JPH10140033A - Production of carbon black - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing carbon black satisfying both high blackness and good dispersibility, small in primary particle size, also small in its agglomerate size and narrow in agglomerate size distribution with minute amounts of relatively large-sized agglomerates. SOLUTION: This carbon black production method uses a production oven having a 1st reaction zone where a high-temperature combustion gas flow is formed, a 2nd reaction zone equipped with a choke unit and to produce the aimed carbon black by mixing a stock hydrocarbon with the above gas flow, and a 3rd reaction zone situated on the downstream side of the 2nd reaction zone and to terminate the reaction. In this case, the oxygen concentration in the combustion gas at a site through which the stock carbon black is introduced is set at <=3vol.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of carbon black used for various uses such as a filling material, a reinforcing material, a conductive material and a coloring pigment, and to an effective production method for controlling the physical properties thereof. is there.

[0002]

2. Description of the Related Art Carbon black is widely used as a pigment, a filler, a reinforcing pigment, and a weather resistance improver. Generally, carbon black is produced in a first reaction zone of a cylindrical carbon black production furnace in a furnace axial direction. Alternatively, the oxygen-containing gas and the fuel are introduced in a tangential direction, and the high-temperature combustion gas stream obtained by the combustion is successively moved to a second reaction zone installed in the furnace axis direction, and is introduced into the gas stream. A furnace type production method in which a raw material hydrocarbon is introduced to generate carbon black and the reaction gas is rapidly cooled in a third reaction zone to stop the reaction is widely known.

[0003] Carbon black used as a colorant in resin colorants, printing inks and paints is required to have excellent blackness, dispersibility, gloss and coloring power, and is mainly used as a reinforcing agent for automobile tires. The carbon black to be used is required to have excellent wear resistance. Blackness and tinting strength depend greatly on the primary particle size of carbon black,
It is known that the smaller the primary particle diameter, the higher the blackness. For example, the relationship between blackness and primary particle size is disclosed in
-68992. It is also known that carbon black having such a small particle diameter exhibits a high degree of wear resistance when used as a tire reinforcing agent.

In order to obtain carbon black having a small particle diameter, first, a raw material hydrocarbon is sprayed into a high-speed gas stream in a choke section provided in a second reaction zone, and the kinetic and thermal energy of the gas are used as a liquid feedstock. It is well known that it is effective to use for atomizing. It is also known that carbon black having a small particle diameter can be obtained by reducing the amount of the base oil to be injected with respect to the amount of the combustion gas. However, if the injection ratio of the base oil is reduced, the productivity of carbon black decreases. It is also well known that increasing the gas temperature in the feedstock injection region is effective for efficiently producing carbon black having a small particle diameter as a method of not reducing the productivity. In this regard, in the production of furnace black, it has been generally performed to raise the temperature of the carbon black producing region by leaving a certain amount of residual oxygen in the gas at the feedstock injection portion and partially burning the feedstock itself. . However, in this method, a part of the injected base oil is not used as carbon black but is used in a combustion reaction, so that the yield is deteriorated.

On the other hand, the distribution of the primary particle diameter also has a significant effect on the rubber properties, particularly on the tire tread rubber composition which requires high abrasion resistance, and it is said that the narrower the primary particle diameter distribution is, the better. . In general, the smaller the average particle size, the narrower the distribution. However, a method for narrowing the primary particle size distribution is also disclosed. For example, JP-A-3-3316
Japanese Patent Application Publication No. 7-27139 discloses a so-called "back-mixing" of a vortex generated at an outlet enlarged portion of a choke portion by making the length of the choke sufficient to allow the carbon black formation reaction to be substantially completed. There is disclosed a method of obtaining carbon black having a relatively narrow particle size distribution by a method that does not exert an influence during the carbon black production reaction.

[0006] Aggregates are factors that affect the properties of carbon black as well as the primary particle size. The size of the agglomerates greatly affects the tensile stress and extrusion characteristics when compounded with rubber, the dispersibility, blackness and viscosity when compounded with ink and paint vehicles and resins. Carbon black is ultimately composed of aggregates of many primary particles, and controlling the size and shape of these aggregates leads to controlling the properties of carbon black itself, It is more important than controlling the primary particle size.

