Methods for making polymer masterbatches and formulations containing both carbon black and carbon nanotubes

Abstract

The present disclosure relates to methods for making a polymer masterbatch by melt processing a first base polymer and carbon nanotubes to form a first polymer mixture, and then melt processing the first polymer mixture and a carbon black and optionally a second base polymer to form the polymer masterbatch. A related method of making a polymer composition can further include a step of melt processing the polymer masterbatch and a bulk polymer to form the polymer composition. With these methods, surface resistivity properties can be improved over conventional compounding and masterbatch preparation techniques.

Description

[0001] METHODS FOR MAKING POLYMER MASTERBATCHES AND FORMULATIONS CONTAINING BOTH CARBON BLACK AND CARBON NANOTUBES

[0002] REFERENCE TO RELATED APPLICATION

[0003] This application is being filed on March 12. 2024. as a PCT International Patent Application and claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 489,797, filed on March 13, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0004] TECHNICAL FIELD

[0005] The present disclosure relates to polymer masterbatches and subsequent formulations containing a base polymer and both carbon black and carbon nanotube additives, and more particularly, relates to methods of making such polymer masterbatches and formulations with improved surface resistivity properties.

[0006] BACKGROUND

[0007] Carbon nanotubes can be used in combination with carbon black fillers in polymer formulations for improved electrical conductivity with a relatively small increase in weight. However, it is often difficult to uniformly disperse both carbon nanotubes and carbon black in a polymer matrix, and thus it would be beneficial to develop new methods for improved filler dispersibility. Accordingly, it is to these ends that the present invention is generally directed.

[0008] SUMMARY

[0009] In accordance with the purpose(s) of the invention, as embodied and broadly described herein, this disclosure relates to methods of making polymer masterbatches and polymer compositions that contain at least one polymer, carbon black, and carbon nanotubes.

[0010] In one aspect, a method of making a polymer masterbatch is provided, and in this aspect, the method can comprise (i) melt processing a first base polymer and carbon nanotubes to form a first polymer mixture, and (ii) melt processing the first polymer mixture and a carbon black and optionally a second base polymer to form the polymer masterbatch.

[0011] In another aspect, a method of making a polymer composition is provided, and in this aspect, the method can comprise (i) melt processing a first base polymer and carbon nanotubes to form a first polymer mixture, (ii) melt processing the first polymer mixture and a carbon black and optionally a second base polymer to form the polymer masterbatch, and (iii) melt processing the polymer masterbatch and a bulk polymer to form the polymer composition.

[0012] Additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory' only and are not restrictive of the invention, as claimed.

[0013] BRIEF DESCRIPTION OF THE FIGURE

[0014] The accompanying figure, which is incorporated in and constitutes a part of this specification, illustrates several aspects and together with the description serve to explain certain principles of the invention.

[0015] FIG. 1 illustrates four methods that can be used to prepare polymer masterbatches and polymer compositions. DESCRIPTION

[0016] The present invention can be understood more readily by reference to the following detailed description of the invention and the Examples included therein.

[0017] 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 specific synthetic methods unless otherwise specified, or to particular reagents unless otherwise specified, as such can, of course, vary . It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, example methods and materials are now described.

[0018] All publications (including ASTM methods) mentioned herein are incorporated herein by reference in their entirety to disclose and describe the methods and / or materials in connection with which the publications are cited.

[0019] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, example methods and materials are now described.

[0020] As used herein, unless specifically stated to the contrary, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a polymer” or “a carbon black” includes mixtures of two or more polymers or carbon blacks, respectively.

[0021] Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another aspect includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the 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 particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0022] As used herein, the terms “optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0023] The term “polymer masterbatch” means a mixture of a base polymer(s) and a high concentration of carbon filler (carbon black and carbon nanotubes) and other optional additives such as dispersing additives, pigments, dyes, colorants, and the like.

[0024] The term “base polymer” means the polymer into which carbon nanotubes and carbon black (and any optional additives) are mixed during the melt processing steps to form the polymer masterbatch. If both a first base polymer and a second base polymer are used, these base polymers can be the same or different.

[0025] The term “melt processing” encompasses melt mixing and melt blending and can be accomplished using any suitable melt processing technique and equipment.

