A production method of polar carbon black

Abstract

A production method of polar carbon black belongs to the technical field of carbon black production. Its characteristics are as follows: Natural gas and hot air enter the reaction furnace through the pipeline in the combustion section of the reaction furnace. After preheating, ethylene tar is symmetrically sprayed into the throat section of the reaction furnace through an oil gun, and the flow rate is 4300 kg / h to 4800 kg / h. Secondary air supply is carried out in the oxidation reaction section after the throat section of the reaction furnace: The reaction time in the quenching section of the reaction furnace is controlled to be 0.8 s to 1.0 s. The powdered carbon black is collected by a bag filter and obtained through granulation, drying, and screening. Through the design of the reaction device and process, the oxygen content on the surface of the carbon black is increased, and the polar functional groups are increased. The difficulty of the present invention lies in how to increase the oxygen content while ensuring that the carbon black is not excessively oxidized and lost. The present invention designs an oxidation treatment process for carbon black, which only further oxidizes the surface of the carbon black, increases the surface polarity, and does not reduce the yield.

Description

Technical Field

[0001] A production method of polar carbon black belongs to the technical field of carbon black production. Background Art

[0002] With the continuous development of the uses of carbon black, new requirements are put forward for the performance of carbon black. When carbon black is applied to different materials, it is required to have different polarities. The surface oxygen content of carbon black produced by the oil furnace method is low, containing trace oxygen-containing groups, and the surface shows non-polarity. When mixed with polar polymer materials, uneven dispersion will occur. For example, in some water-based paints and coatings, coarsening will occur, affecting the use of products; in polar resins, poor dispersion will occur, resulting in a rough surface of the product and defects.

[0003] At present in China, strong acids, polyhydric alcohols, dispersants, etc. are used to modify the surface of carbon black to improve the surface polarity of carbon black. However, when carbon black is modified by this method, other impurities will be introduced, reducing the purity of carbon black. The purpose of the present invention is to provide a production method that can increase the polar groups on the surface of carbon black without adding any reagents, making the surface of carbon black show polarity and meeting the requirements of different uses. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: to overcome the deficiencies of the prior art and provide a production method of polar carbon black without adding any reagents.

[0005] The technical solution adopted by the present invention to solve its technical problems is: the production method of the polar carbon black is characterized in that the preparation steps are as follows:

[0006] 1) Natural gas and hot air enter the reaction furnace through the pipeline in the combustion section of the reaction furnace. The flow rate of natural gas is controlled at 1000 Nm 3 / h to 1200 Nm 3 / h; the flow rate of hot air is controlled at 15000 Nm 3 / h to 16000 Nm 3 / h, and the reaction temperature is controlled at 1850 °C to 1950 °C;

[0007] After sedimentation and filtration, the ethylene tar is preheated and symmetrically sprayed into the throat section of the reaction furnace through an oil gun, and the flow rate is 4300 kg / h to 4800 kg / h;

[0008] 2) Secondary air supply is carried out in the oxidation reaction section after the throat section of the reaction furnace: the flow rate of the introduced hot air is controlled at 5000 Nm 3 / h to 7000 Nm 3 / h;

[0009] 3) Control the reaction time in the quench section of the reaction furnace to be 0.8 s to 1.0 s; collect the powdered carbon black, and then obtain the product through granulation, drying, and screening.

[0010] Through the design of the reaction device and process, the present invention increases the oxygen content on the surface of carbon black and the number of polar functional groups. The difficulty of the present invention lies in how to increase the oxygen content while ensuring that the carbon black is not excessively oxidized and lost. The present invention designs an oxidation treatment process for carbon black, which only further oxidizes the surface of carbon black, increases the surface polarity while not reducing the yield.

[0011] Preferably, in the production method of the above-mentioned polar carbon black, the toluene insoluble matter in the vinyl tar described in step 1) is ≤1.0%, and the density ρ20 is 1.0 g / cm 3 ~1.1 g / cm 3 , the viscosity E80 ≤ 5.0, the moisture content ≤ 0.5%, and the ash content ≤ 0.05%; the initial boiling point is 210 °C, and the fraction before 360 °C is ≥ 70%. The vinyl tar with preferred indexes can better adapt to the device and process of the present invention, and can maintain a higher yield while ensuring an increase in the oxygen content on the surface of carbon black.

