Modified carbon black as well as preparation method and application thereof

Abstract

The invention relates to the technical field of carbon black modification, and particularly discloses modified carbon black and a preparation method and application thereof.The surface of the carbon black is oxidized through sodium ferrate under the alkaline condition, then aniline monomers are subjected to in-situ polymerization in the acid environment, and a coating layer is formed; finally, the modified carbon black with high antistatic property (the resistivity is as low as 0.02-0.1 omega.cm) and excellent dispersity (the dispersity reaches grade 1) is obtained. The method is simple, environment-friendly and safe; the prepared modified carbon black is high in antistatic property and good in dispersity; the prepared modified carbon black is wide in application field.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon black modification, and particularly relates to a modified carbon black, a preparation method thereof, and an application thereof. Background Art

[0002] Carbon black is a black powdery substance formed by the incomplete combustion or pyrolysis of hydrocarbons in the gas phase under strictly controlled process conditions. Its main component is elemental carbon, and it contains a small amount of oxygen, hydrogen, sulfur, etc. The carbon black particles are approximately spherical in shape, and the particle size range is 10 - 500 μm. Most particles are fused or aggregated into three-dimensional branched or fibrous aggregates.

[0003] With the research on carbon black, its application fields are constantly expanding. Currently, carbon black is commonly used in rubber products, the plastics industry, coatings and inks, chemical fibers and leather, electronic components, the metallurgy and carbon industry, the new energy industry, etc. However, different industries have different requirements for its performance. Therefore, it needs to be modified to meet the requirements of different industries. Some need to increase dispersibility and wear resistance, while some need to increase antistatic properties and thermal conductivity, etc. Among them, modification mainly includes graft modification, fatty acid modification, oxidation modification, coating modification and other technical means. Most modification processes involve strong acids, ozone, heavy metals, etc., and all have more or less defects, such as complex process, low safety, and difficult post-treatment of waste liquid, which seriously restricts the development of the industry. Compared with the traditional strong acid oxidation or heavy metal modification process, the present invention uses sodium ferrate (Na2FeO4) oxidation combined with polyaniline coating to avoid the generation of toxic waste liquid, and the process is more environmentally friendly. Summary of the Invention

[0004] The first technical problem to be solved by the present invention is: to provide a preparation method of modified carbon black, which overcomes the defects of the prior art, has a simple and environmentally friendly process, and the prepared modified carbon black has excellent antistatic properties and dispersibility.

[0005] The second technical problem to be solved by the present invention is: to apply the above-mentioned modified carbon black to the production of rubber, coatings and explosives.

[0006] To solve the above technical problems, the present invention provides the following technical solutions: A preparation method of modified carbon black, comprising the following steps: a. Under the protection of an inert gas, add carbon black to a NaOH solution (pH value is 12 - 14) with a mass 2 times that of the carbon black, add sodium ferrate (purity ≥ 90%) with a mass 0.1 - 0.3 times that of the carbon black, and then add deionized water with a mass 0.05 - 0.1 times that of the total mass of the carbon black and sodium ferrate; react at 40 - 60 °C for 4 - 8 hours, and stir at a speed of 300 - 500 r / min simultaneously; b. After the reaction in step a is completed, add 0.1 M dilute hydrochloric acid to adjust the pH to neutral to terminate the oxidation; then centrifuge to separate the carbon black and wash it with deionized water until there is no Fe 3+ ; then vacuum dry (vacuum degree 40 - 60 kPa) at 60 - 80 °C for 4 - 6 hours; c. Disperse the carbon black obtained after drying in step b in 1 M HCl solution with a mass 20 times that of the carbon black, and ultrasonically treat (400 W) for 30 minutes; then add aniline monomer (mass ratio of carbon black to aniline is 1:0.3 - 0.5) under the condition of ice bath temperature control (0 - 5 °C), and then slowly dropwise add ammonium persulfate (molar ratio to aniline is 1:1), and react for 12 - 24 hours; d. Filter the product obtained in step c by suction, wash the obtained solid with absolute ethanol until the filtrate is colorless, and dry it in vacuum (vacuum degree 40 - 60 kPa) at 60 °C to constant weight to obtain modified carbon black.

[0007] Preferably, the inert gas is nitrogen or argon, and the carbon black is acetylene carbon black.

[0008] Preferably, in step a, the pH value of the NaOH solution is 13, the addition amount of sodium ferrate is 0.2 times the mass of the carbon black, and the added mass of deionized water is 0.08 times the total mass of the carbon black and sodium ferrate in the solution; react at 50 °C and 400 r / min for 6 hours.

