Solid carbon black materials and their preparation and compositions and articles containing the same

Abstract

Solid carbon black materials are provided that are particularly useful for obtaining rubber compounds with low hysteresis, for example, for the manufacture of energy-saving tires with enhanced cure rates compared to the use of conventional oxidized carbon blacks.SOLUTION: A solid carbon black material is provided that comprises an oxidized carbon black having a pH greater than 7 as measured according to ASTMD1512-15b Test Methods B - Sonic Slurry. Also provided are compositions comprising such solid carbon black materials and a polymer component, and articles made therefrom. The present disclosure also provides a method of making the solid carbon black material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to solid carbon black materials comprising oxidized carbon black, more specifically basic oxidized carbon black, related polymer compositions, particularly vulcanizable rubber compositions, and articles made therefrom, as well as methods for preparing each. The solid carbon black materials are particularly useful for obtaining rubber products, such as tire applications, with improved cure rates and reduced hysteresis compared to the use of conventional oxidized carbon black. [Background technology]

[0002] Polymer compositions, such as rubber compositions, are widely used to manufacture numerous industrial products, such as transmission and conveyor belts, tires, or footwear. Carbon black is included in many polymer compositions to modify their color, mechanical, electrical, and / or processing properties. For example, carbon black is commonly added to rubber compositions used to manufacture tires or their components to impart electrical dissipative properties to the insulating matrix. At the same time, carbon black additives affect mechanical and elastic properties such as stiffness, abrasion resistance, and hysteresis, which greatly affect the performance of the resulting tire, for example, with respect to its rolling resistance and durability. Here, carbon black tends to form networks in the matrix through strong filler-filler interactions, which are the primary source of heat accumulation in the rubber component. Due to increasing regulatory requirements and environmental pressures, there is an increasing demand for energy-efficient tires with low rolling resistance. At the same time, other performance parameters, such as grip, traction, and durability, must not be adversely affected. This often represents a competing requirement.

[0003] One option for reducing the energy lost in the form of heat during deformation of a rubber material, reflected by a lower hysteresis, is to reduce filler-filler interactions by increasing the interaction between the carbon black filler and the rubber matrix. Hysteresis can also be reduced by decreasing the carbon black loading and / or increasing the carbon black particle size. However, this may simultaneously degrade mechanical properties such as electrical dissipation and / or abrasion resistance, puncture resistance, or chip resistance.

[0004] Alternatively, chemical modifications of the rubber material and / or carbon black filler have been developed to enhance filler-rubber interactions.

[0005] For example, U.S. Patent No. 5,248,722 describes an elastomer composition that utilizes an end-functionalized polymer in combination with an acid-functional oxidized carbon black to reduce rolling resistance in tire tread applications. However, the end-functionalized polymer is not readily available and must be prepared in a dedicated process by reacting a polymer prepared by polymerization of at least one diene monomer and, optionally, one or more vinyl-substituted aromatic monomers with a tin- or nitrogen-containing compound.

[0006] According to WO 2011 / 028337, the use of surface-treated carbon black in combination with functionalized SBR polymers functionalized with oxygen-containing groups, such as carboxylic acid or hydroxyl groups, along the chain enhances carbon black-elastomer interactions, resulting in reduced hysteresis and wet traction benefits compared to the use of conventional carbon black-containing compounds. Surface treatment of the carbon black can involve oxidation of the carbon black followed by treatment with a base, such as an amine. The surface-treated carbon black is still acidic, exhibiting a pH of <7.

[0007] While the use of acid-functional oxidized carbon black improves certain physicochemical properties of polymer compositions, it has been found to significantly inhibit and slow curing compared to non-oxidized carbon black, necessitating either substantially longer cure times to achieve adequate mechanical properties or the use of relatively large amounts of accelerators to achieve reasonable cure times and adequate mechanical properties. Both options increase costs. Furthermore, many accelerators raise environmental and / or toxicological concerns. For example, N,N-diphenylguanidine (DPG), commonly used as an accelerator in curable rubber compositions, is currently classified as potentially toxic to reproduction under the European REACH regulation. Therefore, the use of such substances should be minimized or avoided, if possible.

[0008] It would therefore be desirable to provide a carbon black-based additive that improves the relevant properties of a polymer composition, such as a rubber composition that exhibits improved hysteresis for the manufacture of tires with low rolling resistance, without adversely affecting the cure characteristics of the polymer composition or requiring the need for expensive and potentially harmful auxiliary materials. The carbon black-based additive should further be provided in a form that is convenient for processing and handling.

[0009] It is therefore an object of the present invention to provide a carbon black-based material capable of imparting the aforementioned properties to polymer compositions, such as rubber compounds, while mitigating or avoiding the drawbacks of the prior art. The provision of a carbon black-based material should be achievable in an efficient and economical manner, utilizing readily available components and processing techniques. A particular object of the present invention is to provide a vulcanizable rubber composition that provides improved hysteresis suitable for tire manufacturing, without the reduced cure properties or the need for potentially harmful cure accelerators found in conventional oxidized carbon black additives. Summary of the Invention

[0010] It has now surprisingly been found that the above object can be achieved by a solid carbon black material comprising an oxidized carbon black having a pH greater than 7, as specified in the accompanying independent claim 1. Particular or preferred variants of the solid carbon black material of the invention are set out in the dependent claims.

[0011] The solid carbon black material of the present invention can be obtained by a process comprising: (i) providing oxidized carbon black; (ii) treating the oxidized carbon black with a base, preferably an aqueous alkali metal hydroxide solution; (iii) optionally, wet-beading the oxidized carbon black.

[0012] The present invention also relates to a composition comprising a polymer component and the solid carbon black material according to the present invention, and to articles prepared from such a composition. The composition may in particular be a vulcanizable rubber composition.

[0013] The solid carbon black material according to the present invention can be obtained from commercially available ingredients in a cost-effective and efficient manner using common processing techniques. Unlike liquid systems, such as dispersions, it is convenient to process and handle without potentially disturbing or diluting the carrier medium. It has been found that the solid carbon black material according to the present invention imparts favorable physical properties to polymer compositions, particularly rubber compositions, resulting in significantly reduced hysteresis without affecting cure characteristics, making it particularly interesting for the production of energy-efficient tires. Indeed, it has been found that curable polymer compositions containing the solid carbon black material according to the present invention can be cured as quickly as corresponding compositions containing unoxidized carbon black, without the need for additional cure accelerators. The solid carbon black material therefore makes it possible to minimize or avoid the use of potentially harmful cure accelerators, such as DPG.

[0014] These and other optional features and advantages of the present invention are described in more detail in the following description. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 illustrates cure by plotting measured torque versus time, comparing corresponding rubber compositions with non-oxidized carbon black (Example 1) and conventional acidic oxidized carbon black (Example 2) with a rubber composition containing a solid carbon black material according to the present invention (Example 3), each with different concentrations of cure accelerator. DETAILED DESCRIPTION OF THE INVENTION

[0016] As used herein, the term "comprising" is understood to be open-ended and not to exclude the presence of additional, undescribed or unlisted elements, materials, components, or method steps. The terms "including," "containing," and similar terms are understood to be synonymous with "comprising." As used herein, the term "consisting of" is understood to exclude the presence of any unspecified elements, components, or method steps.

[0017] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0018] Unless otherwise noted, the numerical parameters and ranges set forth in the following specification and appended claims are approximations. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. Any numerical values, however, contain errors necessarily resulting from the standard deviation in their respective measurements.

[0019] It should also be understood that any numerical range recited herein is intended to encompass all subranges therein. For example, a range of "1 to 10" is intended to encompass any and all subranges between and including the recited minimum value of 1 and the recited maximum value of 10, i.e., all subranges beginning with a minimum value of 1 or greater and ending with a maximum value of 10 or less, for example, all subranges between 1 to 6.3, or 5.5 to 10, or 2.7 to 6.1.

[0020] As stated above, the present invention relates to a solid carbon black material comprising an oxidized carbon black having a pH greater than 7.

