JPH10140035A - 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 mixing rate of turbulent flow at the choke unit through which the stock carbon black is introduced is set at >=120m/s.

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. Further, it is known that such carbon black exhibits a high degree of wear resistance when used as a tire reinforcing agent.

[0004] The distribution of the primary particle size also has a significant effect on the rubber properties, particularly on tire tread rubber compositions which require high abrasion resistance, and it is said that the narrower the primary particle size distribution is, the better. Generally, the smaller the average particle diameter, the narrower the distribution. However, a method of narrowing the primary particle diameter distribution has also been disclosed (Japanese Patent Laid-Open No. 33167/1991). 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.

[0005] Agglomerates have a significant effect on the properties of carbon black, and many of the properties of carbon black, which have heretofore been attributed to the primary particle size, can sometimes be better explained by the aggregate size. It has become clear. For example, it is considered that the aggregate diameter and its distribution play 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 for 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.

[0007]

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, and a small width of aggregate distribution.

The present inventors analyzed the dispersion behavior of carbon black in a matrix and the factors affecting blackness,
Compared with the prior art, as a result of various studies to obtain carbon black having higher blackness and good dispersibility, that fine aggregates adversely affect dispersion, large aggregates adversely affect blackness, Therefore, it has been found that carbon black having uniform aggregates without fine aggregates or large aggregates has high blackness and good dispersibility. In other words, carbon black having a small particle diameter, a small aggregate diameter, and a sharp distribution of aggregate diameters has high blackness and good dispersibility, that is, solves the problem of blackness and dispersibility which have been considered to be the above two trade-offs. It was discovered that it was something to do.

Therefore, the present inventors have conducted further intensive studies and searched for conditions for producing carbon black having the above-mentioned excellent characteristics. As a result, the following was found. First, in order to achieve a smaller primary particle size,
Immediately after the introduction of the raw material hydrocarbon, it was found that it was effective to minimize the droplet diameter of the raw material hydrocarbon immediately after the raw material hydrocarbon was introduced into the combustion gas in the production furnace.

Next, control of the size of the primary particle diameter and the diameter of the aggregate was examined. As a result, in order to produce carbon black having a small particle size and a small aggregate size, it is necessary to shorten the time from carbon black generation to carbonization, that is, to generate carbon black within a short time as possible. It turned out to be. For this purpose, it is necessary to shorten the time until the liquid raw material hydrocarbon is sprayed into the combustion gas and the liquid raw material evaporates, and it is necessary to shorten the time for forming the carbon black precursor and the carbon black. After the raw hydrocarbon is introduced into the hot gas,
It is necessary to efficiently absorb the heat energy of the surrounding hot gas.

[0011]

Means for Solving the Problems The present inventors further reduced the droplet diameter of the raw material hydrocarbon and shortened the reaction time for producing carbon black by efficiently using the ambient heat gas energy. At the same time, as a result of exploring various conditions for satisfying, it was found that the above object can be achieved by setting the site for introducing the raw material hydrocarbon into a specific state.

That is, the present invention provides a first reaction zone for forming a high-temperature combustion gas stream, and a step of mixing raw 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 second reaction zone having a chalk portion and a third reaction zone downstream of the second reaction zone and stopping the reaction, a turbulent flow at a portion where a raw hydrocarbon is introduced Mixing speed of 120
/ S or more.

By changing various conditions such as, for example, the amount of raw material hydrocarbon inserted within the range defined in the production method of the present invention, carbon black having various desired physical properties can be produced. Therefore, various kinds of carbon blacks that can be used for various purposes can be arbitrarily produced in high yield.

[0014]

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 for mixing the obtained high-temperature combustion gas stream with a raw material hydrocarbon to form carbon black, and a third reaction downstream of the second reaction zone for stopping the reaction. Band 3 is classified. 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 starting hydrocarbons are spray-injected from the starting hydrocarbon introducing nozzle 6 provided in parallel or in the horizontal direction with the high-temperature gas stream obtained in the first reaction zone, and the starting hydrocarbons are 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 figure, 4 is a refractory furnace and 8 is a control valve.

