JP2820877B2 - Manufacturing method of furnace carbon black - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing furnace carbon black used for various applications such as a filling material, a reinforcing material, and a coloring material. The present invention relates to an improvement in a furnace method for easily and stably producing carbon black having a small specific surface area and suppressing the development of a structure.

[0002]

2. Description of the Related Art In general, in the production of carbon black by the furnace method, a high-temperature primary combustion gas generated by mixing and reacting a fuel and an oxidizing agent such as preheated air is used.
After introducing a liquid hydrocarbon raw material to cause a decomposition reaction, the mixture is rapidly cooled to produce carbon black.

Usually, the specific surface area of carbon black produced by the furnace method depends on the reaction temperature during the decomposition reaction, and the reaction temperature is controlled by the temperature of the primary combustion gas and the amount of the raw material introduced. In this case, the specific surface area decreases as the reaction temperature decreases, and the reaction temperature decreases as the primary combustion gas temperature decreases, and decreases as the amount of introduced raw materials increases. However, since the primary combustion gas has a role of supplying energy required for the decomposition of the raw material, the temperature of the primary combustion gas cannot be reduced without limitation. Therefore, the only way to produce carbon black with a small specific surface area by the furnace method is to increase the amount of raw material introduced, but simply increasing the amount of raw material introduced increases the amount of unreacted raw material. In addition, the transmittance of the produced carbon black in toluene coloring becomes low, causing the carbon black to adhere to and clog the inner wall of the device, making it impossible to operate the device.

[0004] When the amount of introduced raw material is increased, the amount of carbon black produced per unit volume of the reactor is increased. As a result, the generation of coke is promoted, and the amount of grit, which is a contaminant, is increased. The quality of the product deteriorates. To solve this problem, there is a method of increasing the reaction volume.However, the gas velocity in the reaction furnace is reduced, which causes a new problem that the generated carbon black tends to be deposited. Giant enlargement is not economically favorable.

What is determined by the reaction temperature is actually the primary particle diameter of carbon black, and the higher the reaction temperature, the smaller the primary particle diameter. On the other hand, the carbon black with a developed structure has a reduced specific surface area only at the fused portion of the primary particles, so that the carbon black with an undeveloped structure is smaller than the carbon black with a sufficiently developed structure when the primary particle diameters are equal. The surface area increases.

[0006] The structure of carbon black can be suppressed by introducing alkali metal ions into the reaction furnace. However, this method does not change the primary particle diameter. There is a feature that it is. Therefore, it can be seen that the production of carbon black having an undeveloped structure and a small specific surface area is more difficult by the furnace method.

To solve these conflicting demands, US Pat. No. 5,190,739 discloses a process for producing carbon black having a lower structure and a smaller specific surface area at the same overall burn rate, ie, the same raw material. Manufacturing methods that can simultaneously reduce the structure and specific surface area by the amount of introduction have provided important suggestions. However, this method itself has to introduce a highly flammable or explosive substance, a secondary hydrocarbon (or pure hydrogen) having a high hydrogen content, into the reaction zone, and actually produces carbon black having a small specific surface area. In the case of using it, there is a problem that it is necessary to ensure safety by managing extremely strict operating conditions and maintenance work.

In the improvement of the carbon black production method based on the furnace method, techniques for introducing water or water vapor in the vicinity of the reaction zone are disclosed in JP-B-54-7634, JP-A-56-24455, and JP-A-3-128974. Is disclosed. However, all of these inventions use an activation reaction with water vapor and are mainly used for coloring for 500 m.
^This is a method for producing carbon black having a large specific surface area of ² / g or more, and these methods cannot be directly used for the production of carbon black for rubber having a small specific surface area because the purpose is completely different. In addition, these inventions refer to the detailed description of the invention in the specification that a decrease in the temperature of the reaction zone caused when water or steam is introduced may be a factor inhibiting the production of carbon black.
No further detailed studies have been made, and it is impossible to actually produce carbon black having a small specific surface area using these inventions.

[0009]

SUMMARY OF THE INVENTION The present invention provides an improved carbon black having a small specific surface area, which has been difficult or impossible to produce by the ordinary furnace method, for easier and more stable production. The purpose is to develop a method for producing furnace carbon black.

