nm / g; combining at least one polyethylene polymer, at least one graphite filler, and a carbon powder filler to form a mixture; extruding the mixture to form a composition; comprising, consisting of, or consisting essentially of Polyethylene polymers have a viscosity of at least 0.94 grams per cubic centimeter (g / cm) as determined in accordance with ASTM D1505 3 ), a melt flow rate (MFR) of at least 10 grams per 10 minutes (g / 10 min) as measured at 190°C and 21.6 kilograms (kg) according to ASTM D1238, and an environmental stress crack resistance (ESCR) of at least 500 hours as measured in 100% Igepar solution according to ASTM D1693; the composition has a volume electrical resistivity of less than 5 ohm-centimeters (ohm-cm), measured in accordance with ASTM D991 or ASTM D257; the composition has a MFR of at least 4 g / 10 min measured at 280°C and 21.6 kg according to ASTM D1238; A method wherein the total weight percentage of all components does not exceed 100 wt%, and all weight percentages are based on the total weight of the composition.

[0062] Embodiment 11. The method of embodiment 10, wherein the polyethylene polymer comprises a copolymer comprising ethylene and hexene monomers.

[0063] Embodiment 12. The method of embodiment 10, wherein the polyethylene polymer comprises a copolymer comprising ethylene monomer and one or more monomers selected from the group consisting of 1-butene, 1-hexene, 1-octene, 1-decene, 1-octadecene, and 4-methyl-1-pentene.

[0064] Embodiment 13. The method of any one of embodiments 10 to 12, wherein the polyethylene polymer has a crystallinity of at least 50% as determined by differential scanning calorimetry (DSC).

[0065] Embodiment 14. The method of embodiment 13, wherein the polyethylene polymer has a crystallinity of 50% to 95% as determined by differential scanning calorimetry (DSC).

[0066] Embodiment 15. The method of any one of embodiments 10 to 14, wherein the graphite is synthetic graphite.

[0067] Aspect 16. The carbon powder filler has a density of at least 60 grams per square meter (m) as determined in accordance with ASTM D3037. 2 16. The method of any one of embodiments 10 to 15, having a BET surface area of ​​0.1% or less.

[0068] Embodiment 17. The method of any one of embodiments 10 to 16, wherein the composition is extruded into a sheet.

[0069] Embodiment 18. The method of embodiment 17, wherein the sheet has a thickness of 0.020 inches (in) to 0.060 inches (in).

[0070] Embodiment 19. The method of any one of embodiments 10 to 16, further comprising forming the composition into a sheet using an injection molding process, a compression molding process, an injection-compression molding process, a thermoforming process, or a combination thereof. [Example]

[0071] The following examples are presented to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices, and / or methods claimed herein are made and evaluated, and are intended to be purely illustrative and not intended to limit the disclosure. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but it is desirable to account for some errors and deviations. Unless otherwise indicated, parts are parts by weight, temperature is °C or is ambient temperature, and pressure is at or near atmospheric. Percentages referring to compositions are wt% unless otherwise indicated.

[0072] There are numerous variations and combinations of reaction conditions, e.g., component concentrations, desired solvents, solvent mixtures, temperatures, pressures, and other reaction ranges and conditions, that can be used to optimize the purity and yield of the products obtained from the described processes. Optimizing such process conditions will require only reasonable and routine experimentation.

[0073] Various compositions were formed using the components listed in Table 1: Table 1 - Raw materials [Table 1] Example 1

[0074] The compositions shown in Table 2 were extruded and tested (all amounts in this and other tables are listed in wt%): Table 2 - Composition of Example 1 [Table 2]

[0075] The composition of Example 1 was formed to evaluate the effect of graphite content on extrudability and volume resistivity. Compositions C0, C1, C2, Ex1, and Ex2 were extruded without difficulty. Compositions C3 and C4 were difficult to extrude; these compositions are likely not scalable for commercial applications. These results suggest that compositions containing graphite contents greater than 50 wt.% and total carbon contents greater than 56 wt.% will be difficult to extrude. Furthermore, blends containing as much as 50 wt.% graphite and 6 wt.% carbon black may be required to achieve a volume resistivity of 1.0 ohm-cm or less.