[0021] As used herein, "carbon black material" refers to a material based on one or more carbon blacks. Thus, a carbon black material typically comprises at least 50% by weight, e.g., at least 70% by weight, at least 80% by weight, typically at least 90% by weight, at least 95% by weight, at least 98% by weight, at least 99% by weight, at least 99.5% by weight, or at least 99.9% by weight of one or more carbon blacks, based on the total solids weight of the material. Thus, a carbon black material can consist essentially of carbon black. The term "consisting essentially of" as used herein means that even if a material contains substances other than those listed, they are present only as intentionally unadded impurities, typically in amounts so small that they do not significantly affect the properties of the material. For example, the amount of such non-listed substances other than carbon black in a material can be 0.1% by weight or less. A carbon black material can, for example, consist of carbon black, i.e., 100% by weight of one or more carbon blacks.

[0022] As referred to herein, "carbon black" refers to a material that substantially comprises, for example, more than 80%, 90%, or even 95% by weight of carbon produced by controlled partial pyrolysis of one or more hydrocarbon precursors, based on its total weight. Various industrial methods for producing carbon black are known, such as the furnace process, the gas black process, the acetylene black process, the thermal black process, or the lamp black process. Carbon black production is well known in the art and is reviewed, for example, in J.-B. Donnet et al., "Carbon Black: Science and Technology," 2nd Edition, and therefore will not be described in further detail here. The carbon black material used in the practice of the present invention can comprise a single type of carbon black or a mixture of two or more different carbon black grades.

[0023] As mentioned above, the solid carbon black material according to the present invention comprises oxidized carbon black. The term "oxidized carbon black," as used herein, refers to carbon black that has been subjected to an oxidative treatment and therefore contains oxygen-containing functional groups. Thus, oxidized carbon black, unlike non-oxidized carbon black, generally has a significant oxygen content and contains oxygen-containing functional groups, examples of which include, but are not limited to, quinone, carboxyl, phenol, lactol, lactone, anhydride, and ketone groups.

[0024] Oxidized carbon black can be produced by various methods known in the art, such as those disclosed in U.S. Patent Nos. 6,120,594 and 6,471,933. Suitable methods include, for example, oxidation of carbon black materials with peroxides such as hydrogen peroxide, persulfates such as sodium persulfate and potassium persulfate, hypohalites such as sodium hypochlorite, ozone gas or oxygen gas, permanganates, transition metal-containing oxidizing agents such as osmium tetroxide, chromium oxide, ammonium cerium nitrate, or oxidizing acids such as nitric acid and perchloric acid, and mixtures or combinations thereof. Conventional oxidized carbon blacks have acid functionality and typically exhibit a pH in the range of 2 to 6.

[0025] The oxidized carbon black used in the solid carbon black material of the present invention, on the other hand, has base functionality rather than acid functionality. In other words, the oxidized carbon black of the present invention has a pH greater than 7. For example, the oxidized carbon black of the present invention can have a pH of 7.1 or greater, e.g., 7.2 or greater, 7.5 or greater, 7.8 or greater, 8.0 or greater, 8.5 or greater, 9.0 or greater, 9.5 or greater, or 10.0 or greater. For example, the oxidized carbon black of the present invention can have a pH of 12.0 or less, e.g., 11.5 or less, 11.0 or less, 10.5 or less, 10.0 or less, 9.5 or less, 9.0 or less, or 8.5 or less. The oxidized carbon black can have a pH in any range between the above lower and upper limits. For example, the oxidized carbon black of the present invention can have a pH in the range of 7.1 to 12.0, e.g., 7.2 to 10.5, 7.5 to 9.5, or 8.0 to 9.0. The pH of the oxidized carbon black is measured according to ASTM D1512-15b Test Method B - Sonic Slurry.

[0026] The degree of oxidation of the oxidized carbon black used in the practice of the present invention can vary. For example, the oxidized carbon black can have an oxygen content of 0.5% by weight or more, e.g., 1.0% by weight or more, 2.0% by weight or more, 3.0% by weight or more, 4.0% by weight or more, 5.0% by weight or more, 7.5% by weight or more, or 10.0% by weight or more, based on the total weight of the oxidized carbon black. Typically, the oxygen content of the oxidized carbon black does not exceed 20% by weight, based on the total weight of the oxidized carbon black material. For example, the oxidized carbon black can have an oxygen content of 20% by weight or less, e.g., 15% by weight or less, 10% by weight or less, 8.0% by weight or less, 7.0% by weight or less, 6.0% by weight or less, 5.0% by weight or less, or 4.0% by weight or less, based on the total weight of the oxidized carbon black. The oxidized carbon black of the present invention can have an oxygen content ranging between any of the above lower and upper limits. For example, the oxidized carbon black can have an oxygen content ranging from 0.5% to 20.0%, 1.0% to 15.0%, 2.0% to 10.0%, or 2.0% to 5.0% by weight, based on the total weight of the oxidized carbon black material. The oxygen content can be determined by elemental analysis, as described in more detail in the Examples.

[0027] The oxidized carbon black of the present invention can be further characterized by its volatile content. The volatile content values ​​described herein are measured by thermogravimetry at a temperature of 950°C, as described in detail in the Examples. For example, the oxidized carbon black can have a volatile content of 1.0 wt% or more, e.g., 1.5 wt% or more, 2.0 wt% or more, 2.5 wt% or more, 3.0 wt% or more, 3.5 wt% or more, 4.0 wt% or more, 5.0 wt% or more, 7.5 wt% or more, or 10.0 wt% or more, based on the total weight of the oxidized carbon black. For example, the oxidized carbon black can have a volatile content of 20.0 wt% or less, e.g., 15.0 wt% or less, 10.0 wt% or less, 8.0 wt% or less, 7.0 wt% or less, 6.0 wt% or less, or 5.0 wt% or less, based on the total weight of the oxidized carbon black. The oxidized carbon black of the present invention can have a volatile content ranging between any of the above lower and upper limits. For example, the oxidized carbon black can have a volatile content in the range of 1.0 wt. % to 20 wt. %, 1.0 wt. % to 15.0 wt. %, 2.0 wt. % to 10.0 wt. %, or 3.0 wt. % to 5.0 wt. %, based on the total weight of the oxidized carbon black material.

[0028] The oxidized carbon black used in the present invention can be further characterized by BET surface area, statistical thickness surface area (STSA), oil absorption (OAN), pressed oil absorption (COAN), or iodine adsorption (more specifically described below), or any combination thereof.

[0029] The oxidized carbon black according to the present invention is, for example, 50 ml 2 / g or more, e.g., 60m 2 / g or more, 70m 2 / g or more, 75m 2 / g or more, 80m 2 / g or more, 85m 2 / g or more, 90m 2 / g or more, or 95m 2 The oxidized carbon black can have a BET surface area of ​​500 m / g or more. 2 / g or less, e.g., 400m 2 / g or less, 300m 2 / g or less, 250m 2 / g or less, 200m 2 / g or less, 150m 2 / g or less, 130m 2 / g or less, 120m 2 / g or less, 110m 2 / g or less, or 100m 2 The oxidized carbon black of the present invention may have a BET surface area of ​​50 to 500 m / g or less. The oxidized carbon black of the present invention may have a BET surface area ranging between any of the above lower and upper limits. For example, the BET surface area of ​​the oxidized carbon black of the present invention may be 50 to 500 m / g. 2 / g, e.g., 70 to 300 m 2 / g, typically 75-250m 2 / g, e.g., 80-200m 2 / g, or 90-150m 2 The BET surface area can be measured according to ASTM D6556-17.

[0030] The oxidized carbon black used in accordance with the present invention is 30m 2 / g or more, e.g., 40m 2 / g or more, 50m 2 / g or more, 60m 2 / g or more, 70m 2 / g or more, 75m 2 / g or more, 80m 2 / g or more, or 85m 2 Oxidized carbon black can have a statistical thickness surface area (STSA) of 500 m / g or more. 2 / g or less, e.g., 400m 2 / g or less, 300m 2 / g or less, 250m 2 / g or less, 200m 2 / g or less, 150m 2 / g or less, 130m 2 / g or less, 120m 2 / g or less, 110m 2 / g or less, or 100m 2The oxidized carbon black of the present invention may have an STSA of 30 to 500 m / g or less. The oxidized carbon black of the present invention may have an STSA between any of the above lower and upper limits. For example, the oxidized carbon black of the present invention may have an STSA of 30 to 500 m / g or less. 2 / g, e.g., 50 to 400 m 2 / g, 60-300m 2 / g, 70-200m 2 / g, 80-150m 2 / g, or 85-120m 2 The statistical thickness surface area (STSA) can be measured according to ASTM D6556-17.