[0010]

According to the present invention, a liquid hydrocarbon raw material is introduced into a high temperature primary combustion gas to cause a decomposition reaction.
In the furnace carbon black production method of quenching and producing carbon black, the distance (L) from the raw material introduction position to the water vapor introduction position is L / D ≦ L / D of the throat portion at the raw material introduction position. (1) and a method for producing furnace carbon black characterized in that steam is introduced from a position where the steam introduction position is different from the raw material introduction position, thereby suppressing the specific surface area and structure development of carbon black. The goal was achieved.

Hereinafter, the present invention will be described more specifically with reference to the drawings. FIG. 1 shows an example of a reaction furnace. First, production of carbon black by a general furnace method will be described with reference to this.

In the first region (S1), in the combustion chamber 1,
The fuel 2 and the oxidizing agent 3 such as preheated air are mixed and reacted to generate a high temperature primary combustion gas. In the subsequent second region (S2), the liquid hydrocarbon raw material 4 is introduced into the flow of the primary combustion gas to promote the thermal decomposition of the raw material and the formation of the carbon black precursor, and subsequently the growth of the carbon black primary particles. Finally, in the third region (S3), the reaction gas is quenched by introducing water or another cooling medium 5 to generate carbon black and terminate the reaction to produce carbon black.

In the above carbon black manufacturing method, the present inventors reduce the specific surface area of carbon black and suppress the development of structures by introducing steam 6 from a position near the raw material introduction position and different from the raw material introduction position. I discovered what I could do. As a result of further study, it has been found that the position of the carbon black is extremely important in controlling the specific surface area and structure of the carbon black by introducing the water vapor.

That is, in order to reduce the specific surface area of carbon black and suppress the structure, it is necessary to inhibit the formation of the carbon black precursor, which is the main reaction in the second region, by dense steam. The introduction position is in the vicinity of the upstream or downstream of the raw material introduction position but different positions, and the distance (L) from the raw material introduction position must be smaller than the throat diameter (D) at the raw material introduction position.

When the steam introduction position is the same position as the raw material introduction position, the spray particle diameter of the raw material liquid hydrocarbon becomes small due to the increase of the shearing force due to the introduction of steam, so that the contact with the high temperature primary combustion gas becomes good. As a result, the formation of the carbon black precursor is promoted, and the specific surface area of the generated carbon black increases. When L / D ≧ 1.0 and the steam introduction position is on the upstream side of the raw material introduction position, that is, when steam is introduced in the first region, the steam is already at a high temperature with the primary combustion gas at the raw material introduction position. It is sufficiently mixed, and the effect of introducing steam is to slightly lower the reaction temperature and slightly increase the partial pressure of H ₂ O in the primary combustion gas. The specific surface area and structure of the produced carbon black are hardly changed. Conversely, when L / D ≧ 1.0 and the steam introduction position is downstream of the raw material introduction position, the primary particles of carbon black have already grown considerably, and the introduction of steam into this region causes the carbon black surface Since the activated carbon forms micropores, the specific surface area of the generated carbon black increases.

Generally, in a furnace used for producing carbon black by the furnace method, a throat diameter at a raw material introduction position is optimized by a factor peculiar to each furnace. Therefore, the reaction states in the region determined by L / D <1.0 are equivalent for furnaces having shapes other than those shown in FIG. After all, when the steam is introduced from the region of L / D <1.0 irrespective of the reactor shape, the same effects as those described in the present invention can be obtained.

When the amount of introduced steam is less than 1% by weight relative to the amount of introduced raw material, the reduction of the specific surface area and structure of carbon black due to the introduction of steam is extremely small, and almost no effect is observed. Also, when the introduction amount of water vapor increases, the specific surface area of carbon black and the degree of decrease in the structure increase almost in proportion to the introduction amount of water vapor,
If the amount of introduced steam is too large, formation of the carbon black precursor is significantly inhibited, and the production of carbon black itself stops. It is difficult to introduce water vapor in an amount exceeding 15% by weight of the raw material introduced while continuing to produce carbon black.

[0018]

EXAMPLES As values for the carbon black specific surface area and the structure of each of the examples and comparative examples, values obtained by the following measuring methods were used.

Nitrogen adsorption specific surface area: Nitrogen adsorption specific surface area by BET method. The measurement method is based on ASTM D-3037.

Iodine adsorption amount: based on JIS K-6221.

DBP oil absorption; DBP is an abbreviation for dibutyl phthalate. Conforms to JIS K-6221.

Compressed DBP oil absorption: 24,000 [ps]
After compressive fracture of the structure is repeated four times by the load of i], the DBP oil absorption is measured. Measurement method is ASTM
Complies with D-3493.