The third reaction zone is provided with a high-temperature reaction gas of 1000-1000.
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. Here, the present invention is characterized in that the intensity of turbulent mixing of the combustion gas flow at the site where the raw material hydrocarbon is introduced is within a specific range. That is, the turbulent mixing speed at the portion where the raw hydrocarbon is introduced is 12
0 / s or more. As a result, it has been found that carbon black having a small particle diameter and a small aggregate diameter and a sharp aggregate distribution can be efficiently produced.

The turbulent mixing speed having such a large value not only promotes the atomization of the raw material hydrocarbon droplets, but also makes the atmosphere in which the carbon black formation reaction takes place uniform and makes the combustion gas Since the heat energy possessed can be efficiently used for the carbon black formation reaction,
It is considered that the reaction speed is increased and the reaction field becomes uniform, and as a result, it is possible to efficiently produce carbon black having a small particle diameter and a small aggregate diameter and a sharp aggregate distribution.

Here, the physical quantity called the turbulent mixing speed is introduced as an index indicating the strength of the turbulent mixing. This is a physical quantity obtained by dividing the turbulent vortex dissipation rate ε (m ² / s ³ ) by the turbulence energy intensity k (m ² / s ² ), and has a dimension of (1 / time). This is one index indicating the strength of mixing. These ε and k are physical quantities generally used to represent the magnitude of turbulence in hydrodynamics. ε and k
Can be obtained using a known means such as numerical calculation.
In the present invention, a general k-ε model is used as a turbulence model for performing numerical calculations.

As a result of various studies, the inventors have found that there is a correlation between the value of ε / k of the gas flow at the position where the starting hydrocarbon is introduced and the quality of the carbon black produced. That is, when the turbulent mixing speed (ε / k) at the position where the raw material hydrocarbon is introduced is in a specific range, the primary particle size to be formed is small, the aggregate size is small, and the aggregate has sharp desirable physical properties. It turned out to be.

To increase the value of ε / k, it is effective to increase the gas flow velocity in the choke, but ε / k can also be increased by reducing the diameter of the choke.
Also, the angle of the reduced portion of the choke inlet is important, and the steeper the angle, the larger ε / k. Thus, the inventors theoretically elucidated a method for efficiently producing carbon black having a small particle diameter, a small aggregate diameter and a sharp distribution of the aggregate diameter. Simulations and experiments are performed under various conditions, and the value of ε / k at the position where the raw material hydrocarbon is introduced is required to be at least 120 / s or more.
It has been found that 00 to 5000 / s is particularly suitable.

The diameter of the choke is preferably 170 mm or less, and more preferably 30 to 150 mm. The higher the gas flow rate in the feed hydrocarbon introduction part, the better, but it is preferably 250 m / s or more, more preferably 300 m / s or more, and even more preferably 50 m / s or more.
It is about 0 m / s. The temperature at the site where the raw material hydrocarbon is introduced is preferably 1600 to 1700 ° C, more preferably 1700 to 2400 ° C, and further preferably 18 ° C.
00 to 2400 ° C. In this range, a particularly high temperature atmosphere is provided for the raw material hydrocarbons to be uniformly vaporized and thermally decomposed, and the carbon black becomes particularly sharp in distribution of aggregates and particle size.

In order to uniformly disperse the raw material hydrocarbons in the furnace, it is preferable that the raw material hydrocarbons are introduced into the furnace from two or more nozzles. By doing so, carbon black having a particularly small aggregate diameter can be produced.
The feed position of the raw material hydrocarbon is within the choke section and from the chalk inlet by 1 to the cross-sectional average flow velocity of the combustion gas.
The range is preferably within ms. 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.