[0031] The oxidized carbon black used in the present invention can have an oil absorption number (OAN) measured in accordance with ASTM D2414-18 of 50 mL / 100 g or more, e.g., 60 mL / 100 g or more, 70 mL / 100 g or more, 80 mL / 100 g or more, 90 mL / 100 g or more, or 100 mL / 100 g or more. For example, the oxidized carbon black can have an oil absorption number (OAN) measured in accordance with ASTM D2414-18 of 150 mL / 100 g or less, e.g., 140 mL / 100 g or less, 130 mL / 100 g or less, 120 mL / 100 g or less, or 110 mL / 100 g or less. The oxidized carbon black used in the present invention can have an oil absorption number (OAN) measured in accordance with ASTM D2414-18 between any of the above lower and upper limits. For example, the oxidized carbon black of the present invention can have an oil absorption number (OAN), measured according to ASTM D2414-18, in the range of 50 to 150 mL / 100 g, e.g., 60 to 140 mL / 100 g, 70 to 130 mL / 100 g, 80 to 120 mL / 100 g, or 90 to 110 mL / 100 g.

[0032] The oxidized carbon black of the present invention may further have a compressed oil absorption (COAN) of 50 mL / 100 g or more, e.g., 60 mL / 100 g or more, 70 mL / 100 g or more, 80 mL / 100 g or more, 90 mL / 100 g or more, or 95 mL / 100 g or more. The oxidized carbon black of the present invention may have a compressed oil absorption (COAN) of 150 mL / 100 g or less, e.g., 140 mL / 100 g or less, 130 mL / 100 g or less, 120 mL / 100 g or less, 110 mL / 100 g or less, or 100 mL / 100 g or less. The oxidized carbon black of the present invention may have a compressed oil absorption (COAN) ranging between any of the above lower and upper limits. For example, the oxidized carbon black of the present invention can have a compressed oil absorption (COAN) in the range of 50 to 150 mL / 100 g, e.g., 60 to 140 mL / 100 g, 70 to 130 mL / 100 g, 80 to 120 mL / 100 g, or 90 to 100 mL / 100 g. COAN can be measured according to ASTM D3493-18.

[0033] The oxidized carbon black of the present invention may further have an iodine adsorption, as measured in accordance with ASTM D1510-19, of 20 mg / g or more, e.g., 30 mg / g or more, 40 mg / g or more, 50 mg / g or more, 55 mg / g or more, or 60 mg / g or more. The oxidized carbon black of the present invention may, for example, have an iodine adsorption, as measured in accordance with ASTM D1510-19, of 300 mg / g or less, e.g., 250 mg / g or less, 200 mg / g or less, 150 mg / g or less, 120 mg / g or less, 100 mg / g or less, 90 mg / g or less, 80 mg / g or less, or 70 mg / g or less. The oxidized carbon black of the present invention may have an iodine adsorption, as measured in accordance with ASTM D1510-19, between any of the above lower and upper limits. For example, the oxidized carbon black of the present invention can have an iodine adsorption, measured according to ASTM D1510-19, in the range of 20 to 300 mg / g, e.g., 30 to 200 mg / g, 40 to 120 mg / g, or 50 to 80 mg / g.

[0034] The oxidized carbon black according to the method of the present invention can be obtained by treating the initial oxidized carbon black with a base.

[0035] The initial oxidized carbon black can be produced by any method known in the art for preparing oxidized carbon black, such as those described above. The precursor carbon black can be oxidized using an oxidizing agent, such as peroxides (e.g., hydrogen peroxide), persulfates (e.g., sodium persulfate and potassium persulfate), hypohalites (e.g., sodium hypochlorite), ozone gas or oxygen gas, permanganates, transition metal-containing oxidizing agents (e.g., osmium tetroxide, chromium oxide, ammonium cerium nitrate), or oxidizing acids (e.g., nitric acid and perchloric acid), as well as mixtures or combinations thereof. For example, the oxidized carbon black can be ozone-oxidized carbon black. The precursor carbon black subjected to oxidation can be any type of carbon black, including, but not limited to, furnace black, lamp black, gas black, or a combination thereof. Such carbon blacks are commercially available from various manufacturers, such as Orion Engineered Carbons. Thus, the oxidized carbon black can include, but is not limited to, oxidized furnace black, oxidized lamp black, oxidized gas black, or a combination thereof. Preferably, the oxidized carbon black comprises oxidized furnace black.

[0036] The initial oxidized carbon black thus prepared is generally acidic, typically exhibiting a pH in the range of 2 to 6. For example, the initial oxidized carbon black to be treated with a base can contain 20 μmol or more of carboxylic acid groups per gram of carbon black, e.g., 50 μmol or more, 100 μmol or more, 150 μmol or more, 200 μmol or more, or 300 μmol or more. For example, the initial oxidized carbon black to be treated with a base can contain 500 μmol or less of carboxylic acid groups per gram of carbon black, e.g., 400 μmol or less, 350 μmol or less, 300 μmol or less, 250 μmol or less, or 200 μmol or less. The initial oxidized carbon black to be treated with a base can contain carboxylic acid groups in a range between any of the above lower and upper limits. For example, the oxidized carbon black of the present invention can contain 50 to 500 μmol of carboxylic acid groups, or 100 to 300 μmol of carboxylic acid groups per gram of carbon black. The amount of carboxylic acid groups can be measured with high precision by the titration method described in J. Ackerman and A. Krueger, "Highly sensitive and reproducible quantification of oxygenated surface groups on carbon nanomaterials," Carbon 163 (2020), 56-62.

[0037] The acid-functional oxidized carbon black is then treated with a base to form an oxidized carbon black according to the present invention having a pH greater than 7. In principle, any known base can be used for this treatment. Suitable bases include, but are not limited to, metal oxides, metal hydroxides, metal carbonates, and other basic metal salts, ammonia, and amines, typically used as aqueous solutions. Bases that can be preferably used according to the present invention include, for example, aqueous solutions of alkali metal hydroxides or alkaline earth metal hydroxides, such as sodium hydroxide, potassium hydroxide, or calcium hydroxide. A single base or a mixture of two or more different bases can be used. The base is typically used in an approximately equimolar amount or a moderate excess relative to the acid groups in the oxidized carbon black. For example, the amount of base used can be such that the ratio of equivalents of base to acid groups in the initial oxidized carbon black to be treated is 0.8:1 or greater, e.g., 0.9:1 or greater, 1:1 or greater, 1.1:1 or greater, 1.2:1 or greater, or 1.5:1 or greater. The amount of base used can be such that the ratio of equivalents of base to acidic groups in the initial oxidized carbon black to be treated is 2:1 or less, e.g., 1.8:1 or less, or 1.5:1 or less, or 1.3:1 or less, or 1.2:1 or less, or 1.1:1 or less. This equivalent ratio can be within any one of the above lower and upper limits. For example, the ratio of equivalents of base to acidic groups in the initial oxidized carbon black to be treated can be in the range of 0.8:1 to 2:1, e.g., 0.9:1 to 1.5:1, or 0.9:1 to 1.2:1, or 1:1 to 1.1:1. Treatment with base can include thoroughly mixing the base with the oxidized carbon black. Mixing can be carried out using conventional mixing equipment, typically for a period of up to 10 minutes. However, other forms of treatment, such as applying the base to the oxidized carbon black by spraying, can be used as well.

[0038] Treatment with base can convert at least a portion of the acid functional groups of the initial oxidized carbon black to their neutralized form. Therefore, the oxidized carbon black of the present invention can contain salt groups. For example, the oxidized carbon black of the present invention can contain carboxylate groups, such as alkali metal carboxylates or ammonium carboxylates. The oxidized carbon black of the present invention can contain, for example, 20 μmol or more, 50 μmol or more, 100 μmol or more, 150 μmol or more, 200 μmol or more, or 300 μmol or more of carboxylate groups per gram of carbon black. The oxidized carbon black of the present invention can contain, for example, 500 μmol or less, e.g., 400 μmol or less, 350 μmol or less, 300 μmol or less, 250 μmol or less, or 200 μmol or less of carboxylate groups per gram of carbon black. The oxidized carbon black of the present invention can contain an amount of carboxylate groups between any of the above lower and upper limits. For example, the oxidized carbon black of the present invention may contain 50 to 500 μmol of carboxylate groups per gram of carbon black, or 100 to 300 μmol of carboxylate groups per gram of carbon black. The amount of carboxylate groups can be determined as the difference between the amount of carboxylic acid groups measured before and after the base treatment.