[0009] Preferably, the drying in step b is vacuum drying at 70 °C for 5 hours.

[0010] Preferably, in step c, the mass ratio of carbon black to aniline is 1:0.4, and react for 18 hours.

[0011] A kind of modified carbon black: the modified carbon black prepared by the above method.

[0012] An application of a kind of modified carbon black: the application of the modified carbon black prepared by the above method in antistatic products required in industries such as explosives, rubber, and coatings.

[0013] Due to the adoption of the above technical solution, the beneficial effects of the present invention are: The present invention oxidizes the surface of carbon black by sodium ferrate (Na2FeO4) under alkaline conditions, and then in-situ polymerizes aniline monomer in an acidic environment to form a coating layer, and finally obtains modified carbon black with both high antistatic property (resistivity as low as 0.02 - 0.1 Ω·cm) and excellent dispersibility (dispersion degree reaches level 1). This preparation method overcomes the defects brought by the existing technology of modifying carbon black with strong acids, ozone, heavy metals, etc. The obtained modified carbon black has good antistatic performance and can be applied to industries such as explosives, rubber, and coatings.

[0014] In summary, the method of the present invention is simple, environmentally friendly and safe; the prepared modified carbon black has strong antistatic properties and good dispersibility; and the prepared modified carbon black has a wide range of applications. DETAILED DESCRIPTION

[0015] The technical solution of the present invention is further described below in conjunction with embodiments: The carbon black required for the experiment is acetylene carbon black produced by Xinxiang Delong Chemical Co., Ltd. Example 1 Preparation of modified carbon black a. Under nitrogen protection (to prevent Na2FeO4 from being decomposed by CO2), add 100g of carbon black to 200g of NaOH solution (pH 12), add 10g of sodium ferrate (purity ≥90%), and then add 11g of deionized water; react at 40℃ for 8 hours, while stirring at 300r / min (to ensure uniform mixing); b. After the reaction in step a is completed, add 0.1M dilute hydrochloric acid to adjust the pH to neutral to terminate the oxidation; then centrifuge to separate the carbon black and wash with deionized water until there is no Fe 3+ (Can be detected with KSCN solution, no red Fe(SCN) 3- Then vacuum dry at 60℃ (vacuum degree 40kPa) for 6 hours; c. The carbon black obtained after drying in step b was dispersed in 2000 g of 1M HCl solution and ultrasonically treated (400 W) for 30 minutes; then 30 g of aniline monomer was added under ice bath temperature control (0-5°C), and then 73 g of ammonium persulfate was slowly added dropwise, and the reaction was carried out for 12 hours; d. The product obtained in step c was filtered, and the obtained solid was washed with anhydrous ethanol until the filtrate was colorless, and dried at 60°C in vacuum (vacuum degree 40 kPa) to constant weight to obtain 129.5 g of modified carbon black.

[0016] Example 2 Preparation of modified carbon black a. Under argon protection, add 100 g of carbon black to 200 g of NaOH solution (pH 14), add 30 g of sodium ferrate (purity ≥ 90%), and then add 6.5 g of deionized water; react at 60°C for 4 hours while stirring at 500 r / min (to ensure uniform mixing); b. After the reaction in step a is completed, add 0.1M dilute hydrochloric acid to adjust the pH to neutral to terminate the oxidation; then centrifuge to separate the carbon black and wash with deionized water until there is no Fe 3+ ; Then vacuum dry at 80°C (vacuum degree 60kPa) for 4 hours; c. Disperse the carbon black obtained after drying in step b in 2000 g of 1M HCl solution, and ultrasonically treat it (400 W) for 30 minutes; then add 50 g of aniline monomer under the condition of ice bath temperature control (0 - 5°C), and slowly dropwise add 122.6 g of ammonium persulfate, and react for 24 hours; d. Filter the product obtained in step c by suction filtration, wash the obtained solid with absolute ethanol until the filtrate is colorless, and dry it to constant weight at 60°C under vacuum (vacuum degree 60 kPa) to obtain 163 g of modified carbon black.