Regarding the effect of aggregates, the size and distribution of the aggregates are quantified by regarding the aggregates as simple particles. By treating the aggregates as particles, various particle diameter measurement techniques can be applied, and the size of the aggregate measured in this way is expressed as the aggregate diameter. Aggregates have a significant effect on the properties of carbon black, and it has become clear that many of the properties of carbon black, previously thought to be due to primary particle size, can be better explained by the aggregate size. Have been. For example, it is considered that the diameter of the aggregate plays a large role in optical properties such as coloring power and dynamic viscoelastic properties and reinforcing properties of the compounded rubber composition. It is known that the smaller the agglomerate diameter, the higher the degree of blackness when viewed in resin coloring applications.

In general, as a method of reducing the diameter of the aggregate, an alkali metal salt or a solution thereof is added to a raw material oil or introduced into a combustion zone or a reaction zone.
However, when incorporated into vehicles and resins of inks and coatings, the reduction in particle size and the size of aggregates cause deterioration in dispersibility and fluidity. Therefore, regarding the relationship between the characteristics of carbon black and the physical properties of the resin, it is important how to satisfy blackness and dispersibility, which are generally in a trade-off relationship.

Another problem is to produce such carbon black efficiently.

[0010]

SUMMARY OF THE INVENTION The present invention provides a method for efficiently producing carbon black satisfying both high blackness and good dispersibility. The present invention provides a production method for efficiently obtaining carbon black having a small primary particle diameter, a small aggregate diameter, a small aggregate distribution width, and a small large aggregate diameter.

[0011]

Means for Solving the Problems The present inventors have analyzed the dispersion behavior of carbon black in a matrix and the factors affecting blackness, and have found that higher blackness and better dispersibility can be obtained as compared with the prior art. As a result of various studies to obtain carbon black having, it was found that fine aggregates had an adverse effect on dispersion, large aggregates had an adverse effect on blackness, and therefore uniform aggregates without fine aggregates and large aggregates were obtained. Having carbon black,
They were found to have high blackness and good dispersibility. In other words, small particle diameter, carbon black in which the distribution of the aggregate diameter is sharp and the large aggregate diameter does not exist in the small aggregate diameter, and the dispersibility is high and the blackness is good, that is, the two-dimensional relationship described above is satisfied. It was discovered that it would solve the problem of blackness and dispersibility that had been considered. Further, as a result of further intensive studies on efficient conditions for obtaining carbon black having such excellent characteristics, the above-described excellent characteristics were obtained by setting the position where the raw material hydrocarbon was introduced to specific conditions. It has been found that carbon black can be efficiently produced. Surprisingly, by reducing the oxygen concentration at the feed hydrocarbon introduction position as much as possible, carbon black having such a small particle diameter, a small aggregate diameter, and a large particle diameter is suppressed. They found that they could get good yields. That is, the present invention provides a first reaction zone for forming a high-temperature combustion gas stream, and a second reaction zone having a choke portion for mixing a raw material hydrocarbon with the obtained high-temperature combustion gas stream to produce carbon black. A method for producing carbon black using a production furnace having a third reaction zone downstream of a second reaction zone and having a third reaction zone for stopping the reaction, wherein the oxygen concentration in the combustion gas at the site where the raw material hydrocarbon is introduced is 3 vol% or less. And a method for producing carbon black.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The present invention relates to a so-called furnace method for obtaining carbon black by introducing a raw material hydrocarbon in a production furnace having a first reaction zone, a second reaction zone, and a third reaction zone.

The configuration of the present invention will be described with reference to the drawings. FIG. 1 is a schematic vertical sectional view of a main part showing an example of a carbon black production furnace that can be used in the present invention. The furnace has a first reaction zone 1 in the longitudinal direction for forming a hot combustion gas stream;
A second reaction zone 2 having a choke portion (having a choke portion 4) for mixing the resulting high-temperature combustion gas stream with a raw material hydrocarbon to form carbon black, and a downstream portion following the second reaction zone. , And a third reaction zone 3 for stopping the reaction. The process itself in each reaction zone can basically adopt the same method as in the prior art.