[0039] The acid functional groups of the initial oxidized carbon black may be mostly or completely neutralized by base treatment. For example, the acid functional groups may be neutralized to a degree of at least 80%, e.g., at least 90%, at least 95%, at least 99%, at least 99.5%, at least 99.9%, or 100%. Oxidized carbon black having a pH greater than 7 may contain, for example, less than 20 μmol / g, less than 10 μmol / g, or less than 5 μmol / g of carboxylic acid groups, and may be substantially free of carboxylic acid groups. "Substantially free of carboxylic acid groups" means that the amount of carboxylic acid groups is not measurable or does not measurably affect the properties of the oxidized carbon black.

[0040] The oxidized carbon black of the present invention can be further characterized by its aggregate size distribution (ASD). The aggregate size distribution can be measured by light scattering using a Brookhaven BI-DCP disc centrifuge, as described in U.S. Patent Application Publication No. 2019 / 0062522 A1. The oxidized carbon black of the present invention has, for example, a mode diameter D of at least 10 nm, e.g., at least 20 nm, at least 30 nm, at least 40 nm, at least 50 nm, at least 60 nm, or at least 70 nm. modeThe oxidized carbon black according to the present invention can have a mode (also called a "mode"). For example, it can have a mode of 500 nm or less, e.g., 300 nm or less, 250 nm or less, 200 nm or less, 150 nm or less, or 100 nm or less. The oxidized carbon black according to the present invention can have a mode in a range between any of the above lower and upper limits. For example, it can have a mode in the range of 10 nm to 500 nm, 30 nm to 200 nm, or 50 nm to 100 nm. The width of the particle size distribution can be expressed by its full width at half maximum (FWHM), also called ΔD50. According to DIN ISO 15825, ΔD50 represents the width of the distribution measured at the half-maximum point of the mode. The aggregate size distribution of the oxidized carbon black according to the present invention can have a ΔD50 of, for example, at least 10 nm, e.g., at least 20 nm, at least 30 nm, at least 40 nm, at least 50 nm, or at least 60 nm. For example, it can have a ΔD50 of 300 nm or less, e.g., 250 nm or less, 200 nm or less, 150 nm or less, 100 nm or less, or 80 nm or less. The oxidized carbon black of the present invention can have a ΔD50 in a range between any of the above lower and upper limits. For example, it can have a ΔD50 in the range of 10 nm to 300 nm, e.g., 30 nm to 150 nm, or 50 nm to 80 nm. The aggregate particle size distribution of the oxidized carbon black of the present invention will, to a large extent, correspond to one of the selected precursor carbon blacks from which the oxidized carbon black is prepared, and can be adjusted accordingly, as desired or necessary.

[0041] The carbon black material, including the oxidized carbon black according to the present invention, is in a solid form. For example, the solid carbon black material may be in the form of a powder. Alternatively, the solid carbon black material may be in the form of beads or pellets. Therefore, as will be understood by those skilled in the art, solid carbon black materials are distinguished from carbon black materials provided in other (non-solid) forms, such as liquid dispersions. The beads or pellets can be formed by wet or dry pelletizing the respective powdered starting material. In such cases, forming the solid carbon black material generally further comprises pelletizing the oxidized carbon black, which can be carried out simultaneously with or after the above-mentioned base treatment. Preferably, wet pelletization is used according to the present invention, in which a base can be used as a wet beading medium, which can optionally contain an organic binder and / or one or more pelleting agents as auxiliary components. The pelletization of powdered oxidized carbon black can be carried out using common pelletizing equipment, such as an agitation granulation system like a ring-bed mixer granulator, in a one-step wet pelletizing process similar to that described in EP 2913368 A1. The resulting pellets can be further dried after the pelletizing step, for example, in a rotary drum dryer. Drying can be carried out at a temperature ranging from 100°C to 250°C, for example, from 110°C to 180°C or from 120°C to 160°C. The drying time can be appropriately selected to achieve the desired dryness, for example, a residual moisture content of less than 1%. The properties of the pellets can be controlled by adjusting the parameters of the pelletizing process. For example, for a constant weight ratio of wet bead medium to powder, an increased rotation speed of the granulator generally results in smaller pellets, while an increase in the weight ratio of wet bead medium to powder favors the formation of larger pellets. The as-prepared pelletized carbon black material according to the present invention can be characterized by its pellet size distribution, which can be measured according to ASTM D1511-10. The proportion of undesirable fines can be particularly low in the pelletized carbon black material according to the present invention.Therefore, it may contain less than 1% by weight, less than 0.5% by weight, or less than 0.3% by weight of pellets having a size less than 0.125 mm, based on the total weight of the pelletized carbon black material. The proportion of pellets having a pellet size less than 0.5 mm may be 15% by weight or less, for example, 10% by weight or less, 5% by weight or less, or 2% by weight or less, based on the total weight of the pelletized carbon black material. The amount of pellets having a size in the intermediate range of 1.0 mm to 2.0 mm, which is considered desirable in terms of processing characteristics, may be 30% by weight or more, for example, 40% by weight or more, or 50% by weight or more, based on the total weight of the pelletized carbon black material. The prepared pelletized carbon black material may, if necessary, be further size-fractionated using standard methods such as sieve classification to obtain material of an appropriate pellet size.

[0042] The solid carbon black material may contain any amount of oxidized carbon black having a pH greater than 7. The solid carbon black material may contain, for example, at least 10% by weight, at least 30% by weight, at least 50% by weight, at least 80% by weight, at least 90% by weight, at least 95% by weight, or at least 99% by weight, based on the total weight of the solid carbon black material. The solid carbon black material may contain oxidized carbon black having a pH greater than 7 in an amount of 100% by weight or less, for example, 99.5% by weight or less, 99.0% by weight or less, 95% by weight or less, 90% by weight or less, 80% by weight or less, 70% by weight or less, or 50% by weight or less. The solid carbon black material may contain oxidized carbon black having a pH greater than 7 in an amount between the above lower and upper limits, for example, in an amount ranging from 10 to 100% by weight, or from 50 to 99% by weight. Preferably, the solid carbon black material consists of oxidized carbon black having a pH greater than 7.

[0043] The solid carbon black material may optionally contain one or more other carbon blacks in addition to the oxidized carbon black having a pH greater than 7 described above. Such other carbon blacks are not particularly limited and may include any conventional non-oxidized or oxidized carbon black, such as conventional acid-functional oxidized carbon blacks and / or ASTM grade carbon blacks selected from the N100 to N900 series of classifications according to ASTM D1765. When such other carbon blacks are used, the solid carbon black material typically contains less than 50% by weight, e.g., 30% by weight or less, 20% by weight or less, 10% by weight or less, 5% by weight or less, 1% by weight or less, or 0.5% by weight or less, based on the total weight of the solid carbon black material. Preferably, the solid carbon black material does not contain any carbon black other than the oxidized carbon black having a pH greater than 7.

[0044] The solid carbon black material may optionally contain components other than carbon black. Accordingly, the solid carbon black material may contain one or more auxiliary substances or processing aids conventionally used in the art of compounding such materials, such as flow additives, rheology modifiers, pelletizers, or fillers. When used, such optional auxiliary substances are used in effective amounts generally used in the art to achieve their intended functionality. Typically, the solid carbon black material according to the present invention may contain optional components other than carbon black, if used, in an amount totaling no more than 20% by weight, e.g., no more than 10% by weight, no more than 5% by weight, no more than 1% by weight, or no more than 0.5% by weight, based on the total weight of the solid carbon black material. Preferably, the solid carbon black material does not contain any such optional components other than carbon black.

