JPH11106676A - Carbon black producing apparatus and production of carbon black using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing carbon black satisfying both of high black degree and good dispersibility and a method for efficiently producing carbon black having small primary particles, small aggregate, small width of aggregate distribution. SOLUTION: This apparatus for producing carbon black has a first reaction zone for forming high-temperature combustion gas stream, a second reaction zone having a choke part for producing carbon black by mixing the resultant high-temperature combustion gas stream with a raw material hydrocarbon and a third reaction zone for stopping the reaction in the downstream of the second reaction zone. In this case, the length of the choke part is >=800 mm and the diameter of the choke part is <=170 mm.

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 filling materials, reinforcing materials, conductive materials and coloring pigments, and to an effective production apparatus and method for controlling the physical properties thereof. Things.

[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 size 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 flow in a choke section provided in a second reaction zone (also referred to as a carbon black producing region). It is well known that the use of gas motion and thermal energy to atomize a liquid feedstock is effective. Further, the distribution of the primary particle diameter also has a significant effect on the rubber properties, particularly on the tire tread rubber composition which is required to have high abrasion resistance, and it is said that the narrower the primary particle diameter distribution is, the more preferable. In general, the smaller the average particle size, the narrower the distribution, but it also discloses that the primary particle size distribution is narrowed.

For example, Japanese Patent Application Laid-Open No. 3-33167 discloses that the length of a choke is large enough to allow the carbon black formation reaction to be substantially completed, so that the chalk is formed at an enlarged portion at the outlet of the choke portion. A method is disclosed in which carbon black having a relatively narrow particle size distribution is obtained by a method that does not exert the influence of a swirling current, so-called "back mixing" 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 for reducing the diameter of the aggregates, an alkali metal salt or a solution thereof is added to a raw material oil, burned or introduced into 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. In addition, there is a problem of efficiently producing such carbon black.

[0009]

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 apparatus and 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.

[0010]

Means for Solving the Problems The present inventors analyze the dispersion behavior of carbon black in a matrix and the factors affecting blackness to obtain carbon black having higher blackness and better dispersibility than before. As a result of various investigations, it was found that fine aggregates had an adverse effect on dispersion, large aggregates had an adverse effect on blackness, and therefore carbon black having uniform aggregates without fine aggregates and large aggregates was They were found to have high blackness and good dispersibility. That is, it is considered that the carbon black having a small particle diameter, a small aggregate diameter, a sharp distribution of the aggregate diameter, and a large aggregate diameter does not exist, has a high degree of blackness and good dispersibility, that is, has the above-described trade-off relationship. It has been found to solve the problems of blackness and dispersibility that have come. Further, as a result of further intensive studies on efficient conditions for obtaining carbon black having such excellent characteristics, it was found that the above object can be achieved by using a carbon black producing apparatus having a specific chalk portion. This has led to the present invention. That is,
The present invention provides a first reaction zone in which a high-temperature combustion gas stream is formed, a second reaction zone having a choke portion for mixing a raw material hydrocarbon with the obtained high-temperature combustion gas stream to generate carbon black, A carbon black producing apparatus having a third reaction zone downstream of two reaction zones and stopping the reaction, wherein the length of the choke portion is 800 mm or more and the diameter of the choke portion is 170 mm or less. Apparatus, a method for producing carbon black using such a production apparatus, and the like.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The present invention provides a carbon black producing apparatus having a first reaction zone, a second reaction zone, and a third reaction zone, wherein carbon black is obtained by introducing a raw material hydrocarbon.
It relates to the so-called furnace method.

The configuration of the present invention will be described with reference to the drawings. FIG. 1 is a schematic longitudinal sectional view of an essential part showing an example of the carbon black producing apparatus of the present invention. The furnace has a first reaction zone 1 for forming a high-temperature combustion gas stream in a longitudinal direction, and a second reaction zone having a choke section for mixing a raw material hydrocarbon with the obtained high-temperature combustion gas stream to produce carbon black. 2 (having a choke portion 4) and a third reaction zone 3 which is downstream downstream of the second reaction zone and stops 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. Air, oxygen or mixtures thereof are used as the oxygen-containing gas, and hydrogen, carbon monoxide, natural gas, petroleum gas and petroleum liquid fuels such as heavy oil, coal-based liquid fuels such as creosote oil are used as fuel hydrocarbons. Is used.