In the first reaction zone, fuel hydrocarbons and an oxygen-containing gas are generally introduced from the combustion nozzle 5 to generate a high-temperature gas stream. As the oxygen-containing gas, air, oxygen or a mixture thereof is generally used. As the fuel hydrocarbon, hydrogen, carbon monoxide, natural gas, petroleum gas and petroleum-based liquid fuels such as heavy oil, coal-based fuels such as creosote oil are generally used. Liquid fuel is used.

In the second reaction zone, the raw hydrocarbon is spray-injected from a raw hydrocarbon introduction nozzle 6 provided in parallel or in the horizontal direction with the high temperature gas flow obtained in the first reaction zone, and the raw hydrocarbon is thermally decomposed. To convert it to carbon black. As raw material hydrocarbons, generally, benzene, toluene, xylene,
Aromatic hydrocarbons such as naphthalene and anthracene; coal-based hydrocarbons such as creosote oil and carboxylic acid oil; heavy oils such as ethylene heavy-end oil and FCC oil;
Acetylene unsaturated hydrocarbons, ethylene hydrocarbons, and aliphatic saturated hydrocarbons such as pentane and hexane are preferably used.

In the third reaction zone, the high-temperature reaction gas is
A liquid or gaseous cooling medium such as water is sprayed from the reaction stopping fluid introduction nozzle 7 to cool the mixture to 800 ° C. or less. The cooled carbon black can be subjected to a known general process such as separation and recovery from gas by a collecting bag filter or the like. In the figure, reference numeral 8 denotes a control valve.

Here, the present invention is characterized in that the oxygen concentration at the feed hydrocarbon introduction position is 3 vol% or less. Preferably, it is 0.05 to 1 vol%. As a result, the obtained carbon black has a small aggregate size, the aggregate distribution is extremely sharp, the generation of aggregates having a large particle size is suppressed, and a small particle size can be obtained with good yield. The inventors have found.

Conventionally, furnace black obtained by the furnace method has been considered to be produced by partial combustion of the raw material hydrocarbon, so that the residual oxygen concentration in the combustion gas at the raw material hydrocarbon introduction site is set to about 5 to 10 vol%, The feedstock was partially burned. The inventors have surprisingly found that by suppressing the oxygen concentration to a very small amount, the aggregate distribution is sharp, there is no aggregate having a large particle diameter, and further, the carbon black having a small aggregate diameter and a small particle diameter is increased. They found what they could get at a yield.

It is not completely clear why the above-mentioned effects of the present invention can be achieved by suppressing the oxygen concentration at the starting hydrocarbon introduction site to a low level. As a result of conducting experiments in which the oxygen concentration was varied, it was found that the lower the oxygen concentration, the lower the final CO concentration in the exhaust gas. Decreasing the CO concentration means that the rate of generation of CO _{2 in} the combustion reaction is increasing, and that the calorific value in the combustion reaction is increasing and the combustion gas is being heated to a higher temperature. Conceivable. The reaction when the excess oxygen becomes CO ₂ is expressed by C + O ₂ → CO ₂ , and the reaction when the excess oxygen becomes CO is expressed by 2C + O ₂ → 2CO. Consumes carbon. Therefore, it is presumed that the generated CO is reduced due to the low oxygen concentration in the raw material hydrocarbon introduction site, so that carbon black having a small particle diameter can be obtained, and the yield has been greatly improved.

Further, since the oxygen concentration in the feed hydrocarbon introduction site is low, the partial combustion of the feed hydrocarbon is small, and the atmosphere in the region where carbon black is generated is kept uniform, so that the aggregate diameter distribution is sharp. It is presumed that a suitable carbon black can be obtained. To measure the oxygen concentration at the raw hydrocarbon introduction site, collect the gas at the raw hydrocarbon introduction site and measure nitrogen, oxygen, carbon dioxide, carbon monoxide, hydrogen, methane, and acetylene, for example, with a gas chromatography measurement device. Can be obtained by Water generated by combustion is not included in the calculation.