[0026] Melt processing of the polymer masterbatch and a “bulk polymer” is the processing step during which the masterbatch and the bulk polymer are mixed (with optional other additives) to form the final polymer composition or formulation. The term “bulk polymer” means the polymer resin with which the masterbatch is mixed to form the final polymer formulation. The bulk polymer can be the same as or different from the base polymer(s).

[0027] Disclosed are the components to be used to prepare the compositions of the invention as well as the compositions themselves to be used within the methods disclosed herein. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds cannot be explicitly disclosed, each is specifically contemplated and described herein. For example, if a particular compound is disclosed and discussed and a number of modifications that can be made to a number of molecules including the compounds are discussed, specifically contemplated is each and every combination and permutation of the compound and the modifications that are possible unless specifically indicated to the contrar . Thus, if a class of molecules A, B, and C are disclosed as well as a class of molecules D, E, and F and an example of a combination molecule. A-D is disclosed, then even if each is not individually recited each is individually and collectively contemplated meaning combinations, A-E, A-F, B-D, B-E, B-F, C-D, C-E, and C-F are considered disclosed. Likewise, any subset or combination of these is also disclosed. Thus, for example, the sub-group of 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 of making and using the compositions of the invention. Thus, if there are a variety7of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific embodiment or combination of embodiments of the methods of the invention.

[0028] Each of the materials disclosed herein are either commercially available and / or the methods for the production thereof are known to those of skill in the art.

[0029] It is understood that the compositions prepared by7the disclosed methods have certain functions. Disclosed herein are certain structural requirements for performing the disclosed functions, and it is understood that there are a variety of structures that can perform the same function that are related to the disclosed structures, and that these structures will typically achieve the same result.

[0030] Unless indicated otherwise, parts are parts by weight, temperature is in °C or is at ambient temperature, and pressure is at or near atmospheric.

[0031] A. Methods

[0032] As briefly described above, a method of making a polymer masterbatch disclosed herein can comprise (i) melt processing a first base polymer and carbon nanotubes to form a first polymer mixture, and (ii) melt processing the first polymer mixture and a carbon black and optionally a second base polymer to form the polymer masterbatch. Another method disclosed herein is directed to a method of making a polymer composition, and this method can comprise (i) melt processing a first base polymer and carbon nanotubes to form a first polymer mixture, (ii) melt processing the first polymer mixture and a carbon black and optionally a second base polymer to form the polymer masterbatch, and (iii) melt processing the polymer masterbatch and a bulk polymer to form the polymer composition.

[0033] In both of these methods, any suitable technique and equipment can be used for each respective melt processing step. Nonetheless, melt processing in step (i), (ii), and (iii) often can be performed, independently, in a single screw extrusion system, in a twin screw extrusion system, or in a Banbury mixer. If a twin screw extrusion system (e.g.. a counter-rotating mixer or a co-rotating twin screw extrusion system) is utilized, any combination of feeding, melting, mixing, and conveying elements can be employed.

[0034] Referring to step (i), the first base polymer and the carbon nanotubes can be in any suitable form. For instance, the first base polymer can be in the form of fluff, powder, granulate, pellet, and the like, and the carbon nanotubes can be in the form of powder or granulate. Often the carbon nanotubes are present in powder form in step (i). After melt processing, the resulting first polymer mixture in step (i) can contain any suitable amount of carbon nanotubes. In one aspect, from 0.5 to 10 wt. % of the first polymer mixture can be the carbon nanotubes, while in another aspect, from 1 to 6 wt. % of the first polymer mixture can be the carbon nanotubes.

[0035] In step (ii). the first polymer mixture from step (i) is combined with the carbon black and melt processed to form the polymer masterbatch. Optionally, a second base polymer can be combined with the first polymer mixture and the carbon black, and the second base polymer can be the same as or different from the first base polymer. The first polymer mixture and the carbon black (and the second base polymer, if used) can be in any suitable form. Often the carbon black is present in powder form or beaded form in step (ii). The typical properties of the polymer masterbatch are provided hereinbelow.