[0076] The injection moldability of these compositions was then investigated. Compositions C0, C1, C2, Ex1, and Ex2 were injection molded without difficulty at thicknesses of 2.5 millimeters (mm) and 2.0 millimeters at injection pressures up to 30 kilopounds per square inch (psi). However, thinner samples, such as 0.025 to 0.050 inches (0.635 to 1.27 mm), may require excessive pressures of more than 30 kpsi. Thus, in certain embodiments, it may be desirable to form thin sheets (e.g., 0.025 to 0.050 inches) from an extrusion or, in some cases, an injection-compression molding process. Example 2

[0077] Additional compositions were prepared in an attempt to improve flow while still achieving the volume resistivity of Ex2. 100-lb samples were prepared and compounded at zone temperatures of 480 to 520°F, a screw speed of 200 revolutions per minute (rpm), and a throughput of 20 lb / hr. The compositions and performance are listed in Table 3: Table 3 - Composition of Example 2 [Table 3]

[0078] Sheets were extruded to a sheet thickness of 0.025". The volume resistivities of the samples, measured in accordance with ASTM D991, were approximately 1.4 ohm.cm (Ex3), 0.75 ohm.cm (C5), and 0.76 ohm.cm (C6). Sheets C5 and C6 tended to exhibit edge cracking. Thus, the samples with higher carbon black loading (C5 and C6) had improved volume resistivity properties but worsened processability. Example 3

[0079] Composition Ex3 was tested for scalability; 500-lb batches of the resin were extruded into sheets of various thicknesses in a commercial-sized extruder. Sheets having nominal thicknesses of 0.050" and 0.037" were extruded without issue, but the formulation was found to be too viscous for commercial production of 0.025" thick sheets. Extruded sheets approximately 0.050" thick exhibited a volume electrical resistivity of less than 3 ohm-cm when observed according to ASTM D991. Example 4

[0080] Additional compositions were prepared and tested to identify blends with good processability (e.g., high melt flow rate) and low volume resistivity properties. The compositions and their properties are shown in Tables 4A and 4B: Table 4A - Composition of Example 4 [Table 4] Table 4B - Table 4A Composition Properties [Table 5]

[0081] While some compositions had desirable melt flow (>4 g / 10 min) or volume resistivity (<5 ohm-cm) properties, example compositions Ex4-Ex10 had a good combination of both melt flow and volume resistivity properties. The results can be visually observed in Figure 1. Example 5

[0082] Additional compositions were prepared and tested to identify scalable blends with good processability (e.g., high melt flow rate) and low volume resistivity properties. The compositions were prepared on a 58 mm diameter commercial size compounding extruder at barrel temperatures between 460°F (238°C) and 510°F (266°C), a screw speed of 360 rpm, and 52-56% of maximum torque. The extruder was operated at a rate of 120-140 kg / hr. The compositions and their properties are shown in Tables 5A-5C: Table 5A - Example and Comparative Compositions [Table 6] Table 5B - Table 5A Composition Properties [Table 7]

[0083] As shown in Table 5B, the three expanded materials exhibited MFRs of 10 g / 10 min or greater and volume electrical resistivities of less than 3 ohm-cm when measured on injection molded plaques according to ASTM D257. Some 750 pound (lb) samples of these resins were successfully extruded into sheets of nominal thicknesses of 0.025", 0.038", and 0.050" on commercial-sized equipment. The volume electrical resistivities of extruded sheets of the three materials were tested according to ASTM D991, and values ​​between about 2 ohm-cm and 7 ohm-cm were observed, depending on the thickness of the extruded sheet. The volume resistivity results are given in Table 5C: Table 5C - Volume resistivity of the compositions of Table 5A [Table 8]

[0084] Thicker samples had lower volume resistivity properties, however, compositions C22 and C23 may not provide ideal chemical resistance properties in certain embodiments, so composition Ex11 may be preferred. Example 6

[0085] ASTM plaques of the Ex11 composition were molded and tested for mechanical properties. The plaques were tested for tensile and flexural properties at room temperature (e.g., 23°C) and at 60°C. The average mechanical properties of the plaques are shown in Table 6: Table 6 - Mechanical properties of Ex11 composition [Table 9]

[0086] Five 4" x 5" x 1 / 8" thick injection molded plaques of the Ex11 composition were tested for volume electrical resistivity and averaged about 1 ohm.cm when tested in accordance with ASTM D991. Example 7

[0087] Additional samples were prepared to identify compositions with a good balance of flow / processability, volume resistivity, and chemical resistance properties. The compositions formed are shown in Table 7A; the conductive properties of the compositions are shown in Table 7B: Table 7A - Example Compositions [Table 10] Table 7B - Table 7A Composition Properties [Table 11]

[0088] Marlex HDPE has a crystallinity of 58.6% as determined according to DSC. Both compositions have good chemical resistance and volume resistivity and were successfully extended to produce sheets 0.025", 0.037", and 0.050" thick on a commercial size sheet extruder. However, Ex12 was more easily extruded than Ex13. The sheet containing Ex13 was weak in both directions. The mechanical properties of the Ex12 and Ex13 compositions are given in Table 7C: Table 7C - Mechanical properties of Ex12 and Ex13 [Table 12]

[0089] The results in Table 7C may explain the difference in ductility observed in sheets made using the Ex12 and Ex13 compositions on a commercial-size extruder. As Table 7C shows, the tensile elongation at yield and at break for Ex12 are approximately double those for Ex13 at both room temperature and 60°C, suggesting that better elongation behavior correlates with better ductility in the extruded sheet.