[0045] As mentioned above, the present invention also relates to a composition comprising the solid carbon black material of the present invention and a polymer component. In other words, the present invention also relates to the use of the solid carbon black material in a polymer composition.

[0046] The term "composition," as used herein, refers to a material composed of multiple constituent chemical species or components. The term "polymer composition" refers to a composition containing at least one polymer component. Thus, a "polymer composition" can contain, as the polymer component, a single type of polymer material or two or more types of different polymer materials. A "polymer material" is understood as a material consisting essentially of polymers. The term "polymer" is used herein in its general sense in the art to refer to a macromolecular compound, i.e., a compound having a relatively high molecular weight (e.g., 500 da or more), the structure of which actually or conceptually comprises multiple repeating units (also called "mers") derived from relatively low molecular weight chemical species.

[0047] The composition according to the present invention may be, in particular, a curable composition, such as a vulcanizable rubber composition. The term "vulcanizable rubber composition" refers to a composition of rubber components, optionally including various additional components conventionally used in the art of rubber compounding, that can be cured by vulcanization to form a vulcanizate. The terms "curable" and "vulcanizable" are used interchangeably throughout this specification unless otherwise specified and refer to a chemical reaction that links polymer chains together with a crosslinking or vulcanizing agent. The curing reaction can be induced by any means known in the art, such as the addition of light, moisture, heat, and / or a crosslinking agent.

[0048] However, the polymeric materials that can be used in the polymer component of the composition of the present invention are not limited and can include any type of organic or inorganic polymeric material. Polymeric materials that can be used in accordance with the present invention include thermoplastic, duroplastic, or thermosetting polymers, as well as mixtures or combinations thereof. For example, polymeric materials that can be used in the composition of the present invention include polyethers such as epoxy, acrylic, urethane, polyester, polycarbonate, polysulfone, polyimide, and polyethersulfone, and polyolefins such as low-, medium-, and high-density polyethylene, ethylene-propylene copolymers (random or block configuration), polypropylene-maleic anhydride, polystyrene, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer, ethylene-vinyl acetate, ethylene-acrylic acid copolymer, vinyl chloride-polypropylene copolymer, polyisobutylene, polybutadiene, and crosslinked polyethylene (chemically, thermally, UV, or E-beam (EB) crosslinked), polyphenylene sulfide, polyetheretherketone, polyetherimide, polyarylsulfone, and polypropylene oxide-modified polyethersulfone, or any mixture or combination thereof.

[0049] Particularly useful polymeric materials for the practice of this invention are elastomers and rubber materials. Thus, the polymer component of the composition according to the present invention can contain one or more rubbers or elastomers. Rubbers and elastomers that can be used in accordance with the present invention include those containing olefinic unsaturation, i.e., diene-based rubbers or elastomers, as well as non-diene-based rubber materials or elastomers. The terms "rubber," "rubber material," and "elastomer" may be used interchangeably throughout this specification unless otherwise specified. The term "diene-based rubber" is intended to include both natural and synthetic rubbers, or mixtures thereof. Natural rubber can be used in its raw form and in various processed forms conventionally known in the rubber processing art. Without limitation, synthetic diene-based rubber can be any rubber containing at least one diene monomer that constitutes rubber, either alone or in combination with other monomers. Exemplary diene-based rubber materials suitable for use in the practice of the present invention include, but are not limited to, natural rubber, emulsion styrene-butadiene rubber, solution styrene-butadiene rubber, polybutadiene, polyisoprene, ethylene-propylene-diene rubber (EPDM), butyl rubber and halogenated butyl rubber, acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, polychloroprene, or any combination thereof. Exemplary non-diene-based rubber materials suitable for use in the practice of the present invention include, but are not limited to, ethylene-propylene rubber (EPM), chlorinated polyethylene, chlorosulfonated polyethylene, acrylate rubber, ethylene vinyl acetate rubber, ethylene-acrylic rubber, epichlorohydrin rubber, silicone rubber, fluorosilicone rubber, fluorocarbon rubber, and any combination thereof. Suitable rubbers also include functionalized rubbers and silicon- or tin-bonded rubbers. For example, the rubber may be functionalized with functional groups such as amine, alkoxy, silyl, thiol, thioester, thioether, sulfanyl, mercapto, sulfide, or combinations thereof.The one or more functional groups may be primary, secondary, or tertiary, and may be located at one or both chain ends (e.g., α, ω functionalization), pendant from the polymer backbone, and / or provided within the polymer backbone. The rubbers according to the present invention may also be partially crosslinked. Thus, prior to use in the compositions of the present invention, a portion of the polymer chains of the rubber material may be crosslinked with or without a coupling agent. The polymer component may comprise a single rubber or elastomer, or a mixture or combination of more than one rubber or elastomer, optionally in combination with one or more other polymeric materials, such as those described above. Non-limiting examples of specific rubber materials that can be used in the practice of the present invention include SMR10 rubber available from Weber & Scheer, Vamac® Ultra HT available from DuPont, Noxtite RE461® available from Unimatec, Europrene® 1500 and Europrene SOL® C2525 available from Versalis, or Keltan® 4455 rubber available from Arlanxeo.

[0050] The polymer component typically represents the major component of the composition according to the present invention. It may comprise, for example, 30% by weight or more, based on the total solids weight of the composition. For example, the polymer component may comprise 40% by weight or more, e.g., 50% by weight or more, or 60% by weight or more, based on the total solids weight of the composition. For example, the polymer component may comprise 99% by weight or less, e.g., 95% by weight or less, 90% by weight or less, 85% by weight or less, 80% by weight or less, 75% by weight or less, or 70% by weight or less, based on the total solids weight of the composition. The composition according to the present invention may comprise the polymer component in an amount between any of the above lower and upper limits. For example, the polymer component may be comprised in an amount ranging from 30% by weight to 90% by weight, e.g., from 50% by weight to 80% by weight, based on the total solids weight of the composition.

[0051] In addition to the polymer component, the composition further contains, as a characteristic component, the solid carbon black material according to the present invention, as described in detail above. For example, the composition of the present invention may contain the solid carbon black material in an amount of 1 phr or more, e.g., 2 phr or more, 5 phr or more, 10 phr or more, 20 phr or more, 30 phr or more, 40 phr or more, 50 phr or more, or 60 phr or more. For example, the composition of the present invention may contain the solid carbon black material in an amount of 150 phr or less, e.g., 100 phr or less, 90 phr or less, 80 phr or less, or 70 phr or less. The composition of the present invention may contain the solid carbon black material in an amount between any of the above lower and upper limits. For example, the solid carbon black material may be contained in the composition in an amount ranging from 1 to 100 phr, e.g., 10 to 100 phr, or 30 to 80 phr. As used herein, the term "phr" refers to the parts by weight of the listed respective material (here, the solid carbon black material) per 100 parts by weight of the polymer component.

[0052] The composition according to the present invention may optionally comprise, in addition to the solid carbon black material of the present invention, one or more further fillers. Such optional filler materials include, for example, but are not limited to, conventional carbon black materials, carbon nanotubes, carbon fibers, graphite, and metal fibers, as well as metal compounds such as silica, organosilica, titanium dioxide, calcium carbonate, clay, calcium silicate, zinc sulfide, hydrous alumina, and calcined magnesia. When used, such fillers are typically used in an amount of up to 30 phr, e.g., 0.1 to 20 phr or 1 to 10 phr.

[0053] The composition according to the present invention may also contain at least one vulcanizing agent. Possible vulcanizing agents include any vulcanizing agent known in the art, such as sulfur and sulfur donors. Suitable sulfur donors for the practice of the present invention include, for example, dithioalkanes, dicaprolactam sulfide, polysulfide polymers, sulfur olefin adducts, thiurams, and sulfonamides having at least two sulfur atoms in the sulfur bridge. Preferably, elemental sulfur can be used. Vulcanizing agents are typically used in compositions according to the present invention in amounts ranging from 0.5 to 10 phr, for example, from 1 to 5 phr.