[0036] If a final polymer composition is to be prepared from the polymer masterbatch, per step (iii), the polymer masterbatch and a bulk polymer are combined and melt processed to form the polymer composition. The ty pical properties of the polymer composition are provided hereinbelow;

[0037] Referring now to FIG. 1, which is a schematic that illustrates four methods that can be used to prepare polymer masterbatches and polymer compositions. Method 1 is illustrative of the inventive methods for making polymer masterbatches and polymer compositions disclosed herein. In Method 1, labeled double pass in FIG. 1, carbon nanotubes (CNT) and a polymer are melt processed (e.g., via extrusion) to form a first polymer mixture (CNT MB), which is combined (e.g., via extrusion) with carbon black (CB) and optionally another polymer to form a polymer masterbatch (CB / CNT MB). To form the final polymer composition, additional polymer is added (e.g., via extrusion) to form a representative polymer composition that contains CNT: CB: polymer in a weight ratio of 1 :9:90. In Method 2, labeled single pass powder blending in FIG. 1, CB and CNT are combined (e.g., via extrusion) in one step with a polymer to form a polymer masterbatch (CB / CNT MB), which is then combined (e.g., via extrusion) with another polymer to form a representative polymer composition that contains CNT:CB: polymer in a weight ratio of 1 :9:90.

[0038] In Methods 3 and 4, labeled masterbatch in FIG. 1, a commercially-available or a home made masterbatch containing CNT is combined (e g., via extrusion) with CB (e.g., in powder form) and a polymer (e.g., polypropylene, PP) to form a representative polymer composition that contains CNT:CB: polymer in a weight ratio of 1:9:90.

[0039] Unexpectedly, it was found that Method 1 in FIG. 1 produces polymer masterbatches and subsequent polymer compositions or formulations - containing both carbon black and carbon nanotube additives - with improved surface resistivity' properties, even though the respective amounts of carbon black, carbon nanotubes, and polymer are the same.

[0040] B. Polymer Masterbatches

[0041] In an aspect, the polymer masterbatch prepared herein comprises a base polymer (or polymers) and from 20 to 70 wt. % of the carbon black and the carbon nanotubes. More often, from 25 to 50 wt. % (e.g., 25 wt. %, 30 wt. %, 35 wt. %, 40 wt. %, 45 wt. %, or 50 wt. %) of the polymer masterbatch are the carbon black and the carbon nanotubes. The weight ratio of carbon black to carbon nanotubes in the polymer masterbatch can range from 70:30 to 99.5:0.5, and in some aspects, the weight ratio of the carbon black to the carbon nanotubes in the polymer masterbatch falls within a range from 85: 15 to 98:2. In yet another aspect, the weight ratio of the carbon black to the carbon nanotubes in the polymer masterbatch can be about 95:5.

[0042] The polymer masterbatch composition can optionally comprise a dispersing additive or other suitable additive. In one aspect, the masterbatch composition can comprise a dispersing additive in an amount ranging from 0.01 wt. % to 20 wt. %. Other optional additives that can be present in the polymer masterbatch include without limitation pigments, dyes, or other materials for imparting color to an article or coating prepared from the polymer masterbatch composition.

[0043] C. Polymer Compositions

[0044] In an aspect, the polymer compositions prepared herein comprises a bulk polymer (or polymers) and the polymer masterbatch, which can contain from 20 to 70 wt. % of the carbon black and the carbon nanotubes. While not limited thereto, from 1 to 30 wt. % of the final polymer composition are the carbon black and the carbon nanotubes. More often, from 5 to 15 wt. % (e.g., 5 wt. %, 8 wt. %. 10 wt. %, 12 wt. %, or 15 wt. %) of the polymer composition are the carbon black and the carbon nanotubes. The weight ratio of carbon black to carbon nanotubes in the polymer composition can range from 70:30 to 99.5:0.5, and in some aspects, the weight ratio of the carbon black to the carbon nanotubes in the polymer composition falls within a range from 85: 15 to 98:2. In yet another aspect, the weight ratio of the carbon black to the carbon nanotubes in the polymer composition can be about 95:5.

[0045] As would be recognized by one of skill in the art, the final polymer composition - which contains a particular loading of the polymer masterbatch - can contain a variety of additives and combinations of polymers, depending upon the end-use application of the polymer composition.