[0012] Preferably, in the production method of the above-mentioned polar carbon black, the sedimentation and filtration in step 1) are to place the raw material oil vinyl tar in a process storage tank and let it stand for more than 48 hours, so that the oil slag and impurities settle and separate and then are filtered through a basket filter; the mesh number of the filter screen of the basket filter is 80 meshes. Removing oil slag and impurities through natural sedimentation and simple filtration can avoid insufficient carbonization of large particles while retaining more useful components, which helps more components to be converted into the oxygen content on the surface of carbon black.

[0013] Preferably, in the production method of the above-mentioned polar carbon black, the diameter of the throat section of the reaction furnace is 550 mm to 600 mm; there are 6 oil guns radially symmetrically distributed in the throat section, the gun head angle of the oil gun is 90 to 120 degrees, and the injection pressure is controlled at 2 MPa to 3 MPa. The diameter of the throat section is designed to be 550 mm to 600 mm to adjust the flow rate of the incoming gas in the combustion section to make the raw material oil react fully; there are 6 symmetrically distributed raw material oil nozzles radially in the throat section, which are injected through a specific pressure and angle to control the degree of reaction and ensure full reaction.

[0014] Preferably, in the production method of the above-mentioned polar carbon black, the length of the quench section of the reaction furnace is 10 to 12 meters, and the quench water gun is 14.5 to 15.5 meters away from the oxidation reaction section of the reaction furnace. The function of the quench section is to terminate the reaction. The length of the quench section is designed to be 10 to 12 meters to adjust the reaction time, so as to further oxidize the surface of carbon black and increase the oxygen-containing groups on the surface of carbon black.

[0015] Preferably, in one of the above production methods of polar carbon black, an air preheater is connected to the carbon black flue gas outlet in the quenching section of the reaction furnace, and the hot air in step 1) and step 2) is obtained by heating with the air preheater. The air preheater uses the carbon black flue gas as a heat source to heat the air to an appropriate temperature without an additional heat source.

[0016] Preferably, in one of the above production methods of polar carbon black, the temperature of the hot air in step 1) and step 2) is 850 °C to 900 °C. The preferred hot air temperature is to better maintain the reaction temperature and thus control the carbonization degree of ethylene tar.

[0017] Preferably, in one of the above production methods of polar carbon black, the flow rate ratio of the natural gas to the hot air in step 1) is 1:14 to 15. The preferred flow rate ratio of natural gas to hot air is also to better maintain the reaction temperature and thus control the carbonization degree of ethylene tar.

[0018] Preferably, in one of the above production methods of polar carbon black, the temperature for preheating the ethylene tar is 180 °C to 200 °C. After preheating the ethylene tar to this temperature, an appropriate amount of small molecule components are gasified, bubbles appear inside the tar, and when sprayed into the throat section, the small molecule gasified components flash explosively, which helps to disperse the ethylene tar and instantaneously carbonize at high temperature. The particle size distribution of the obtained carbon black is more uniform; the carbonization is more complete and the oxygen element on the surface is more.

[0019] Preferably, in one of the above production methods of polar carbon black, the pH of the obtained carbon black is 3 to 5, and the oxygen element content on the carbon black surface is 8.49% to 9.0%. The polar carbon black obtained by the present invention has high compatibility with polar solvents, is evenly mixed with polar polymer materials, and has a wider application.

[0020] Compared with the prior art, the beneficial effects of the production method of a polar carbon black of the present invention are as follows: The design of the secondary air supply reaction furnace of the present invention designs hot air pipes at the front and rear of the reaction furnace respectively. The hot air at the front provides the oxygen required for combustion, and the hot air at the rear reacts with the carbon black flue gas to oxidize the carbon black surface and increase the oxygen-containing groups. The present invention designs the length of the quenching section, extends the reaction time, ensures sufficient reaction time, further oxidizes the carbon black surface, and can also increase the oxygen-containing groups on the carbon black surface. The carbon black produced by the method of the present invention has a pH of 3 to 5, and the oxygen element content on the carbon black surface is 8.49% to 9.0%. The polar carbon black obtained by the present invention has high compatibility with polar solvents, is evenly mixed with polar polymer materials, and has a wider application. Description of the Drawings

[0021] The technical solution of the present invention will be further described in detail below in conjunction with the drawings and embodiments. However, it should be noted that these drawings are only designed for the purpose of explanation and therefore do not limit the scope of the present invention. In addition, unless otherwise specified, these drawings are only intended to conceptually illustrate the structural configurations described herein and are not necessarily drawn to scale.