Oxygen concentration at the feed hydrocarbon feed position
Is preferably 3 vol% or less. More preferred
Is 0.05 to 1 vol%. For the study of the present inventors
More surprisingly, the presence of oxygen in the combustion gas
Partial combustion of the feedstock hydrocarbons, thereby
It was found that uniformity occurred. Conventional technology
When slabs are formed by partial combustion of feedstock
It was thought that the residual oxygen concentration in the combustion gas was
About 10 vol%, and partially burn the raw oil
However, surprisingly, raw materials hydrocarbons were
The lower the oxygen concentration at the site to be introduced, the more the combustion reaction
CO in _TwoIncrease in the combustion reaction
The calorific value increases and the temperature of the combustion gas increases.
And that the yield also improves significantly.
Because of low combustion, the area where carbon black is generated
The atmosphere is kept uniform and the aggregate size distribution is particularly sharp
It has been found that carbon black can be obtained.

The measurement of the oxygen concentration at the starting hydrocarbon introduction site is performed by collecting the gas at the starting hydrocarbon introduction site,
For example, nitrogen, oxygen,
It can be determined by measuring carbon dioxide, carbon monoxide, hydrogen, methane, and acetylene. Water generated by combustion is not included in the calculation. 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, centrifugal sedimentation in an aqueous dispersion of cDBP or carbon black and electron microscopic analysis have been known as evaluation indexes for aggregates.
Recently, centrifugal sedimentation has been used to evaluate the size and distribution of aggregates. In Examples of the present invention, as an index 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. _Two
Was evaluated using the ratio of

[0027]

EXAMPLES The present invention will be described more specifically below with reference to examples. (Examples 1 to 7) As shown in FIG. 1, 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 is connected to the first reaction zone, and a plurality of raw material nozzles are penetrated from the periphery. 50mm inside diameter, 300mm 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, and a carbon black production furnace having a structure in which a control valve having an inner valve diameter of 80 mm is sequentially connected as a throttle mechanism are installed. did. The raw material nozzle position is 100
mm.

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 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.

A 20% ethanol solution was used as a spin solution, and the Stokes equivalent diameter was measured by a centrifugal sedimentation type flow rate distribution measuring device (DCF3, manufactured by JL Automation). 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. (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. Compounding 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.

Conditions for preparing diluted compound LDPE resin 58.3 g Calcium stearate 0.2 g Carbon black 40% blended resin 1.5 g A sheet having a slit width of 0.3 mm was cut into chips, which were cut into chips and placed on a hot plate at 240 ° C. for 65 mm. ± 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.

[0033]

[Table 1]

[0034]

[Table 2]

(Comparative Example) When the turbulent mixing speed is 117 / s (the choke diameter is 50 mm and the flow rate in the choke is 80
m / s, and the flow velocity in the choke is 250 m / s
s and the chalk diameter is 180 mm) were taken as Comparative Example 1 and Comparative Example 2, respectively. Other conditions are as described in Example 1.
A carbon black was produced in the same manner as described above. Table 2 shows the physical properties of the obtained carbon black.

As shown in Table 2, Comparative Example 1 was obtained from Examples 1 to
Compared with No. 5, D _1/2 / D _mod is large, the blackness is low, the dispersion index is high, and the dispersibility is poor. Comparative Example 2 has a specific surface area N
₂ SA is small, particle size is large, and high blackness is low.

[0037]

As described above, the carbon black according to the present invention, when used as a black pigment in resin colorants, printing inks and paints, exhibits blackness and dispersibility, which have conventionally been in a trade-off relationship and have been considered difficult. To be satisfied. 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 ).

[Explanation of symbols]

 4 Refractory furnace 8 Control valve

 ──────────────────────────────────────────────────続 き Continued 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 (2)

[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 having a reaction stopped, a turbulent mixing speed at a site where a raw material hydrocarbon is introduced is 120 / s or more. Characteristic method for producing carbon black. 2. The method for producing carbon black according to claim 1, wherein the oxygen concentration in the combustion gas at the site where the raw material hydrocarbon is introduced is 3 vol% or less.