The temperature at the site where the raw hydrocarbon is introduced is 18
The temperature is preferably at least 00 ° C, more preferably at least 1900 ° C, even more preferably at 2000 to 2400 ° C. Thereby, carbon black having a small particle diameter, a small aggregate diameter, and a sharp aggregate distribution can be easily obtained. Carbon black agglomerates, after the raw material hydrocarbons thermally decompose, condensed, fused to droplets, a nucleus precursor is formed, primary particles are generated, and then through mutual collision of particles,
It is considered to be formed by fusion carbonization. This reaction proceeds faster at higher temperatures, and the primary particles produced are also smaller. Also,
It is considered that since the carbonization rate is increased, the time required for the primary particles to collide with each other to form an aggregate and to be shortened is also reduced, so that the aggregate is also reduced. Therefore, the temperature at the site where the raw material hydrocarbon is introduced is desirably sufficiently high for the raw material hydrocarbon to be uniformly vaporized and thermally decomposed, and further to obtain a small particle size carbon black. It is believed that a temperature range is preferred.

In order to set the temperature of the site for introducing the raw material hydrocarbon to the above range, oxygen can be added to air, for example, when forming a high-temperature combustion gas stream in the first reaction zone. Of course, the method of increasing the temperature of the combustion gas is not limited to the addition of oxygen, but it is also possible to adopt a method such as preheating air. The temperature in the furnace can be confirmed by means such as a radiation thermometer.

In the present invention, the second reaction zone has a choke portion. The chalk portion is a portion where the cross-sectional area is sharply reduced. In the present invention, the choke portion is 800 mm or more, preferably 800 to 3000 mm.
It is particularly desirable that The present inventors have found that particularly in this range, the aggregate diameter of the obtained carbon black can be particularly reduced.

It has been found by the present inventors that the region where the aggregates are formed desirably does not have a high disturbance field due to a change in the flow path of the throttle or the like. It has also been found that control of the distribution of aggregates requires longer time control than control of the particle size distribution. For this reason, since the choke portion has a certain length, the condition of the reaction zone can be kept uniform until the primary particles and aggregates of carbon black are formed after the supply of the raw material hydrocarbon, and Since high disturbance due to a large change in the cross-sectional shape of the flow channel is suppressed until the reaction of generating primary particles and aggregates of carbon black after the supply of hydrogen is completed, the aggregate distribution is achieved by having the length of the choke portion. It is presumed that it contributes to the control of the size and is effective in preventing the formation of a large aggregate diameter.

Here, the inlet of the choke portion, which is the start portion of the choke portion, includes the narrowest portion of the flow path, and the angle with respect to the axial direction in which the flow path is reduced from 5 ° to 5 °.
The following are the parts that change. On the other hand, the outlet of the choke portion, which is the terminal of the choke portion, refers to a portion where the angle with respect to the axial direction in which the flow path is reduced has a value exceeding 5 °. The diameter of the chalk is preferably 170 mm or less. Particularly preferably 3
It is 0 to 170 mm, more preferably 50 to 150 mm. In this range, particularly those having a sharp aggregate distribution can be easily obtained.

The higher the gas flow rate in the choke, the better. After the feed hydrocarbon is introduced, it is atomized by the motion and heat energy of the combustion gas. The speed of the combustion gas at that time is preferably as high as possible, preferably 250 m / s or more, and 300 to 500 m / s.
m / s is preferred. In this range, carbon black having a small particle size, a small aggregate, and a narrow particle size distribution can be easily obtained.