[0054] The composition according to the present invention may further contain one or more other additives commonly used in the art of formulation. Such additives include, for example, curing aids such as primary and secondary vulcanization accelerators, activators and pre-vulcanization inhibitors, processing additives such as oils, waxes, resins, plasticizers, softeners or rheology modifiers, pigments, deflocculants, coupling agents, surfactants, biocides and antidegradants (such as heat or light stabilizers), antioxidants, and antiozonants. Those skilled in the art will select such optional additives and their respective amounts according to the desired properties and / or application of the polymer composition. Useful primary and secondary vulcanization accelerators include, for example, guanidines, dicarbamates, dithiocarbamates, thiurams, thioureas, 2-mercaptobenzothiazoles, benzothiazole sulfonamides, aldehyde amines, amines, disulfides, thiazoles, xanthates, and sulfenamides. A specific example is N-tert-butyl-2-benzothiazylsulfenamide, commercially available from Rhein Chemie Additives under the trade name Rhenogran TBBS-80. One advantage of the present invention is that the vulcanizable polymer composition of the present invention can be cured within a reasonable time with or without a relatively small amount of vulcanization accelerator. Therefore, if an accelerator is used, it can be used in an amount of less than 3 phr, less than 2 phr, or even less than 1 phr, for example, in the range of 0.05 to 3 phr or in the range of 0.5 to 2 phr. This can avoid or minimize the use of accelerators such as DPG due to environmental and / or toxicological concerns. The composition of the present invention may be substantially free of guanidine-type accelerators, such as DPG, o-tolylbiguanidine (OTBG), or 1,3-di-o-tolylguanidine (DOTG). "Substantially free of guanidine-type accelerators" as used herein means that guanidine-type accelerators are not intentionally used. Thus, when present, they are present in compositions according to the present invention as impurities in low amounts that do not significantly affect the properties of the composition, such as amounts of less than 0.1% by weight based on the total solids weight of the composition.The composition according to the present invention may be completely guanidine-type accelerator-free, i.e., contain no guanidine-type accelerators. Suitable vulcanization activators that can be used in the composition according to the present invention include, for example, a combination of zinc oxide and a fatty acid such as stearic acid, lauric acid, palmitic acid, oleic acid, or naphthenic acid. When used, such activators are typically used in an amount of 1 to 10 phr, e.g., 2 to 5 phr.

[0055] The composition according to the present invention may optionally further comprise water and / or one or more organic solvents. For example, water and / or an organic solvent may serve as a dissolving or dispersing medium for the polymer component and the solid carbon black material. The composition according to the present invention may be, for example, a liquid composition such as an aqueous dispersion or an organic dispersion. The composition according to the present invention may be, for example, an ink formulation or a coating or printing composition.

[0056] The composition of the present invention is typically provided as a bulk material. The material can be processed by common plastic or elastomer processing techniques. The composition of the present invention can be obtained, for example, by combining the solid carbon black material of the present invention and any optional ingredients (if used) with a polymer component and mixing them to, for example, disperse the solid carbon black material and any optional ingredients (if used) in the polymer component. Dispersion can be achieved by any means known in the art, such as by mixing, stirring, grinding, kneading, ultrasonication, dissolver, shaker mixer, rotor agitator dispersion assembly, or high-pressure homogenizer, or a combination thereof. For example, a lab mixer with intermeshing rotor geometry can be used. Dispersion can be carried out, for example, until the carbon black material is homogeneously dispersed in the polymer component, with a dispersion index of 95% or greater, preferably 97% or greater, or 99% or greater, as classified according to ASTM D2663-88 Test Method B.

[0057] The preparation of the composition according to the present invention can be carried out, for example, by a multi-step process. First, the solid carbon black material and any non-curing additives, if used, can be added simultaneously or sequentially to the polymer component. The polymer component, solid carbon black material, and additives, if used, can then be mixed at a temperature typically ranging from 40°C to 160°C for a total mixing time of less than 10 minutes, for example, in the range of 2 to 8 minutes. The resulting mixture can then be blended with one or more curing additives at a temperature of less than 115°C for less than 5 minutes, typically less than 3 minutes, and preferably about 2.5 minutes.

[0058] The method can include further steps such as extruding the product or cooling it to room temperature and storing it for further processing. The method can further include a curing step, which can be carried out, for example, by subjecting the composition to thermal curing conditions, for example, at a temperature of 120-200°C for 5 minutes to 3 hours. Curing can be carried out, for example, in a curing press, at a temperature of 140-180°C for 5-60 minutes and a pressure of 100-150 bar.

[0059] As will be appreciated, the compositions of the present invention can be utilized in a variety of technical applications requiring polymeric materials with carbon black fillers, for example, to impart antistatic or conductive properties, color, mechanical reinforcement, and / or low hysteresis. Accordingly, the present invention also relates to articles made from or containing the above-described antistatic or conductive polymer compositions. Non-limiting examples of such articles include tires, tire components (such as tire treads), cable sheaths, tubes, drive belts, conveyor belts, roll covers, shoe soles, seals, profiles, damping elements, coatings, or colored or printed articles. The unusual combination of suitable mechanical properties achievable by rapid curing without the need for large amounts of accelerators and improved hysteresis properties makes the vulcanizable rubber compositions of the present invention particularly interesting for the production of energy-saving tires or tire components, for example, with reduced rolling resistance and heat buildup. Examples of such tires include, but are not limited to, truck tires, passenger tires, off-road tires, aircraft tires, agricultural tires, and earthmover tires.

[0060] The present invention is further illustrated by the following examples. It should be understood that the examples are included for illustrative purposes and should not be construed as limiting the invention. In particular, the scope of protection sought is not limited by the specific examples disclosed below, but rather should be accorded the full scope of the appended claims, including any equivalents thereof. [Example]

[0061] All parts and percentages referred to herein are by weight unless otherwise indicated.

[0062] Carbon Black Materials As a reference, Printex® 60, a non-oxidizing furnace black commercially available from Orion Engineered Carbons, Inc. (hereinafter referred to as Carbon Black A) was used.

[0063] Additionally, a conventional acidic oxidized carbon black (hereafter referred to as Carbon Black B) was used, which had a similar surface area and structure to the reference black and was obtained by oxidation of Printex® 60 carbon black, commercially available from Orion Engineered Carbons.

[0064] Approximately 5 kg of carbon black A or B powder was wet-beaded. To this end, the powder was introduced into a static batch mixer (a so-called "Papenmeier" type GRP625 / 1.0, manufactured by Geppert Ruehrtechnik). Deionized water was then slowly added under stirring (300 rpm) until the carbon black began to granulate, typically at a weight ratio of approximately 1:1. The stirring speed was then increased to 600-800 rpm. The resulting mixture was then homogenized for 10 minutes at 28 rpm on a roller block with a 600 mm long, 350 mm diameter plastic drum. The bead material was then dried in an oven at 120 °C until the residual moisture content was less than 1%. The particle size distribution of the pellets thus obtained was measured as shown below.

[0065] A carbon black material according to the present invention (hereinafter referred to as Carbon Black C) was further prepared by treating Carbon Black B with aqueous sodium hydroxide solution. To this end, approximately 5 kg of Carbon Black B powder was wet-beaded according to the procedure described above, but using 0.4 M aqueous sodium hydroxide solution instead of deionized water.

[0066] The properties of the different beaded carbon blacks employed are summarized in Table 1.

[0067] [Table 1]

[0068] Applied methods for carbon black characterization BET surface area was measured by nitrogen adsorption according to ASTM D6556-17.

[0069] Statistical thickness surface area (STSA) was measured according to ASTM D6556-17.

[0070] Iodine adsorption capacity (IAN) was measured according to ASTM D1510-19.

[0071] Oil absorption number (OAN) was measured according to ASTM D2414-18.

[0072] The oil absorption (COAN) of the compressed samples was measured according to ASTM D3493-18.

[0073] pH was measured using a WTW inoLab Multi9420IDS according to D1512-15b, Test Method B - Sonic Slurry.

[0074] Tinting strength was measured according to ASTM D3265-17.

[0075] Blackness M Y was measured according to DIN 55979-1989.