[0090] The foregoing is intended to be illustrative, not limiting. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other aspects may be used, for example, upon review by one of ordinary skill in the art. The Abstract is provided to enable the reader to quickly ascertain the nature of the technical disclosure in accordance with 37 CFR §1.72(b). It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. However, no unclaimed disclosed feature should be construed as intended as essential to any claim. Rather, inventive subject matter may lie in fewer than all features of a particular disclosed embodiment. Thus, the appended claims are incorporated into the Detailed Description as examples or aspects, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the present disclosure should preferably be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. 35 wt % to 70 wt % of at least one polyethylene polymer, the polyethylene polymer comprising a copolymer comprising ethylene and hexene monomers; 25 wt % to 55 wt % of at least one graphite filler; At least 50 grams per square meter (m) as determined in accordance with ASTM D3037 ２ 2 wt % to 15 wt % of a carbon powder filler having a BET surface area of ​​0.01 wt % to 0. ... A composition comprising: The polyethylene polymer has a viscosity of at least 0.94 grams per cubic centimeter (g / cm) as determined in accordance with ASTM D1505. ３ ), a melt flow rate (MFR) of at least 10 grams per 10 minutes (g / 10 min) as measured at 190°C and 21.6 kilograms (kg) according to ASTM D1238, and an environmental stress crack resistance (ESCR) of at least 500 hours as measured in 100% Igepal solution according to ASTM D1693; the composition has a volume electrical resistivity of less than 5 ohm-centimeters (ohm-cm), as measured in accordance with ASTM D991 or ASTM D257; the composition has an MFR of at least 4 g / 10 min measured at 280° C. and 21.6 kg according to ASTM D1238; A composition wherein the total weight percentage of all components does not exceed 100 wt %, all weight percentages being based on the total weight of said composition.

2. 10. The composition of claim 1, wherein the polyethylene polymer has a crystallinity of at least 50% as determined by differential scanning calorimetry (DSC).

3. 3. The composition of claim 2, wherein the polyethylene polymer has a crystallinity of from 50% to 95% as determined by differential scanning calorimetry (DSC).

4. 10. The composition of claim 1, wherein the graphite is synthetic graphite.

5. The carbon powder filler has a density of at least 60 grams per square meter (m ) as determined in accordance with ASTM D3037. ２ 5. The composition of claim 1, having a BET surface area of ​​0.1 wt. / g.

6. An extruded sheet comprising the composition of any one of claims 1 to 4.

7. 7. The extruded sheet of claim 6 having a thickness of 0.508 millimeters (mm) to 1.524 mm.

8. % to 70 wt. % of at least one polyethylene polymer, the polyethylene polymer comprising a copolymer comprising ethylene and hexene monomers; 25 wt. % to 55 wt. % of at least one graphite filler; and a viscosity of at least 50 grams per square meter (m) determined in accordance with ASTM D3037. ２ 2 wt % to 15 wt % of a carbon powder filler having a BET surface area of ​​1000 Wt % to 1500 Wt % of a carbon powder filler, the method comprising: combining the at least one polyethylene polymer, the at least one graphite filler, and the carbon powder filler to form a mixture; extruding the mixture to form the composition; comprising The polyethylene polymer has a viscosity of at least 0.94 grams per cubic centimeter (g / cm) as determined in accordance with ASTM D1505. ３ ), a melt flow rate (MFR) of at least 10 grams per 10 minutes (g / 10 min) as measured at 190°C and 21.6 kilograms (kg) according to ASTM D1238, and an environmental stress crack resistance (ESCR) of at least 500 hours as measured in 100% Igepar solution according to ASTM D1693; the composition has a volume electrical resistivity of less than 5 ohm-centimeters (ohm-cm), as measured in accordance with ASTM D991 or ASTM D257; the composition has an MFR of at least 4 g / 10 min measured at 280° C. and 21.6 kg according to ASTM D1238; A method wherein the total weight percentage of all components does not exceed 100 wt %, all weight percentages being based on the total weight of the composition.

9. 9. The method of claim 8, wherein the polyethylene polymer has a crystallinity of at least 50% as determined by differential scanning calorimetry (DSC).

10. 10. The method of claim 9, wherein the polyethylene polymer has a crystallinity of 50% to 95% as determined by differential scanning calorimetry (DSC).

11. The method of claim 8 wherein the graphite is synthetic graphite.

12. The carbon powder filler has a density of at least 60 grams per square meter (m ) as determined in accordance with ASTM D3037. ２ 12. The method of claim 8, wherein the sintered body has a BET surface area of ​​0.15 wt. / g.

13. 12. The method of any one of claims 8 to 11, wherein the composition is extruded into a sheet having a thickness of 0.508 mm to 1.524 mm.

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