In order to uniformly disperse the raw material hydrocarbons in the furnace, it is preferable to introduce the raw material hydrocarbons into the furnace from two or more nozzles. The feed position of the raw hydrocarbon is
It is preferable to set the range within 1 ms within the choke portion and on the basis of the cross-sectional average flow velocity of the combustion gas from the choke inlet. More preferably, it is within the range of 0.6 ms. By introducing at this site, carbon black having a particularly small particle diameter and a uniform aggregate diameter can be obtained.

According to the method for producing carbon black of the present invention described above, it is possible to obtain carbon black having a small aggregate, a sharp distribution, and a small particle diameter. Conventionally, cD has been used as an evaluation index for aggregates.
A centrifugal sedimentation method and an electron microscopic analysis in an aqueous dispersion of BP and carbon black are known. Recently, a centrifugal sedimentation method has been used to evaluate the size and distribution of aggregates.
In Examples of the present invention, as an indicator of the sharpness of the aggregate diameter, the maximum frequency Stokes equivalent diameter D _mod and the half-width D _{1 /} of the maximum frequency Stokes equivalent diameter in the aggregate Stokes equivalent diameter distribution by centrifugal sedimentation. ₂ ratio was evaluated using D ₇₅ as an indication that there is no large agglomerates diameter.

According to the production method of the present invention, an average particle diameter of 25
The ratio of the maximum frequency Stokes equivalent diameter D _mod to the half-width of the maximum frequency Stokes equivalent diameter, ie, D _1/2 / D _{mod, in the} aggregate Stokes equivalent diameter distribution by centrifugal sedimentation at or below nm.
Is not more than 0.6, and the ratio of volume 75% diameter to D _mod D ₇₅ / D
Carbon black having a _mod of 1.3 or less, a small particle diameter, a small aggregate diameter, a sharp aggregate diameter distribution, and a small number of large aggregate diameters can be efficiently obtained. Furthermore, PV
Carbon black having an average particle diameter of 20 nm or less, which is more preferable for increasing the C blackness, can be easily obtained.

According to the present invention, the particle size is 5 to 25 nm, further 8 to 17 nm, and the N ₂ SA is 100 to 700 m ² /
g, furthermore, 120 to 700 m ² / g, and cDBP is 40.
~ 110cc / 100g, furthermore 50 ~ 80cc /
g, D _mod is 10 to 70 nm, and further 20 to 50 n
m, D _1/2 is 10 to 50 nm, further 10 to 30 n
m, a carbon black having a PVC blackness of 3 to 35, more preferably 5 to 35, and a dispersion index of 1 to 200, furthermore 10 to 150 can be obtained.

[0031]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. (Examples 1 to 4) A first reaction zone having an inner diameter of 500 mm and a length of 1400 mm provided with an air introduction duct and a combustion burner as shown in FIG. 1 and connected to the first reaction zone, and a plurality of raw material nozzles are penetrated from the periphery. 60mm inside diameter, 800mm length
A second reaction zone having a choke portion, a third reaction zone having an inner diameter of 100 mm and a length of 6000 mm equipped with a quench device,
A carbon black production furnace having a structure in which control valves having an inner valve diameter of 80 mm were sequentially connected as a throttle mechanism was installed.

The position of the raw material nozzle is 100 mm from the entrance of the choke section. Using the above furnace, carbon black was produced under the conditions shown in Table 1. Creosote oil was used as fuel and raw hydrocarbon. In Examples 3 and 4, oxygen was added to air to increase the combustion gas temperature. In Table 1, "combustion gas temperature", "combustion gas oxygen concentration", and "furnace pressure" are those at the site where the raw material hydrocarbon is introduced. The “potassium concentration” defines the concentration of KOH added to the raw material hydrocarbon as the concentration of potassium.

Table 2 shows various properties of the obtained carbon black. The following test method was used to determine the analytical properties of the resulting carbon black. (Specific surface area) The specific surface area (N ₂ SA) is ASTM D30
37-88. (CDBP) Crushed DBP absorption number (cDBP) is ASTM
Determined according to D-3493-88. (D _mod , D _1/2 ) Maximum frequency Stokes equivalent diameter (D _mod )
The Stokes equivalent diameter _half width (D _1/2 ) was determined as follows.