[0076] Volatiles at 950 °C were measured using a Fa.LECO Instruments (TGA-701) thermogravimetric analyzer according to the following procedure. The weighing dish was dried at 650 °C for 30 minutes. The carbon black material was stored in a desiccator with a desiccant before measurement. The baked-out weighing dish was loaded into the instrument, weighed, and filled with 0.5 g to 10 g of carbon black material. The TGA oven containing the loaded dish was then gradually heated to 105 °C under automated software control, allowing the sample to dry until a constant mass was achieved. The dish was then closed with a lid, and the oven was purged with nitrogen (99.9% by volume) and heated to 950 °C. The oven temperature was maintained at 950 °C for 7 minutes. The volatile content at 950 °C was calculated using the following equation:

[0077]

number

[0078] The carboxylic acid groups per unit mass were measured according to the following procedure: Carbon black was dried overnight in a compartment dryer set at a temperature of 125°C. The hot carbon black material was removed from the dryer and allowed to cool in a desiccator containing a desiccant. Three thoroughly cleaned and dried Erlenmeyer flasks were each filled with m CB A total of 1.5±0.1 g of carbon black material was weighed, and 25 mL of 0.05 molar aqueous sodium bicarbonate solution (Titrisol grade diluted with bi-distilled water) was added to each. The air in the flask was replaced with nitrogen gas, and the flask was sealed with a plug and further secured by taping with parafilm. The flask was placed in a shaker at 100 rpm overnight. The resulting suspension was then pressure filtered at 5 bar using nitrogen gas. 10 mL of each filtrate was transferred to a beaker. 20 mL of 0.025 molar sulfuric acid (Titrisol grade diluted with bi-distilled water) was added to each beaker, and the carbonate was removed by boiling briefly. The sample was then titrated back to pH 6.5 using 0.05 molar sodium hydroxide solution (Titrisol grade diluted with bi-distilled water). The required amount of sodium hydroxide solution, V NaOH was measured in mL with an accuracy of three decimal places. Two blanks were measured and the required amount of sodium hydroxide solution was averaged (V ブランク,平均 The concentration of carboxyl groups in μmol / g was calculated for all three samples using the following formula, and the resulting values ​​were averaged:

[0079]

number

[0080] The oxygen content was measured by quantitative elemental analysis using an automatic elemental analyzer (vario EL cube elemental analyzer manufactured by Elementar Analysensysteme) in accordance with DIN 51732-2014-07. 4 mg ± 1 mg of dry carbon black to be analyzed was weighed into a tin capsule on a scale with an accuracy of 1 μg. The filled capsule was then sealed in a capsule press under a helium atmosphere. The sample thus prepared was then introduced into a calibrated vario EL cube elemental analyzer, and its oxygen content was analyzed.

[0081] Pellet size distribution was measured according to ASTM D1511-10.

[0082] Aggregate size distribution was measured by light scattering using a Brookhaven BI-DCP disc centrifuge according to ISO15825:2015-06.

[0083] Preparation of vulcanizable rubber compositions of Examples 1 to 3 Vulcanizable rubber compositions having the formulations shown in Table 2 were prepared using different bead-shaped carbon blacks A to C according to the following procedure.

[0084] The preparation was carried out using a multi-stage mixing procedure, with each mixing step carried out in an internal mixer with intermeshing rotor geometry (GK1.5E).

[0085] First, the rubber components were added to the mixing chamber of the internal mixer, operated at 45 rpm and a chamber temperature of 40°C, and plasticized for 30 seconds. Then, TDAE, ZnO, stearic acid, and half the amount of each carbon black were added and mixed for 75 seconds. The ram was lifted and washed, after which the remaining carbon black components were added, followed by an additional 135 seconds of mixing. During this step, it was ensured that the maximum temperature did not exceed 160°C. The internal mixer's fill factor was 0.68.

[0086] After storage for at least 12 hours, in a second mixing step the mixture was stirred for 150 seconds in an internal mixer at 48 rpm and a chamber temperature of 60° C. During this step it was ensured that the maximum temperature did not exceed 155° C.

[0087] Subsequently, sulfur and TBBS-80 were added to the mixture and stirred in an internal mixer at 33 rpm and a chamber temperature of 40° C. for 2 minutes. During this step, it was ensured that the maximum temperature did not exceed 110° C. The resulting mixture was then cooled to obtain the respective vulcanizable rubber compositions.

[0088] [Table 2]

[0089] Curing of the vulcanizable rubber compositions of Examples 1 to 3 The vulcanizable rubber compositions of Examples 1 to 3 were cured in a curing press for 20 minutes at 150° C. The applied pressure was 120 to 150 bar.

[0090] The properties of the cured rubber compositions thus obtained were tested as follows.

[0091] Mooney viscosity (ML(1+4)100°C) was measured according to ISO289-1:2015.

[0092] The hardness was measured according to DIN 53 505.

[0093] The bound rubber content was measured according to the following procedure. Approximately 0.2 g of rubber sample was cut into small pieces, weighed using an analytical balance, and placed in a wire basket (320 mesh, stainless steel, 22 mm diameter, 40 mm height) filled with glass wool, ensuring that the sample did not come into contact with the wire basket. The sample-containing basket was placed in a 100 mL flask with a screw cap, and 50–60 mL of toluene (analytical grade) was added to achieve a minimum fill level of 20 mm above the flask bottom. The flask was left at a temperature of 23 ± 2 °C for 7 days, whereby the flask was swirled every morning and night. The toluene was replaced after 1–3 days. After 7 days, the basket with the bound rubber gel inside was removed from the flask and the solvent was allowed to evolve overnight in a fume hood. The sample was then dried overnight in a tray dryer until a constant mass was achieved. After cooling to room temperature in a desiccator, the sample was weighed (m(dried gel)). The weight percentage of bound rubber relative to the original sample mass was calculated using the following formula:

[0094]

number

[0095] The mass of the carbon black filler in the gel was assumed to be the same as the mass of the carbon black filler in the original sample (m(filler, original sample)).

[0096] The tensile strength, elongation at break, modulus at 100%, modulus at 200%, modulus at 300% and modulus at 500% were determined according to DIN 53 504.

[0097] The tear resistance was determined according to DIN ISO 34-1:2016-09, method B, deformation (b) using notched corner specimens, and the force required to enlarge the preformed notch was measured.

[0098] The results obtained are summarized in Table 3.

[0099] [Table 3]

[0100] The results in Table 3 demonstrate that the use of oxidized carbon black in rubber compositions can result in rubber articles with significantly improved hysteresis properties, as evidenced by an increase in bound rubber, compared to a corresponding reference carbon black that has not been oxidized (see Examples 2 and 3 compared to Example 1). However, the use of conventional acid-functional oxidized carbon black significantly reduces the mechanical properties of the cured rubber composition, as evidenced by the significant decrease in modulus and tensile strength of Example 2 relative to Example 1. The use of oxidized carbon black according to the present invention (Example 3) significantly improves these mechanical properties compared to conventional acid-functional oxidized carbon black, without adversely affecting the bound rubber.

[0101] Thus, the cured rubber composition incorporating the oxidized carbon black of the present invention (Example 3) exhibits mechanical properties that more closely mirror those achieved with the corresponding unoxidized reference carbon black (Example 1), while exhibiting significantly improved hysteresis characteristics as indicated by the increase in bound rubber. The cured rubber composition incorporating the oxidized carbon black of the present invention (Example 3) also exhibits superior tear resistance compared to Comparative Examples 1 and 2.

[0102] Preparation of vulcanizable rubber compositions with different accelerator contents (Examples 4 to 6) Furthermore, vulcanizable rubber compositions having the formulations shown in Table 4 were prepared using bead-shaped carbon blacks A to C, and the amount of N,N-diphenylguanidine (DPG) vulcanization accelerator was systematically varied.

[0103] Examples 1-3 were prepared as described above for Examples 1-3, except that TDAE was not used and the DPG accelerator (if any) was added to the rubber mix along with the sulfur and TBBS-80 components, respectively. Examples 4-6 each involve the preparation of a series of four curable rubber compositions with different amounts of DPG accelerator, which ranged from 0 phr (variant a) to 0.5 phr (variant b), 1.0 phr (variant c), and 2.0 phr (variant d), as described in Table 4.

[0104] [Table 4]

[0105] Curing of vulcanizable rubber compositions Each of the vulcanizable rubber compositions according to Examples 4 to 6(a) to (d) was cured in a curing press at 160° C. for 60 minutes, with an applied pressure of 120 to 150 bar.