[0046] D. Base Polymers and Bulk Polymers

[0047] The methods for making a polymer masterbatch and the methods for making a polymer composition can utilize a variety of base polymers and bulk polymers. In general, any polymer that can be used as a carrier for a masterbatch composition or for the formation of a final polymer composition can be utilized. Thus, the first base polymer, the second base polymer, and the bulk polymer independently can comprise a thermoplastic polymer, a thermoset polymer, an elastomeric polymer, or a combination thereof. Specific non-limiting examples include polyolefins such as polyethylene or polypropylene (e.g., Braskem PP D115A), polyamides, polystyrenes, polyvinyl chlorides, acrylonitrile butadiene styrenes, polycarbonates, polyesters, and the like, as well as combinations thereof.

[0048] E. Carbon Black

[0049] The carbon black filler can comprise any suitable carbon black material. In one aspect, the carbon black can comprise a conductive or semi -conductive carbon black. In another aspect, the carbon black can comprise a high structure carbon black. High structure carbon black can increase compound viscosity, modulus, and conductivity. High structure can also reduce die swell, loading capacity, and improve dispersibility. Lower structure carbon blacks can decrease compound viscosity and modulus, increase elongation, die swell and loading capacity, but can also decrease dispersibility. If all other features of a carbon black are kept constant, narrow aggregate size distribution increases difficulty of carbon black dispersion and increases hysteresis and lowers resilience.

[0050] In one aspect, the carbon black has a nitrogen surface area (NSA) of from 25 to 250 m2 / g, as measured according to ASTM D6556 (2015). In a further aspect, the carbon black has a nitrogen surface area (NSA) of from 40 to 90 m2 / g, as measured according to ASTM D6556 (2015).

[0051] Additionally or alternatively, the carbon black has an oil absorption number (OAN) of from 45 to 250 cm3 / 100g. as measured according to ASTM D2414 (2019). For example, the carbon black can have an oil absorption number of 45, 50, 60, 70, 80, 90, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 200, 220, or 250 cc / lOOg, as measured according to ASTM D2414 (2019). In a further aspect, the carbon black has an oil absorption number (OAN) of from 120 to 210 cm3 / 100g, or from 120 to 170 cm3 / 100g. as measured according to ASTM D2414 (2019). In various specific aspects, the carbon black can comprise Birla Carbon 7055, 7060, 7067, CONDUCTEX 7055 ULTRA, CONDUCTEX KU, CONDUCTEX SCU, RAVEN P, RAVEN P7U, or RAVEN PFEB carbon blacks, available from Birla Carbon, Marietta, Georgia USA. Other suitable carbon blacks can be used.

[0052] The basic method for the production of carbon black is well know n. Generally, carbon black is produced by the partial oxidation or thermal decomposition of hydrocarbon gases or liquids, where a hydrocarbon raw material (hereinafter called “feedstock hydrocarbon”) is injected into a flow of hot gas wherein the feedstock hydrocarbon is pyrolyzed and converted into a smoke before being quenched by a water spray. The hot gas is produced by burning fuel in a combustion section. The hot gas flows from the combustion section into a reaction section which is in open communication with the combustion section. The feedstock hydrocarbon is introduced into the hot gas as the hot gas flows through the reaction section, thereby forming a reaction mixture comprising particles of forming carbon black. The reaction mixture flows from the reactor into a cooling section which is in open communication with the reaction section. At some location in the cooling section, one or more quench sprays of, for example, water, are introduced into the flowing reaction mixture thereby lowering the temperature of the reaction mixture below the temperature necessary for carbon black production and halting the carbon formation reaction. The black particles are then separated from the flow of hot gas. A broad range of carbon black types can be made by controlled manipulation of the reactor conditions.

[0053] F. Carbon Nanotubes

[0054] Any suitable carbon nanotubes can be used to prepare the masterbatch compositions. In one aspect, the carbon nanotubes comprise multi-walled carbon nanotubes, single-walled carbon nanotubes, or a mixture thereof. The multi-walled carbon nanotubes, when present, can vary in diameter, aspect ratio, or purity.