Using a 20% ethanol solution as a spin solution, a Stokes equivalent diameter was measured by a centrifugal sedimentation type flow rate distribution measuring device (DCF3 type manufactured by JL Automation), and the Stokes equivalent diameter was measured relative to the given sample. A histogram of target occurrence frequency (FIG. 2) is created. A line (B) is drawn from the peak (A) of the histogram to the X axis in parallel with the Y axis and ends at a point (C) on the X axis of the histogram. The Stokes diameter at point (C) is the maximum frequency Stokes equivalent diameter D _mod . Further, the midpoint (F) of the obtained line (B) is determined, and a line (G) is drawn through the midpoint (F) and parallel to the X axis. The line (G) intersects the distribution curve of the histogram at two points D and E. The absolute value of the difference between the two Stokes diameters at two points D and E of the carbon black particles is the Stokes equivalent diameter _half width D1 _{/ 2} value. (D ₇₅ ) The volume 75% diameter (D ₇₅ ) was determined as follows.

In the above method of determining the maximum frequency Stokes diameter, a histogram of the Stokes equivalent diameter versus the relative frequency of occurrence of the sample The volume was obtained from each Stokes diameter and frequency from FIG. Make a graph showing the total volume of the sample. (FIG. 3) Thus, the middle point (A) in FIG. 3 represents the sum of the volumes of all the samples. Here, a point (B) having a value of 75% of the total volume is determined, and a line is drawn from the point (B) to the X axis until the curve intersects the equilibrium. A line is equilibrium drawn from the point (C) to the Y axis, and the value at the point (D) crossing the X axis is the volume 75% diameter (D ₇₅ ). (PVC Blackness) The PVC blackness is determined by adding the carbon black of the present invention to a PVC resin, dispersing and sheeting with two rolls, and using Mitsubishi Chemical Corporation carbon black “# 40”.
The blackness of “# 45” is defined as 1 point, 10 points and a reference value, respectively.
The blackness of the sample was evaluated by visual evaluation. (Dispersion index) The dispersion index was evaluated by the following method. LD
The state of dispersion in the PE resin was observed, and the number of undispersed aggregates was counted. The larger the number, that is, the larger the dispersion index, the worse the dispersibility.

LDP with 250cc Banbury mixer
E resin mixed with 40% by weight of sample carbon black
Knead at 5 ° C for 4 minutes. Mixing conditions LDPE resin 101.89 g Calcium stearate 1.39 g Irganox 1010 0.87 g Sample carbon black 69.43 g Next, the mixture is diluted with a two-roll mill at 120 ° C. so that the carbon black concentration becomes 1% by weight.

Diluting compound preparation conditions LDPE resin 58.3 g Calcium stearate 0.2 g Carbon black 40% blended resin 1.5 g A sheet with slit width 0.3 mm, cut into chips, and cut on a hot plate at 240 ° C. ± 3μm
Into a film. The diameter distribution of undispersed aggregates having a diameter of 0.2 mm or more in a 3.6 mm × 4.7 mm field of view is measured with an optical microscope having a magnification of 20 ×, and the total area is calculated. This area is calculated by dividing the total area by the reference area based on the area of the undispersed aggregate having a diameter of 0.35 mm as the number of reference particles. This is observed in 16 or more visual fields, and the average value is used as the dispersion index.

The productivity at the same particle size or the same PVC blackness is as follows:

It can be expressed as feedstock feedstock feedstock yield / air quantity, and the fuel consumption rate decreases as the total carbon yield increases. (Particle size) According to electron microscopy. Electron microscopy is a method described below. The carbon black is put into chloroform and irradiated with ultrasonic waves of 200 KHz for 20 minutes to disperse, and then the dispersion sample is fixed to the supporting film. This is photographed with a transmission electron microscope, and the particle diameter is calculated from the diameter on the photograph and the magnification of the photograph. This operation is performed about 1500 times, and the values are obtained by arithmetic averaging.