[0022] Figure 1 It is a process flow chart of a production method of a polar carbon black of the present invention.

[0023] Figure 2 It is the XPS elemental analysis result of a conventional carbon black.

[0024] Figure 3 It is the XPS elemental analysis result of another conventional carbon black.

[0025] Figure 4 It is the XPS elemental analysis result of the carbon black obtained in Example 2.

[0026] Figure 5 It is the XPS elemental analysis result of the carbon black obtained in Example 4. Specific Embodiments

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0028] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The ethylene tar used in each embodiment is purchased in the same batch. The toluene insoluble matter in the ethylene tar is detected to be 0.6%, the density ρ20 is 1.076 g / cm 3 , the viscosity E80 is 3.4, the moisture content is 0.36%, and the ash content is 0.02%; the initial boiling point is 210 °C, and the fraction before 360 °C is 79.3%. Before the experiment, the ethylene tar is stored statically in the process storage tank for 48 h and filtered through an 80-mesh basket filter.

[0029] Example 1

[0030] 1) Natural gas and hot air preheated to 880 °C enter the reaction furnace through the pipeline in the combustion section of the reaction furnace. The flow rate of natural gas is controlled at 1100 Nm 3 / h; The flow rate of hot air is controlled at 15500 Nm 3 / h, and the reaction temperature is controlled at 1900 °C;

[0031] After preheating the ethylene tar to 190 °C, it is symmetrically sprayed into the throat section of the reaction furnace through oil guns. The diameter of the throat section of the reaction furnace is 600 mm; There are 6 oil guns radially symmetrically distributed in the throat section. The gun head angle of the oil gun is 100 degrees, the injection pressure is controlled at 2.5 MPa, and the flow rate is 4500 kg / h.

[0032] 2) Secondary air supply is carried out in the oxidation reaction section after the throat section of the reaction furnace: The flow rate of the hot air at 880 °C is controlled at 6000 Nm 3 / h.

[0033] 3) The length of the quench section of the reaction furnace is 12 meters, and the quench water gun is 15 meters away from the oxidation reaction section of the reaction furnace; Control the reaction time of the quench section of the reaction furnace to be 0.9 s; The carbon black flue gas outlet of the quench section is connected with an air preheater to prepare the above-mentioned hot air; The powdered carbon black is collected by a bag filter and processed through granulation, drying, and screening to obtain the polar carbon black in this example; The pH of the obtained carbon black is 3, and the oxygen element content on the surface of the carbon black is 8.97%.

[0034] Example 2

[0035] 1) Natural gas and hot air preheated to 880 °C enter the reaction furnace through the pipeline in the combustion section of the reaction furnace. The flow rate of natural gas is controlled at 1000 Nm 3 / h; The flow rate of hot air is controlled at 15000 Nm 3 / h, and the reaction temperature is controlled at 1850 °C;

[0036] After preheating the ethylene tar to 190 °C, it is symmetrically sprayed into the throat section of the reaction furnace through oil guns. The diameter of the throat section of the reaction furnace is 600 mm; There are 6 oil guns radially symmetrically distributed in the throat section. The gun head angle of the oil gun is 100 degrees, the injection pressure is controlled at 2.5 MPa, and the flow rate is 4500 kg / h.

[0037] 2) Secondary air supply is carried out in the oxidation reaction section after the throat section of the reaction furnace: The flow rate of the hot air at 880 °C is controlled at 5000 Nm 3 / h to 7000 Nm 3 / h.