[0055] In some aspects, the carbon nanotubes have an average diameter of from 1.5 to

[0056] 25 nm. In a further aspect, the carbon nanotubes have an average diameter of from 9 to 15 nm. In one aspect, the carbon nanotubes have an average length of from 1 to 50 pm. In a further aspect, the carbon nanotubes have an average length of from 1.5 to 15 pm. A specific, non-limiting example of a carbon nanotube grade useful with the methods disclosed herein is NC7000, available from Nanocyl.

[0057] EXAMPLES

[0058] Various exemplary embodiments of the invention are detailed below. These embodiments are intended to be exemplary and are not intended to limit the scope of the invention.

[0059] The surface resistivity of polymer compositions prepared by polymer masterbatches was measured using a Loresta-GP (MCP-T600) or a Hiresta-UP (MCP- HT450) at 90V and 100V, respectively.

[0060] Examples 1-9 are summarized in Table 1 below. In reference to FIG. 1, Example 1 was prepared in accordance with Method 2. A high melt flow PP (PPI 105E1, 34 g / 10 min MFR) was extruded with beaded CONDUCTEX 7055 ULTRA carbon black and powder Nanocyl NC7000 (weight ratio of CB:CNT was 95:5) at 255 °C to produce a 25 wt. % carbon black additive masterbatch (total of CB and CNT). The 25 wt. % masterbatch was then melt processed with a virgin polypropylene (Braskem PP DI 15A) resin using a twin-screw extruder (16 mm, 25: 1) at 230 °C to achieve the final polymer composition that contained CNT: CB: polymer in a weight ratio of 0.5:9.5:90. Example 7 was produced similarly, but with a final polymer composition that contained CNT:CB:polymer in a weight ratio of 0.37:9.5:90.13.

[0061] Example 2 was prepared in accordance with Method 3 in FIG. 1. A 20 wt. % masterbatch of NC7000 in PP was mixed with beaded CONDUCTEX 7055 ULTRA carbon black and melt processed with a virgin polypropylene (Braskem PP DI 15A) resin using a twin-screw extruder (16 mm, 25: 1) at 230 °C to achieve the final polymer composition that contained CNT:CB:polymer in a weight ratio of 0.5:9.5:90. Example 8 and Example 9 w ere produced similarly, but with a final polymer composition that contained CNT:CB:polymer in a weight ratio of 0.75: 10:89.25 and 0.30: 15:84.7. respectively.

[0062] Example 3 was prepared in accordance with Method 1 in FIG. 1. In a first step, a PP base polymer was mixed with 2. 1 wt. % NC7000 in a twin-screw extruder at a melt temperature of 230 °C to form a first polymer mixture, which was then combined with 28.5 wt. % beaded CONDUCTEX 7055 ULTRA carbon black and melt processed in the twin-screw extruder at a melt temperature of 230 °C to form the CB / CNT masterbatch. The masterbatch was let-down in virgin polypropylene and melt processed using a twin-screw extruder at 230 °C to achieve the final polymer composition that contained CNT:CB: polymer in a weight ratio of 0.5:9.5:90. Example 4, Example 5, and Example 6 were produced similarly, but with a final polymer composition that contained CNT:CB:polymer in a weight ratio of 0.625: 11.875:87.5, 0.75: 14.25:85, and 0.75:9.25:90, respectively.

[0063] Referring now to Table 1, the final polymer compositions of Examples 1-3 were the same, but the surface resistivity varied significantly. Unexpectedly, the polymer composition of Example 3 - which w as prepared using Method 1 in FIG. 1 - had far superior surface resistivity, orders of magnitude lower than that of the polymer compositions of Examples 1 -2. Similarly, the polymer compositions of Example 5 and Example 6 - which w ere prepared using Method 1 in FIG. 1 - had far superior surface resistiv ity to the polymer composition of Example 8, which was prepared using Method 3. Even more surprising, the polymer composition of Example 4 - which was prepared using Method 1 in FIG. 1 - had far superior surface resistivity to the polymer composition of Example 8, despite containing 15-20 wt. % less carbon nanotubes.

[0064] While not wishing to be bound by theory’, it is believed that Method 1 (used in Examples 3-6) more effectively disperses the carbon nanotube and carbon black additives in the polymer matrix, thereby’ resulting in superior surface resistivity' properties, even with low er filler amounts. Table 1: Surface Resistivity of Polypropylene (PP) compositions containing carbon black (CB) and Multiwalled Carbon Nanotubes (CNT).