[0017] Example 3 Preparation of Modified Carbon Black III a. Under nitrogen protection, add 100 g of carbon black to 200 g of NaOH solution (pH = 13), add 20 g of sodium ferrate (purity ≥ 90%), and then add 9.6 g of deionized water; react at 50°C for 6 hours while stirring at a speed of 400 r / min; b. After the reaction in step a is completed, add 0.1M dilute hydrochloric acid to adjust the pH to neutral to terminate the oxidation; then centrifuge and separate the carbon black, and wash it with deionized water until there is no Fe 3+ ; then dry it under vacuum (vacuum degree 50 kPa) at 70°C for 5 hours; c. Disperse the carbon black obtained after drying in step b in 2000 g of 1M HCl solution, and ultrasonically treat it (400 W) for 30 minutes; then add 40 g of aniline monomer under the condition of ice bath temperature control (0 - 5°C), and slowly dropwise add 98 g of ammonium persulfate, and react for 18 hours; d. Filter the product obtained in step c by suction filtration, wash the obtained solid with absolute ethanol until the filtrate is colorless, and dry it to constant weight at 60°C under vacuum (vacuum degree 50 kPa) to obtain 149.3 g of modified carbon black.

[0018] Example 4 Preparation of Modified Carbon Black IV a. Under argon protection, add 100 g of carbon black to 200 g of NaOH solution (pH = 14), add 30 g of sodium ferrate (purity ≥ 90%), and then add 6.5 g of deionized water; react at 55°C for 4 hours while stirring at a speed of 500 r / min (ensure uniform mixing); b. After the reaction in step a is completed, add 0.1M dilute hydrochloric acid to adjust the pH to neutral to terminate the oxidation; then centrifuge and separate the carbon black, and wash it with deionized water until there is no Fe 3+ ; then dry it under vacuum (vacuum degree 60 kPa) at 80°C for 4 hours; c. Disperse the carbon black obtained after drying in step b in 2000 g of 1M HCl solution, and ultrasonically treat it (400 W) for 30 minutes; then add 50 g of aniline monomer under the condition of ice bath temperature control (0 - 5°C), and slowly dropwise add 122.6 g of ammonium persulfate, and react for 24 hours; d. Filter the product obtained in step c by suction filtration. Wash the obtained solid with absolute ethanol until the filtrate is colorless, and dry it at 60 °C under vacuum (vacuum degree: 60 kPa) until constant weight to obtain 147 g of modified carbon black.

[0019] Example 5 Preparation of Modified Carbon Black V Adjust the pH of the NaOH solution in step a of Example 3 to 10, and keep other conditions unchanged to prepare 143.6 g of modified carbon black.

[0020] Example 6 Preparation of Modified Carbon Black VI Adjust the reaction temperature in step a of Example 3 to 65 °C, and keep other conditions unchanged to prepare 137.8 g of modified carbon black.

[0021] Results and Analysis of Examples 1 - 6 Compared with Untreated Acetylene Carbon Black Conduct relevant tests on the untreated acetylene carbon black purchased in the same batch and the modified carbon black obtained in Examples 1 - 6: 1. Measure the resistivity of the untreated acetylene carbon black (blank control) purchased in the same batch and the modified carbon black obtained in Examples 1 - 6 according to the method for determining the resistivity of acetylene carbon black in GB / T3781.9 - 93. The results are shown in Table 1: Table 1 Resistivity (Ω·cm) Results of Untreated Carbon Black and Modified Carbon Black in Examples 1 - 6

[0022] It can be seen from the above data that the resistivity of the products in Examples 2 - 4 is similar, and their electrical conductivity is better than that of other products. In particular, the electrical conductivity is significantly improved compared with that of untreated carbon black, indicating that its antistatic performance has been significantly enhanced.

[0023] 2. Prepare rubber with untreated acetylene carbon black (blank control) and the modified carbon black obtained in Examples 1 - 6. By weight, 50 parts of NR natural rubber, 50 parts of styrene - butadiene rubber, 3 parts of calcium carbonate, 5 parts of 4010NA, 2 parts of stearic acid, 2 parts of sulfur, 7 parts of aromatic oil, and 50 parts of modified carbon black. Test the following properties of the prepared rubber according to the national standard method and predict the results: carbon black dispersion, hardness, 300% modulus at 100% elongation (MPa), tensile strength (MPa), elongation at break (%), tear strength (kN / m), and after aging at 100 °C (hardness, 300% modulus at 100% elongation (MPa), tensile strength (MPa), elongation at break (%), tear strength (kN / m)); the results are shown in Table 2: Table 2 Test Results of Rubber Prepared with Untreated Carbon Black and Modified Carbon Black in Examples 1 - 6