[0038] 3) The length of the quench section of the reaction furnace is 12 meters, and the quench water gun is 15 meters away from the oxidation reaction section of the reaction furnace; Control the reaction time of the quench section of the reaction furnace to be 0.9 s; The carbon black flue gas outlet of the quench section is connected with an air preheater to prepare the above-mentioned hot air; The powdered carbon black is collected by a bag filter and processed through granulation, drying, and screening to obtain the polar carbon black in this example; The pH of the obtained carbon black is 3, and the oxygen element content on the surface of the carbon black is 8.85%.

[0039] Example 3

[0040] 1) Natural gas and hot air preheated to 880 °C enter the reaction furnace through the pipeline in the combustion section of the reaction furnace. The flow rate of natural gas is controlled at 1150 Nm 3 / h; the flow rate of hot air is controlled at 16000 Nm 3 / h, and the reaction temperature is controlled at 1950 °C;

[0041] After being preheated to 190 °C, ethylene tar is symmetrically sprayed into the throat section of the reaction furnace through an oil gun. The diameter of the throat section of the reaction furnace is 600 mm; there are 6 oil guns symmetrically distributed radially in the throat section. The gun head angle of the oil gun is 100 degrees, the injection pressure is controlled at 2.5 MPa, and the flow rate is 4600 kg / h.

[0042] 2) Secondary air supplementation is carried out in the oxidation reaction section after the throat section of the reaction furnace: the flow rate of the hot air introduced is controlled at 5000 Nm 3 / h to 7000 Nm 3 / h.

[0043] 3) The length of the quenching section of the reaction furnace is 10 - 12 meters, and the quenching water gun is 14.5 - 15.5 meters away from the oxidation reaction section of the reaction furnace; the reaction time of the quenching section of the reaction furnace is controlled at 0.8 s - 1.0 s; the outlet of the carbon black flue gas in the quenching section is connected to an air preheater to prepare the above-mentioned hot air; a bag filter is used to collect powdered carbon black, and the polar carbon black of this example is obtained through granulation, drying, and screening; the pH of the obtained carbon black is 3, and the oxygen element content on the surface of the carbon black is 8.82%.

[0044] Example 4

[0045] 1) Natural gas and hot air preheated to 850 °C enter the reaction furnace through the pipeline in the combustion section of the reaction furnace. The flow rate of natural gas is controlled at 1000 Nm 3 / h; the flow rate of hot air is controlled at 15000 Nm 3 / h, and the reaction temperature is controlled at 1850 °C;

[0046] After being preheated to 180 °C, ethylene tar is symmetrically sprayed into the throat section of the reaction furnace through an oil gun. The diameter of the throat section of the reaction furnace is 550 mm; there are 6 oil guns symmetrically distributed radially in the throat section. The gun head angle of the oil gun is 90 degrees, the injection pressure is controlled at 2 MPa, and the flow rate is 4300 kg / h.

[0047] 2) Secondary air supplementation is carried out in the oxidation reaction section after the throat section of the reaction furnace: the flow rate of the hot air at 850 °C introduced is controlled at 5000 Nm 3 / h.

[0048] 3) The length of the quench section of the reactor is 10 m, and the quench water lance is 14.5 m away from the oxidation reaction section of the reactor; the reaction time in the quench section of the reactor is controlled at 0.8 s; the outlet of the carbon black flue gas in the quench section is connected to an air preheater to prepare the above-mentioned hot air; a bag filter is used to collect the powdered carbon black, and the polar carbon black of this example is obtained through granulation, drying, and screening; the pH of the obtained carbon black is 3, and the oxygen element content on the surface of the carbon black is 8.49%.

[0049] Example 5

[0050] 1) Natural gas and hot air preheated to 900 °C enter the reactor through the pipeline in the combustion section of the reactor. The flow rate of natural gas is controlled at 1200 Nm 3 / h; the flow rate of hot air is controlled at 16000 Nm 3 / h, and the reaction temperature is controlled at 1950 °C;

[0051] The ethylene tar is preheated to 200 °C and then symmetrically sprayed into the throat section of the reactor through an oil gun. The diameter of the throat section of the reactor is 600 mm; there are 6 oil guns symmetrically distributed radially in the throat section, the gun head angle of the oil gun is 120 degrees, the injection pressure is controlled at 3 MPa, and the flow rate is 4800 kg / h.