In the second reaction zone, the raw hydrocarbon is sprayed and introduced into the choke section from the 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.
The raw hydrocarbon is pyrolyzed and converted into carbon black. The raw material hydrocarbons are generally aromatic hydrocarbons such as benzene, toluene, xylene, naphthalene and anthracene; coal-based hydrocarbons such as creosote oil and carboxylic acid oil; and heavy petroleum oils such as ethylene heavy-end oil and FCC oil. And acetylenically unsaturated hydrocarbons, ethylene hydrocarbons, and aliphatic saturated hydrocarbons such as pentane and hexane.

In the third reaction zone, the high-temperature reaction gas is
Water or the like is sprayed from the reaction stop fluid introduction nozzle 7 in order to cool it to 800 ° C. or less. The cooled carbon black is subjected to a known general process such as separation and recovery from gas with a collecting bag filter or the like. The present invention is characterized in that a specific choke portion is used in the above-mentioned second reaction zone. That is, the length is 800 m
m and a diameter of 170 mm or less.

The length of the choke portion is 800 mm or more, preferably 800 to 3000 mm. The present inventors have found that the diameter of the aggregate of the obtained carbon black can be particularly reduced in this range. It should be noted that no special effect is obtained even if it exceeds 3000 mm.
It is desirable to have the following length.

Further, not only the chalk length but also the choke diameter influences the diameter of the aggregate. When the chalk portion length is set to a specific value or more and the choke diameter is set to a specific value or less,
It was found that the distribution of the aggregates was extremely sharp, and that the carbon black had very good physical properties. That is, in the present invention, the diameter of the choke is set to 170 mm or less. Preferably 30 to 170
mm, particularly preferably 50 to 150 mm.

A method for obtaining a carbon black having a relatively narrow particle size distribution while maintaining a long choke length is disclosed in Japanese Patent Laid-Open No. 3-3 / 1991.
No. 3167. However, there is no description about the effect on the aggregate size distribution, which is the most important factor affecting the properties of carbon black, and the preferred size of the chalk is 7 to 10 inches in diameter. There is only. The present invention
By setting the chalk diameter and the chalk diameter to a specific range simultaneously with the length of the chalk portion, it is possible to obtain carbon black having a small aggregate diameter and a small distribution with a large aggregate diameter, Is unexpected.

As described above, according to the present invention, it is possible to obtain carbon black having a uniform aggregate diameter and no large aggregate diameter because carbon black primary particles and aggregates are formed after the raw material hydrocarbon is supplied. It is possible to keep the reaction zone conditions uniform, and to provide high disturbance due to a drastic change in the cross-sectional shape of the flow channel until the reaction in which the primary particles and agglomerates of carbon black are formed after the supply of the raw material hydrocarbon is completed. It is considered that it is not possible.

The aggregate of carbon black is obtained by thermally decomposing the raw material hydrocarbon, condensing it, agglomerating it into droplets, forming a nucleus precursor, forming primary particles, and then fusing the particles through mutual collision. It is considered to be carbonized and formed. Therefore, it is considered desirable to lengthen the chalk portion and the aggregate generation region does not have a high disturbance field due to a change in the flow path of the throttle portion or the like. The inventors of the present invention have found that control over a longer period of time is required as compared with control. Therefore, in the present invention, it is considered that the above-mentioned problem can be solved by setting the length of the choke to 800 mm or more. In particular, the results of various experiments have revealed that maintaining the length of the chalk at a specific value or more has a remarkable effect in preventing the formation of large aggregate diameters.

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. Further, 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. Keeping the gas in the chalk at a high speed makes it possible to use the kinetic energy and heat energy of the combustion gas for refining the raw material hydrocarbons, resulting in a carbon black with a small particle size,
It is considered that the turbulent mixing in the chalk uniformizes the atmosphere in which the carbon black generation reaction takes place, thereby obtaining carbon black having a small particle size distribution. In addition, since the thermal energy of the combustion gas can be efficiently used for the carbon black generation reaction, the reaction speed increases,
Further, it is considered that the reaction field becomes uniform, and as a result, carbon black having a small aggregate diameter can be produced.