[0024] From the above data, it can be concluded that: the stronger the alkalinity of the NaOH solution, the more sufficient the oxidation of carbon black. In Example 5, the NaOH solution with a pH value of 10 was used, and its alkalinity was relatively low. The rapid decomposition and inactivation of Na2FeO4 would lead to poor dispersion and interfacial bonding of the modified carbon black, and its performance was close to that of untreated carbon black. The reaction temperature also had a great influence on the modification. After the reaction temperature in Example 6 was increased to 65 °C, the half-life of Na2FeO4 was significantly shortened. Although the oxidation efficiency increased, the yield decreased significantly. In Examples 2 and 4, due to the increase in the coating materials, most of the product indicators were better than those of other examples, mainly because the alkalinity of the NaOH solution was the strongest, and at the same time, the amount of polyaniline used for coating carbon black was large. However, its reaction temperature was relatively high, and the product yield was relatively low. Therefore, in practical applications, attention should be paid to reasonably configuring the alkalinity of the NaOH solution, the reaction temperature, and the dosage of aniline. Although the dispersion degree of Examples 2 and 4 was slightly better, considering the yield and cost comprehensively, Example 3 was the optimal solution with the best cost performance.

[0025] Example 7 Preparation of Explosive I 1. Add 80 kg of ammonium nitrate and 7.5 kg of sodium nitrate into a heating kettle with stirring, add an appropriate amount of water, start stirring and heating, and control the heating temperature at about 120 °C to completely dissolve ammonium nitrate and sodium nitrate to form a uniform aqueous solution; the stirring speed is generally 150 r / min, and the dissolution time is about 25 minutes until the solution is clear and transparent without solid particles; after the dissolution is completed, keep the aqueous solution warm for standby, and keep the temperature at 95 °C; 2. In another heating kettle with stirring, add 6 kg of paraffin, 2 kg of sorbitan monooleate (Span80), and 0.3 kg of benzoic acid, heat and stir, and control the heating temperature at 85 °C to completely melt and mix paraffin, Span80, and benzoic acid evenly to form an oil phase; the stirring speed is 130 r / min, and the mixing time is about 13 minutes; 3. Slowly add the prepared aqueous solution to the oil phase system, and at the same time start a high-shear emulsifier, and control the rotation speed of the emulsifier at 4000 r / min. During the emulsification process, keep the system temperature at 85 °C, and the emulsification time is about 8 minutes to fully emulsify the aqueous phase and the oil phase to form a stable latex matrix; 4. Slowly add 6.5 kg of the modified carbon black prepared in Example 3 to the emulsified latex matrix under stirring (stirring speed 100 r / min), and continue stirring for 8 minutes to uniformly disperse the modified carbon black in the latex matrix to obtain an emulsion explosive.

[0026] Example 8 Preparation of Explosive II Replace the modified carbon black in Example 7 with untreated carbon black purchased in the same batch, and keep other conditions unchanged.

[0027] Results and Analysis of Examples 7-8 The products of Examples 7 and 8 were subjected to BAM friction sensitivity (German Federal Institute for Materials Research and Testing standard (DIN EN13631-3), load 360 N, pendulum angle 90°), BAM impact sensitivity (falling weight 10 kg, falling height 50 cm), DSC (differential scanning calorimetry), TGA (thermogravimetric analysis), combustion tube, antistatic accumulation ability, and conductivity test (burning rate). The results are shown in Table 3.

[0028] Table 3 Test Results of the Products of Examples 7-8

[0029] Testing the explosives prepared in Example 7 and Example 8 found that: the modified carbon black reduced the friction sensitivity of the explosive by more than 50%, the impact sensitivity by more than 70%, increased the decomposition temperature by 35 °C, decreased the burning rate to 1 / 3, and was more suitable for applications in high-temperature environments; the conductivity was increased to 0.1 - 1 S / cm, effectively solving the risk of static electricity accumulation, and the electrostatic sensitivity reached the industrial safety standard (>100 mJ), avoiding premature detonation caused by excessive conductivity. This modified carbon black can be applied to the production of explosives.

[0030] Example 9 Preparation of Coating I Add 24 kg of xylene to the reaction kettle, start stirring at 300 r / min, and then sequentially add 30 kg of waterborne epoxy resin CYDW-100, 3 kg of waterborne polyurethane resin emulsion 1624, 17 kg of modified carbon black, 13 kg of mica powder, 1.25 kg of leveling agent BD-3033, and 0.75 kg of dispersant SDJ8009. After all are added, increase the rotation speed to 600 r / min and stir for 10 minutes, then increase to 1000 r / min and stir for 10 minutes. Finally, add 12 kg of aliphatic diisocyanate monomer. After adding, increase the stirring speed to 1000 r / min and stir for 20 minutes to obtain a fully mixed coating.