In the examples and comparative examples, alkali metal ions for controlling the structure are added to the raw materials in the form of aqueous potassium ions. Table 1 shows the main characteristics of the fuel and raw materials used. The experiment was performed using the reactor shown in FIG.

The first zone length (S1) of the reactor is 3000
mm, the length of the second region (S2) is 15000 mm, and the throat diameter (D) at the raw material introduction position is 200 mm. The results obtained by the examples are shown in Table 2, and those of the comparative examples are shown in Table 3.

The specific surface area of carbon black depends on the structure. Further, the specific surface area of the carbon black produced by the furnace method has a certain lower limit due to the operation limit of the reactor. Therefore, in the furnace method, when a target of a certain structure is determined, a minimum value of the specific surface area corresponding to the target should exist, and this minimum specific surface area is referred to as a critical specific surface area. The critical specific surface area is
Values differ for reactors of different shapes. When the limiting specific surface area of the reaction furnace used in this example and the comparative example is expressed in consideration of the nitrogen adsorption specific surface area, the compressed DBP oil absorption amount, and the operating conditions, the equation (1) is obtained. [Limit specific surface area] = 78.5-0.748 x [Compressed DBP oil absorption] (1)

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

Since the critical specific surface area of the comparative example is the minimum specific surface area, the difference between the nitrogen adsorption specific surface area and the critical specific surface area takes a positive value, and the smaller the absolute value is, the closer the operating conditions of the reactor are to the limit. become. Therefore, this difference is defined as a critical specific surface area index. [Limit specific surface area index] = [Nitrogen adsorption specific surface area] − [Limit specific surface area] (2) When the critical specific surface area and the critical specific surface area index are calculated using the equations (1) and (2) as they are for the examples, The critical specific surface area index takes a negative value. That is, it was found that carbon black having a small specific surface area was obtained exceeding the critical specific surface area of the reactor exemplified by the introduction of steam, and that the present invention is extremely effective for producing carbon black having a small specific surface area. it is obvious.

[0030]

In the examples, since the absolute value of the critical specific surface area index directly indicates the effect of suppressing the carbon black specific surface area by the introduction of water vapor, for example, referring to the examples, the amount of water vapor introduced is about 3%. , Maximum, about 14m ² / g
It can be seen that there is the above specific surface area suppressing effect. According to the calculation from the heat balance, the reaction temperature is about 7 ° C when 1% of steam is introduced.
descend. In the case of the illustrated reactor, a decrease in the reaction temperature of 7 ° C. causes only a decrease in the specific surface area of about 1 to ² m ² / g, so it is clear that the main factor of the suppression of the specific surface area is not a decrease in the reaction temperature due to the introduction of steam. is there.

Further, when the method of the present invention is used, carbon black having a small specific surface area comparable to the specific surface area of thermal grade carbon black which cannot be produced by the conventional furnace method as shown in Example 4 can be produced. can do. Moreover, these carbon blacks have a much higher structure than thermal-grade carbon blacks, and have specificity not found in conventional carbon blacks.

[Brief description of the drawings]

FIG. 1 is an example of a carbon black reactor for carrying out the present invention.

[Explanation of symbols]

 Reference Signs List 1 combustion chamber 2 fuel 3 oxidant such as air 4 liquid hydrocarbon raw material 5 cooling medium such as water 6 steam L distance between feed introduction position and steam introduction position D Throat diameter

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ryoichi Adachi 3-23-5 Nishishinbashi, Minato-ku, Tokyo Inside Showa Cabot Co., Ltd. (56) References JP-A-61-148270 (JP, A) JP-A Hei 3-128974 (JP, A) JP-A-2-49072 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09C 1/00-1/60

Claims (2)

(57) [Claims] In a method for producing a furnace carbon black in which a liquid hydrocarbon material is introduced into a high-temperature primary combustion gas to cause a decomposition reaction, quenched, and produce carbon black, a distance from a material introduction position to a steam introduction position. (L) is the diameter of the throat portion at the raw material introduction position (D)
Whereas, L / D ≦ 1, and steam is introduced from a position where the steam introduction position is different from the raw material introduction position to suppress the specific surface area and structure development of the carbon black. Production method. 2. The method for producing furnace carbon black according to claim 1, wherein the amount of the introduced steam is in the range of 1% by weight to 15% by weight of the amount of the raw material introduced.