The feed position of the raw material hydrocarbon is also an important factor. According to the study of the present inventors, in order to produce carbon black having a small particle diameter and a uniform agglomerate diameter, the hydrocarbon feed position must be choke. It has been found that it is suitable to be located at a position within 1 ms, more preferably within 0.6 ms, based on the cross-sectional average flow velocity of the combustion gas from the chalk inlet.

In the present invention, the length and the diameter of the choke portion are defined. Here, the inlet of the choke portion, which is the starting portion of the choke portion, includes the narrowest portion of the flow channel and the axis where the flow channel is reduced. A portion where the angle to the direction changes from a value exceeding 5 ° to 5 ° or less. On the other hand, the outlet of the choke portion, which is the terminal end 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 °.

In the combustion zone, that is, the first reaction zone, it is desirable to suppress the oxygen concentration in the combustion gas as much as possible. The present inventors have found that the presence of oxygen in the combustion gas causes partial combustion of the raw material hydrocarbons in the reaction zone, that is, the second reaction zone, which may cause non-uniformity in the reaction zone. . The oxygen concentration in the combustion gas is preferably 3 vol% or less, more preferably 0.05 to 1 vol%.

The temperature of the combustion zone is preferably a sufficiently high temperature atmosphere for the raw material hydrocarbons to be uniformly vaporized and thermally decomposed, preferably from 1600 to 1800 ° C, more preferably from 1700 to 2400 ° C. By using the above-described apparatus for producing carbon black of the present invention or by producing carbon black by the method for producing carbon black of the present invention, carbon black having excellent properties can be efficiently obtained. 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. ing. In the embodiment of the present invention, the half-width D1 _{/ 2} of the maximum frequency Stokes equivalent diameter Dmod and the maximum frequency Stokes equivalent diameter in the aggregate Stokes equivalent diameter distribution by centrifugal sedimentation as an index of the sharpness of the aggregate diameter. the ratio, also was evaluated using D ₇₅ as an indication that there is no large agglomerates diameter.

According to the apparatus for producing carbon black of the present invention and the method for producing carbon black of the present invention, the maximum frequency Stokes equivalent diameter Dmod and the maximum frequency Stokes equivalent in the aggregate Stokes equivalent diameter distribution by the centrifugal sedimentation method have an average particle diameter of 25 nm or less. Ratio of half width of diameter, ie D _1/2
/ D _mod ratio is 0.6 or less, volume 75% diameter and D _mod ratio D
It is possible to efficiently obtain carbon black having a ₇₅ / D _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. Furthermore, carbon black having an average particle diameter of 20 nm or less, which is more preferable for increasing the PVC blackness, can be easily obtained.

[0027]

The present invention will be described more specifically with reference to the following examples. (Examples 1 to 5) 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. 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,
Further, a carbon black manufacturing apparatus having a structure in which control valves having an inner valve diameter of 80 mm were sequentially connected as a throttle mechanism was installed.

Using the above production apparatus, carbon black was produced according to the conditions shown in Table 1. Fuel and
Creosote oil was used as the starting hydrocarbon. Table-1
The “combustion gas temperature”, “combustion gas oxygen concentration” and “furnace pressure” are those at the site where the raw 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 AS
Determined according to TM D3037-88. (CDBP) Crushed DBP absorption number (cDBP) is ASTM
Determined according to D-3493-88.

(D _mod , D _1/2 ) The maximum frequency Stokes equivalent diameter (D _mod ) and Stokes equivalent diameter _half width (D _1/2 ) were 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 relative occurrence frequency of the Stokes equivalent diameter to a given sample was measured. (FIG. 2). 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. Line (G) is the distribution curve of the histogram.
Intersect at two points D and E. 2 points D of carbon black particles
And the absolute value of the difference of the two Stokes diameters of E is Stokes equivalent径半width D _1/2 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 is determined from each Stokes diameter and frequency from FIG. 2, and the Stokes diameter versus the volume of the sample obtained up to that diameter Make a graph that represents the sum. (Fig. 3)
Therefore, the 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) parallel to the X-axis until the curve intersects. A line is equilibrium drawn from the point (C) to the Y axis, and the value of the point (D) crossing the X axis is the volume 75% diameter (D75).