[0031] Example 10 Preparation of Coating II Replace the modified carbon black in Example 9 with untreated carbon black purchased in the same batch, and keep other conditions unchanged.

[0032] Results and Analysis of Examples 9-10 The products of Examples 9-10 were sprayed onto an aluminum plate to prepare a coating with a thickness of 2 mm and cured at 25 °C for 24 hours to obtain an electromagnetic wave absorbing coating. Then, performance tests were carried out on the electromagnetic wave absorbing coating. The test results are shown in Table 4: Appearance: Observe the electromagnetic wave absorbing coating under scattered daylight by visual inspection for flatness and phenomena such as sagging, blooming, pinholes, cracking, and peeling. Adhesion: Conduct according to the provisions of 9.4.3 in GB / T5210-2006. Hardness: It shall be carried out in accordance with the provisions of the pencil method for determining film hardness in GB / T 6739-2006.

[0033] Corrosion resistance: It shall be carried out in accordance with the provisions of GB / T 9274-2019. The acid resistance, alkali resistance and salt water resistance of the coating are tested. The corrosion media are 3wt% H2SO4 solution, 3wt% NaOH solution and 2wt% NaCl solution respectively. The specific steps are as follows: Place the sample coating face up horizontally, drop 0.1 mL of the corrosion medium at each point, and keep at least a 20 mm interval between the centers of adjacent liquids; Place the sample at 23 °C for 24 h to allow it to fully contact the air without other interference; Then thoroughly wash the surface of the coating with clean water and immediately check the change phenomenon of the coating. Resistivity: The surface resistivity is measured by the four-probe method (GB / T 1410-2006).

[0034] Table 4 Test results of the coatings prepared from the products of Examples 9 and 10

[0035] It can be seen from the test results of the products of Examples 9 and 10 that the coating prepared from the modified carbon black in Example 3 is superior to the untreated carbon black in terms of appearance, adhesion, hardness, corrosion resistance and conductivity, and is especially suitable for applications in harsh environments that require antistatic and corrosion resistance.

[0036] It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

Claims

1. A preparation method of modified carbon black, characterized in that: Comprising the following steps: a. Under the protection of inert gas, add carbon black into NaOH solution with a pH value of 12 - 14 and twice the mass of the carbon black, add sodium ferrate with 0.1 - 0.3 times the mass of the carbon black, and then add deionized water with 0.05 - 0.1 times the total mass of the carbon black and sodium ferrate; react at 40 - 60 °C for 4 - 8 hours, and stir at a speed of 300 - 500 r / min simultaneously; b. After the reaction in step a is completed, add 0.1 M dilute hydrochloric acid to adjust the pH value to neutral to terminate the oxidation; then centrifuge to separate the carbon black and wash it with deionized water until there is no Fe 3+ ; then vacuum dry at a temperature of 60 - 80 °C and a vacuum degree of 40 - 60 kPa for 4 - 6 hours; c. Disperse the carbon black obtained after drying in step b in 1M HCl solution with 20 times the mass of the carbon black, and perform ultrasonic treatment for 30 minutes; then add aniline monomer under the condition of ice bath temperature control, the mass ratio of carbon black to aniline is 1:0.3 - 0.5, and then slowly drop ammonium persulfate with a molar ratio of 1:1 to aniline, and react for 12 - 24 hours; d. Filter the product obtained in step c by suction, wash the obtained solid with absolute ethanol until the filtrate is colorless, and vacuum dry at 60 °C and a vacuum degree of 40 - 60 kPa until constant weight to obtain modified carbon black.

2. The preparation method of the modified carbon black according to claim 1, characterized in that: The inert gas in step a is nitrogen or argon, and the carbon black is acetylene carbon black.

3. The preparation method of the modified carbon black according to claim 1, characterized in that: In step a, the pH value of the NaOH solution is 13, the addition amount of sodium ferrate is 0.2 times the mass of the carbon black, and the added mass of deionized water is 0.08 times the total mass of the carbon black and sodium ferrate in the solution; react at 50 °C and stir at a speed of 400 r / min for 6 hours.

4. The preparation method of the modified carbon black according to claim 1, wherein: The drying in step b is vacuum drying at 70 °C for 5 hours.

5. The preparation method of the modified carbon black according to claim 1, characterized in that: In step c, the mass ratio of carbon black to aniline is 1:0.4, and the reaction is for 18 hours.

6. A modified carbon black, characterized in that: The modified carbon black prepared by the preparation method of the modified carbon black according to claim 1.

7. Application of a modified carbon black, characterized in that: The application of the modified carbon black according to claim 6 in explosives, rubber, and coatings.

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