[0065] ASPECTS

[0066] It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. Other aspects of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims. Other aspects of the invention can include, but are not limited to, the following (aspects are described as “comprising'’ but, alternatively, can “consist essentially of or “consist of’):

[0067] Aspect 1. A method of making a polymer masterbatch, the method comprising (i) melt processing a first base polymer and carbon nanotubes to form a first polymer mixture, and (ii) melt processing the first polymer mixture and a carbon black and optionally a second base polymer to form the polymer masterbatch.

[0068] Aspect 2. A method of making a polymer composition, the method comprising (i) melt processing a first base polymer and carbon nanotubes to form a first polymer mixture, (ii) melt processing the first polymer mixture and a carbon black and optionally a second base polymer to form the polymer masterbatch, and (iii) melt processing the polymer masterbatch and a bulk polymer to form the polymer composition.

[0069] Aspect 3. The method defined in aspect 1 or 2, wherein the carbon nanotubes are multi-walled carbon nanotubes, single-walled carbon nanotubes, or a combination thereof.

[0070] Aspect 4. The method defined in any one of aspects 1-3, wherein the carbon nanotubes have an average diameter in a range from 1.5 to 25 nm.

[0071] Aspect 5. The method defined in any one of aspects 1-3, wherein the carbon nanotubes have an average diameter in a range from 9 to 15 nm.

[0072] Aspect 6. The method defined in any one of aspects 1-5, wherein the carbon nanotubes have an average length in a range from 1 to 50 pm.

[0073] Aspect 7. The method defined in any one of aspects 1-5, wherein the carbon nanotubes have an average length in a range from 1.5 to 15 pm.

[0074] Aspect 8. The method defined in any one of aspects 1 -7, wherein the first base polymer, the second base polymer, and the bulk polymer independently comprise a thermoplastic polymer, a thermoset polymer, an elastomeric polymer, or a combination thereof.

[0075] Aspect 9. The method defined in any one of aspects 1-7, wherein the first base polymer, the second base poly mer, and the bulk polymer independently comprise a polyethylene, a polypropylene, a polyamide, a pol st rene, a polyvinyl chloride, an acrylonitrile butadiene styrene, a polycarbonate, a polyester or a combination thereof. Aspect 10. The method defined in any one of aspects 1-9, wherein the melt processing in step (i), (ii), and (iii) is performed, independently, in a single screw extrusion system, a twin screw extrusion system, or a Banbury mixer.

[0076] Aspect 11. The method defined in any one of aspects 1-10, wherein the carbon nanotubes in step (i) are present as a powder.

[0077] Aspect 12. The method defined in any one of aspects 1-11, wherein the carbon black in step (ii) is present as a powder or beads.

[0078] Aspect 13. The method defined in any one of aspects 1-12, wherein a weight ratio of the carbon black to the carbon nanotubes in the polymer masterbatch, or in the polymer composition, is in a range from 70:30 to 99.5:0.5.

[0079] Aspect 14. The method defined in any one of aspects 1-12, wherein a weight ratio of the carbon black to the carbon nanotubes in the polymer masterbatch, or in the polymer composition, is in a range from 85:15 to 98:2.

[0080] Aspect 15. The method defined in any one of aspects 1-12, wherein a weight ratio of the carbon black to the carbon nanotubes in the polymer masterbatch, or in the polymer composition, is about 95:5.

[0081] Aspect 16. The method defined in any one of aspects 1-15, wherein the carbon black has a nitrogen surface area (NSA) in a range from 25 to 250 m2 / g, as measured according to ASTM D6556 (2015).

[0082] Aspect 17. The method defined in any one of aspects 1-15, wherein the carbon black has a nitrogen surface area (NSA) in a range from 40 to 90 m2 / g, as measured according to ASTM D6556 (2015). Aspect 18. The method defined in any one of aspects 1-17, wherein the carbon black has an oil absorption number (OAN) in a range from 45 to 250 cm3 / 100g, as measured according to ASTM D2414 (2019).