[0106] Following the curing of the rubber compositions, the change in torque versus curing time was measured using a moving die rheometer (MDR2000E) according to ISO 6502-3: 2018. The measured data are plotted in Figure 1 to show the different curing characteristics of the rubber compositions.

[0107] The time to maximum torque in a torque versus time plot is the "time to set," t 100 It is considered that the time t reported as an index of hardening in Table 5 below 95 are the corresponding t in the torque versus time plot. 100 This corresponds to the time it takes to reach 95% of the torque value achieved in step 1.

[0108] Each time t 95 The rubber compositions cured for (minutes rounded up to the next whole number, see Table 5 below) were tested for their properties as follows.

[0109] Mooney viscosity, hardness, modulus, elongation at break and tear resistance were measured as described above for Examples 1-3.

[0110] Furthermore, the loss factor tanδ and the complex modulus E* were measured according to DIN 53 513 in strain-controlled mode (1±0.5 mm) on cylindrical specimens (height 10 mm and diameter 10 mm) at 60°C and a frequency of 16 Hz.

[0111] Ball rebound was further measured according to a test method based on ASTM 3574 and DIN ISO 8307 as follows: A cylindrical test specimen with a diameter of 35 mm and a height of 19 mm was heated to 60±0.2°C. The circular areas of the test specimen were ensured to be smooth and parallel to each other. A steel ball with a diameter of 19 mm was dropped from a height of 500 mm through a drop tube onto one of the circular areas of the test specimen. The height corresponds to the distance between the lowest point of the steel ball and the point of impact on the test specimen. The time interval between the first and second impacts of the steel ball on the test specimen was measured by a light barrier positioned near the top of the impact point on the test specimen. The time resolution of the light barrier was 10 -4 The time intervals measured over five experiments per test sample were averaged and applied to calculate the rebound height. The rebound height was then again used to calculate the ball rebound, which corresponds to the percentage ratio of the rebound height to the drop height.

[0112] The results obtained are summarized in Table 5.

[0113] [Table 5]

[0114] Figure 1 and Table 5 95 demonstrate that rubber compositions containing oxidized carbon black according to the present invention (Examples 6a-d) vulcanize significantly faster than rubber compositions containing conventional oxidized carbon black with the same amount of DPG accelerator (Examples 6a-d). The rubber compositions containing oxidized carbon black according to the present invention (Examples 6a-d) exhibit practically the same cure rate (e.g., t) as the corresponding rubber compositions containing reference carbon black that has not been oxidized (Examples 4a-d). 95). Thus, the use of oxidized carbon black according to the present invention allows vulcanization in commercially reasonable time periods with relatively small amounts of DPG accelerator or even no DPG accelerator compared to conventional oxidized carbon black, thus minimizing or avoiding the use of potentially harmful and expensive accelerator materials such as DPG. Furthermore, as shown by the data in Table 5, the oxidized carbon black according to the present invention, like conventional oxidized carbon black, imparts improved hysteresis properties to rubber compositions, as evidenced by the reduced loss factor tan δ and increased ball rebound force relative to the corresponding non-oxidized reference carbon black in Table 5, yet without the drawback of significantly slower cure associated with the use of conventional oxidized carbon black. As evidenced by the data in Table 5, rubber compositions incorporating oxidized carbon black according to the present invention further exhibit acceptable mechanical properties, with tear resistance being further improved compared to corresponding rubber compositions incorporating the reference black.

Claims

1. A solid carbon black material comprising an oxidized carbon black having a pH greater than 7 as measured according to ASTM D1512-15b Test Method B - Sonic Slurry.

2. 2. The solid carbon black material according to claim 1, wherein the oxidized carbon black has a pH of at least 8, such as in the range of 8 to 12, as measured in accordance with ASTM D1512-15b Test Method B - Sonic Slurry.

3. 3. The solid carbon black material according to claim 1, wherein the oxidized carbon black has a volatile content, as measured by thermogravimetric analysis at 950°C, in an amount of more than 1.0 wt.%, such as at least 2.0 wt.%, or at least 3.0 wt.%, based on the total weight of the oxidized carbon black; and / or an oxygen content, as measured by elemental analysis, in an amount of at least 0.5 wt.%, such as at least 1.0 wt.%, or at least 2.0 wt.%, based on the total weight of the oxidized carbon black.

4. The solid carbon black material according to any one of claims 1 to 3, wherein the oxidized carbon black is ozone-oxidized carbon black and / or oxidized furnace black.

5. 5. The solid carbon black material according to claim 1, wherein the oxidized carbon black comprises carboxylate groups, preferably alkali metal carboxylates, preferably in an amount of at least 100 μmol / g, such as in the range of 100 to 300 μmol / g.

6. 6. The solid carbon black material according to claim 1, wherein the oxidized carbon black having a pH of greater than 7 has less than 20 μmol / g of carboxylic acid groups, e.g., is substantially free of carboxylic acid groups.

7. 7. The solid carbon black material according to claim 1, wherein the solid carbon black material is in the form of a powder or beads.

8. The solid carbon black material according to any one of claims 1 to 7, wherein the oxidized carbon black has one or more or all of the following: (a) 30-500m ２ / g, preferably 50 to 200m ２ / g range statistical thickness surface area measured according to ASTM D6556-17; (b) 50-500m ２ / g, preferably 70 to 300 m ２ / g; BET surface area measured according to ASTM D6556-17; (c) an oil absorption number (OAN) measured according to ASTM D2414-18 in the range of 50 to 150 mL / 100 g, preferably 70 to 130 mL / 100 g; (d) oil absorption of a compressed sample (COAN), measured according to ASTM D3493-18, in the range of 50 to 150 mL / 100 g, preferably 80 to 120 mL / 100 g; (e) an iodine adsorption capacity, measured according to ASTM D1510-19, in the range of 20 to 300 mg / g, preferably 40 to 100 mg / g.

9. 9. The solid carbon black material according to claim 1, wherein the solid carbon black material consists of an oxidized carbon black having a pH of greater than 7, as measured in accordance with ASTM D1512-15b Test Method B - Sonic Slurry.

10. 10. A method for producing the solid carbon black material according to any one of claims 1 to 9, comprising: (i) providing an oxidized carbon black; (ii) treating the oxidized carbon black with a base, preferably an aqueous alkali metal hydroxide solution; (iii) optionally, wet-beading the oxidized carbon black.

11. 11. The method for producing a solid carbon black material according to claim 10, wherein the base is used in at least an equimolar amount relative to the acidic groups in the oxidized carbon black.

12. (i) a polymer component, and (ii) the solid carbon black material according to any one of claims 1 to 9, A composition comprising:

13. 13. The composition of claim 12, wherein the polymer component comprises a mixture of natural rubber, emulsion styrene-butadiene rubber, solution styrene-butadiene rubber, polybutadiene, polyisoprene, ethylene-propylene-diene rubber EPDM, ethylene-propylene rubber EPM, halogenated butyl rubber, butyl rubber, chlorinated polyethylene, chlorosulfonated polyethylene, acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, polychloroprene, acrylate rubber, ethylene-vinyl acetate rubber, ethylene-acrylic rubber, epichlorohydrin rubber, silicone rubber, fluorosilicone rubber, fluorocarbon rubber, or any combination thereof.

14. 14. The composition of claim 13, further comprising one or more additives selected from vulcanizing agents, accelerators, activators, processing additives such as oils, resins, softeners, pigments, waxes, deflocculants, and antioxidants.

15. 15. The composition of claim 13 or 14, which is substantially free of guanidine-type enhancers.

16. The composition of claim 12 further comprising water and / or one or more organic solvents.

17. 17. The composition of claim 16, wherein the composition is a liquid composition, preferably an aqueous dispersion, an organic dispersion, an ink formulation, a coating composition or a printing composition.

18. The composition according to any one of claims 12 to 17, wherein the composition comprises the solid carbon black material in an amount of 1 to 100 parts by weight, preferably 10 to 100 or 30 to 80 parts by weight, per 100 parts by weight of the polymer component.

19. An article prepared from the composition of any one of claims 12 to 18.

20. 20. The article of claim 19, which is a tire, a tire component (such as a tire tread), a cable sheath, a tube, a drive belt, a conveyor belt, a roll cover, a shoe sole, a seal member, a profile, a damping element, a coating, or a colored or printed article.

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