[0052] 2) Secondary air supply is carried out in the oxidation reaction section after the throat section of the reactor: the flow rate of the hot air at 900 °C is controlled at 7000 Nm 3 / h.

[0053] 3) The length of the quench section of the reactor is 12 m, and the quench water lance is 15.5 m away from the oxidation reaction section of the reactor; the reaction time in the quench section of the reactor is controlled at 1.0 s; the outlet of the carbon black flue gas in the quench section is connected to an air preheater to prepare the above-mentioned hot air; a bag filter is used to collect the powdered carbon black, and the polar carbon black of this example is obtained through granulation, drying, and screening; the pH of the obtained carbon black is 3, and the oxygen element content on the surface of the carbon black is 8.57.

[0054] Example 6

[0055] 1) Natural gas and hot air preheated to 880 °C enter the reactor through the pipeline in the combustion section of the reactor. The flow rate of natural gas is controlled at 1100 Nm 3 / h; the flow rate of hot air is controlled at 15500 Nm 3 / h, and the reaction temperature is controlled at 1900 °C;

[0056] The ethylene tar is preheated to 240 °C and then symmetrically sprayed into the throat section of the reactor through an oil gun. The diameter of the throat section of the reactor is 600 mm; there are 6 oil guns symmetrically distributed radially in the throat section, the gun head angle of the oil gun is 100 degrees, the injection pressure is controlled at 2.5 MPa, and the flow rate is 4500 kg / h.

[0057] 2) Secondary air supplementation is carried out in the oxidation reaction section after the reaction furnace throat section: the flow rate of the hot air at 880 °C is controlled at 6000 Nm 3 / h.

[0058] 3) The length of the rapid cooling section of the reaction furnace is 12 meters, and the rapid cooling water gun is 15 meters away from the oxidation reaction section of the reaction furnace; the reaction time of the rapid cooling section of the reaction furnace is controlled at 0.9 s; the outlet of the carbon black flue gas in the rapid cooling section is connected with an air preheater to prepare the above-mentioned hot air; the powdered carbon black is collected by a bag filter and is granulated, dried and screened to obtain the polar carbon black of this example; the pH of the obtained carbon black is 3.5, and the oxygen element content on the surface of the carbon black is 8.87%.

[0059] Example 7

[0060] 1) Natural gas and hot air preheated to 880 °C enter the reaction furnace through the pipeline in the combustion section of the reaction furnace. The flow rate of natural gas is controlled at 1100 Nm 3 / h; the flow rate of hot air is controlled at 15500 Nm 3 / h, and the reaction temperature is controlled at 1900 °C;

[0061] The ethylene tar is preheated to 190 °C and then symmetrically sprayed into the throat section of the reaction furnace through an oil gun. The diameter of the throat section of the reaction furnace is 500 mm; there are 6 oil guns radially symmetrically distributed in the throat section, the gun head angle of the oil gun is 100 degrees, the spraying pressure is controlled at 2.5 MPa, and the flow rate is 4500 kg / h.

[0062] 2) Secondary air supplementation is carried out in the oxidation reaction section after the reaction furnace throat section: the flow rate of the hot air at 880 °C is controlled at 6000 Nm 3 / h.

[0063] 3) The length of the rapid cooling section of the reaction furnace is 12 meters, and the rapid cooling water gun is 15 meters away from the oxidation reaction section of the reaction furnace; the reaction time of the rapid cooling section of the reaction furnace is controlled at 0.9 s; the outlet of the carbon black flue gas in the rapid cooling section is connected with an air preheater to prepare the above-mentioned hot air; the powdered carbon black is collected by a bag filter and is granulated, dried and screened to obtain the polar carbon black of this example; the pH of the obtained carbon black is 4, and the oxygen element content on the surface of the carbon black is 8.12%.