[0040]

[Table 1]

[0041]

[Table 2]

(Comparative Examples 1 and 2) Comparative Example 1 was carried out under the conditions shown in Table 1 using the carbon black production furnace used in the examples. Comparative Example 2 was carried out using a production furnace in which the length of the choke portion of the production furnace of the example was 500 mm. The physical properties of the obtained carbon black are shown in Table-2.

When the carbon black of the present invention obtained in the example was compared with that obtained in the comparative example, as shown in Table 2, the carbon black of the example was smaller than that of the comparative example. ing. Examples 1 and 2 and Comparative Example 2
In comparison, the particle diameters are the same, but in the example, the feedstock yield and the total carbon yield are significantly higher. Further, in Examples 1 and 2, D _1/2 / D _mod was small and the distribution of the aggregate diameter was sharp, D ₇₅ was small, and there were few large aggregate diameters as compared with Comparative Example 2. In addition, it exhibits high blackness, has a low dispersion index, and has good dispersibility.

[0044]

The carbon black obtained according to the present invention, when used as a black pigment in a resin colorant, printing ink or paint, satisfies the blackness and dispersibility which have been conventionally difficult and difficult. Meanwhile, productivity can be improved. Therefore, it is very useful as a black pigment in resin colorants, printing inks and paints.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of an essential part showing an example of a carbon black production furnace that can be used in the present invention.

FIG. 2 is a diagram showing a method of obtaining a maximum frequency Stokes equivalent diameter (D _mod ) and a Stokes equivalent diameter _half width (D _1/2 ).

FIG. 3 is a diagram showing a method for _{obtaining a} volume 75% diameter (D ₇₅ ).

[Explanation of symbols]

 1 First reaction zone 2 Second reaction zone 3 Third reaction zone

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeru Kawakami 1-1 Kurosaki Joishi, Yawatanishi-ku, Kitakyushu City, Fukuoka Prefecture Inside the Kurosaki Works of Mitsubishi Chemical Corporation (72) Inventor Yoshihiro Omae 1 Kurosaki Joishi, Yawata-Nishi-ku, Kitakyushu-shi, Fukuoka Prefecture No. 1 Mitsubishi Chemical Corporation Kurosaki Office (72) Inventor Hiroaki Takehara 1-1 Kurosaki Castle Stone, Yawata Nishi-ku, Kitakyushu-shi, Fukuoka Prefecture Mitsubishi Chemical Corporation Kurosaki Office

Claims (9)

[Claims] A first reaction zone for forming a high-temperature combustion gas stream; a second reaction zone having a choke portion for mixing a raw material hydrocarbon with the obtained high-temperature combustion gas stream to produce carbon black; In a method for producing carbon black using a production furnace having a third reaction zone downstream of two reaction zones and stopping the reaction, the concentration of oxygen in the combustion gas at the site where the raw material hydrocarbon is introduced is set to 3 vol% or less. A method for producing carbon black, characterized in that: 2. The temperature of a site for introducing a raw material hydrocarbon is set at 18
2. The method for producing carbon black according to claim 1, wherein the temperature is from 00 to 2400C. 3. The method for producing carbon black according to claim 1, wherein a production furnace having a choke portion length of 800 mm or more and a choke portion diameter of 170 mm or less is used. 4. A flow rate of a combustion gas in a choke portion is 250 m.
/ S or more. The method for producing carbon black according to claim 1 or 2, wherein 5. The method for producing carbon black according to claim 1, wherein the site for introducing the raw material hydrocarbon is located within the chalk portion and within 1 ms from the chalk inlet. 6. An average particle diameter of 25 nm or less, D _1/2 / D _mod
Carbon black having a ratio of 0.6 or less and a ratio of D ₇₅ / D _mod of 1.3 or less. 7. The method according to claim 6, wherein the average particle size is 20 nm or less.
The described carbon black. 8. The carbon black according to claim 6, wherein the dispersion index is 150 or less. 9. A _compound having a D _mod of 50 or less and an average particle size of 25 nm.
Hereinafter, carbon black having a ratio of D _1/2 / D _mod of 0.6 or less.