[0083] Aspect 19. The method defined in any one of aspects 1-17, wherein the carbon black has an oil absorption number (OAN) in a range from 120 to 210 cm3 / 100g. or from 120 to 170 cm3 / 100g, as measured according to ASTM D2414 (2019).

[0084] Aspect 20. The method defined in any one of aspects 1-19, wherein from 0.5 to 10 wt. % of the first polymer mixture are the carbon nanotubes.

[0085] Aspect 21. The method defined in any one of aspects 1-19, wherein from 1 to 6 wt. % of the first polymer mixture are the carbon nanotubes.

[0086] Aspect 22. The method defined in any one of aspects 1-21, wherein from 20 to 70 wt. % of the polymer masterbatch are the carbon black and the carbon nanotubes.

[0087] Aspect 23. The method defined in any one of aspects 1-21, wherein from 25 to 50 wt. % of the polymer masterbatch are the carbon black and the carbon nanotubes.

[0088] Aspect 24. The method defined in any one of aspects 2-23, wherein from 1 to 30 wt. % of the polymer composition are the carbon black and the carbon nanotubes.

[0089] Aspect 25. The method defined in any one of aspects 2-23, wherein from 5 to 15 wt. % of the polymer composition are the carbon black and the carbon nanotubes.

Claims

CLAIMSWhat is claimed is:

1. A method of making a polymer masterbatch, the method comprising:(i) melt processing a first base polymer and carbon nanotubes to form a first polymer mixture; and(ii) melt processing the first polymer mixture and a carbon black and optionally a second base polymer to form the polymer masterbatch.

2. A method of making a polymer composition, the method comprising:(i) melt processing a first base polymer and carbon nanotubes to form a first polymer mixture;(ii) melt processing the first polymer mixture and a carbon black and optionally a second base polymer to form the polymer masterbatch; and(iii) melt processing the polymer masterbatch and a bulk polymer to form the polymer composition.

3. The method of claim 1 or 2, wherein the carbon nanotubes are multi-walled carbon nanotubes, single-walled carbon nanotubes, or a combination thereof.

4. The method of any one of claims 1-3, wherein the carbon nanotubes have an average diameter in a range from 1.5 to 25 nm.

5. The method of any one of claims 1-3, wherein the carbon nanotubes have an average diameter in a range from 9 to 15 nm.

6. The method of any one of claims 1-5, wherein the carbon nanotubes have an average length in a range from 1 to 50 pm.

7. The method of any one of claims 1-5, wherein the carbon nanotubes have an average length in a range from 1.5 to 15 gm.

8. The method of any one of claims 1-7, wherein the first base polymer, the second base polymer, and the bulk polymer independently comprise a thermoplastic polymer, a thermoset polymer, an elastomeric polymer, or a combination thereof.

9. The method of any one of claims 1-7, wherein the first base polymer, the second base polymer, and the bulk polymer independently comprise a polyethylene, a polypropylene, a polyamide, a polystyrene, a polyvinyl chloride, an acrylonitrile butadiene styrene, a polycarbonate, a polyester or a combination thereof.

10. The method of any one of claims 1-9, wherein the melt processing in step (i), (ii), and (iii) is performed, independently, in a single screw extrusion system, a twin screw extrusion system, or a Banbury mixer.

11. The method of any one of claims 1-10, wherein the carbon nanotubes in step (i) are present as a powder.

12. The method of any one of claims 1-11, wherein the carbon black in step (ii) is present as a powder or beads.

13. The method of any one of claims 1-12, wherein the carbon black has a nitrogen surface area (NSA) in a range from 25 to 250 m2 / g, as measured according to ASTM D6556 (2015).

14. The method of any one of claims 1-12, wherein the carbon black has a nitrogen surface area (NSA) in a range from 40 to 90 m2 / g, as measured according to ASTM D6556 (2015).

15. The method of any one of claims 1-14, wherein the carbon black has an oil absorption number (OAN) in a range from 45 to 250 cm3 / 100g. as measured according to ASTM D2414 (2019).

16. The method of any one of claims 1-14, wherein the carbon black has an oil absorption number (OAN) in a range from 120 to 210 cm3 / 100g, or from 120 to 170 cm3 / ! 00g, as measured according to ASTM D2414 (2019).

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