(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 a carbon black “# 40” or “# 45” manufactured by Mitsubishi Chemical Corporation. The blackness was defined as a reference value of 1 point and 10 points, respectively, and the blackness of the material was evaluated by visual perception.

(Dispersion index) The dispersion index was evaluated by the following method. The state of dispersion in the LDPE 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 was evaluated.

LDP with 250cc Banbury mixer
E resin mixed with 40% by weight of sample carbon black
Knead at 5 ° C for 4 minutes. Formulation 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% compounding resin 1.5 g

The sheet is formed into a sheet with a slit width of 0.3 mm, cut into chips, and formed into a film of 65 ± 3 μm on a hot plate at 240 ° C. 0.2 m in a visual field of 3.6 mm x 4.7 mm using an optical microscope with a magnification of 20 times.
The diameter distribution of undispersed aggregates with a diameter of at least m is measured 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. Observe this for more than 16 fields of view,
The average value is taken as the dispersion index.

(Particle Size) According to electron microscopy. Electromicroscopy 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 1
The measurement is performed 500 times, and an arithmetic average of those values is obtained.

[0038]

[Table 1]

[0039]

[Table 2]

(Comparative Examples 1 to 5) Comparative examples 1 to 5 were used under the conditions shown in Table 1 by using the apparatus for manufacturing carbon black used in the examples in which the length of the chalk portion was changed to 500 mm.
No. 3 was prepared, and its physical properties are shown in Table 2. Comparative Examples 4 and 5 are Mitsubishi Chemical Corporation, respectively.
Commercial carbon black "# 990" and "# 96
0 ". When the obtained carbon black of the present invention is compared with a comparative example, as is clear from Table 2, the carbon black obtained in the example has a smaller D _1/2 / D _mod than the carbon black of the comparative example. Aggregate size distribution is sharp. Further, D ₇₅ is small, and those having a large aggregate size are few. In addition, it exhibits high blackness, low dispersion index,
Good dispersibility.

[0041]

As described above, when the carbon black according to the present invention is used as a black pigment in resin colorants, printing inks and paints, the blackness and the dispersion which have been considered to be difficult because of the trade-off relationship between them are conventionally considered. Satisfies the nature. 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 an apparatus for producing carbon black of 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.

[Explanation of symbols]

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

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroaki Takehara 1-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu City, Fukuoka Prefecture Inside the Kurosaki Office of Mitsubishi Chemical Corporation (72) Inventor Mamoru Nakayama 1 Tohocho, Yokkaichi City, Mie Prefecture Mitsubishi Chemical Inside Yokkaichi Research Institute, Inc.

Claims (5)

[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; A carbon black producing apparatus having a third reaction zone downstream of two reaction zones and stopping the reaction, wherein the length of the choke portion is 800 mm or more and the diameter of the choke portion is 170 mm or less. apparatus. 2. A second reaction zone having a first reaction zone for forming a high-temperature combustion gas stream and a choke section 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 carbon black production apparatus having a reaction zone and a third reaction zone downstream of a second reaction zone and stopping the reaction, wherein the length of the chalk portion is 800 mm or more, A method for producing carbon black, wherein the diameter of the portion is 170 mm or less. 3. The flow rate of the combustion gas in the choke portion is 250 m.
3. The method for producing carbon black according to claim 2, wherein the carbon black is not less than / s. 4. The method for producing carbon black according to claim 2, wherein the spray position of the raw material hydrocarbon in the choke portion is within 1 ms from the chalk inlet. 5. The method for producing carbon black according to claim 2, wherein the oxygen concentration in the combustion gas at the position where the raw hydrocarbon is introduced in the choke portion is 3 vol% or less.