[0064] Example 8

[0065] 1) Natural gas and hot air preheated to 880 °C enter the reaction furnace through the pipeline in the combustion section of the reaction furnace. The flow rate of natural gas is controlled at 1100 Nm 3 / h; the flow rate of hot air is controlled at 15500 Nm 3 / h, and the reaction temperature is controlled at 1900 °C;

[0066] The ethylene tar is preheated to 190°C and then symmetrically sprayed into the throat section of the reaction furnace through an oil gun. The diameter of the throat section of the reaction furnace is 600 mm. Six oil guns are radially symmetrically distributed in the throat section. The gun head angle of the oil gun is 100 degrees. The spraying pressure is controlled at 2.5 MPa and the flow rate is 4500 kg / h.

[0067] 2) Secondary air supply is carried out in the oxidation reaction section after the throat section of the reaction furnace: The flow rate of the hot air at 880°C is controlled at 6000 Nm 3 / h.

[0068] 3) The length of the quenching section of the reaction furnace is 8 meters. The quenching water gun is 11 meters away from the oxidation reaction section of the reaction furnace. The reaction time of the quenching section of the reaction furnace is controlled at 0.6 s. An air preheater is connected to the outlet of the carbon black flue gas in the quenching section to prepare the above-mentioned hot air. The powdered carbon black is collected by a bag filter and processed through granulation, drying, and screening to obtain the polar carbon black of this example. The pH of the obtained carbon black is 3, and the oxygen element content on the surface of the carbon black is 7.33%.

[0069] The comparison of the oxygen element content on the surface of Example 2, 4 and conventional carbon black tested by XPS is shown in Table 1.

[0070] Table 1 [[ID=!15]]

[0071]

[0072]

[0073] As described above, it is only the preferred embodiment of the present invention, and it is not a limitation to the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims

1. A method for producing polar carbon black, characterized in that: The preparation steps are: 1) Natural gas and hot air enter the reactor through the pipeline of the combustion section of the reactor. The natural gas flow rate is controlled at 1000Nm 3 / h~1200Nm 3 / h; hot air flow is controlled at 15000Nm 3 / h~16000Nm 3 / h, the reaction temperature is controlled at 1850℃~1950℃; The ethylene tar after sedimentation and filtration is preheated to 180℃~200℃, and then sprayed symmetrically into the throat section of the reactor through an oil gun at a flow rate of 4300kg / h~4800kg / h; 2) Secondary air supply is carried out in the oxidation reaction section after the throat section of the reactor: the flow rate of hot air is controlled at 5000Nm 3 / h~7000Nm 3 / h; 3) Control the reaction time of the rapid cooling section of the reactor to 0.8s to 1.0s; collect the powdered carbon black, and then granulate, dry and screen it; The diameter of the reactor throat section is 550mm to 600mm; six oil guns are radially symmetrically distributed in the throat section, the gun head angle is 90 to 120 degrees, and the injection pressure is controlled at 2MPa to 3MPa; The length of the quenching section of the reactor is 10 to 12 meters, and the quenching water gun is 14.5 to 15.5 meters away from the oxidation reaction section of the reactor; The temperature of the hot air in step 1) and step 2) is 850°C to 900°C.

2. The method for producing polar carbon black according to claim 1, wherein: The toluene insoluble matter in the ethylene tar described in step 1) is ≤1.0%, and the density ρ20 is 1.0 g / cm 3 ~1.1g / cm 3 , viscosity E80≤5.0, moisture ≤0.5%, ash ≤0.05%; the initial distillation point is 210℃, and the distillation before 360℃ is ≥70%.

3. The method for producing polar carbon black according to claim 1, wherein: The sedimentation and filtration in step 1) are as follows: the raw material oil ethylene tar is put into a process storage tank and stored for more than 48 hours to allow the oil residue and impurities to settle and separate, and then filtered through a basket filter; the mesh size of the basket filter is 80 mesh.

4. The method for producing polar carbon black according to claim 1, wherein: The carbon black fume outlet of the rapid cooling section of the reactor is connected to an air preheater, and the hot air in step 1) and step 2) is heated by the air preheater.

5. The method for producing polar carbon black according to claim 1, wherein: The flow ratio of natural gas to hot air in step 1) is 1:14-15.

6. The method for producing polar carbon black according to claim 1, wherein: The pH value of the obtained carbon black is 3-5, and the oxygen content on the surface of the carbon black is 8.49%-9.0%.

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