JPH1053723A - Novel carbon black - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a novel carbon black improved in abrasion resistance, hysteresis characteristics, reinforcing properties and processability by specifying its nitrogen adsorption specific surface area and its aggregate size distribution index. SOLUTION: The amount of a fuel fed into a reaction chamber 11 from feed ports 2 and 3, the amount of an oxygenous gas and/or a fuel oil fed into a combustion chamber 2 from feed inlets 5-10, the amount of an oxygenous gas or feedstock oil fed into the Venturi reaction zone 11 from feed ports 12-15 and the amount of an oxygenous gas or a feedstock oil fed into the Venturi rear reaction chamber 18 from feed ports 16 and 17 are being regulated, while the position where cooling water is injected and sprayed into a reaction continuation and quenching chamber 19 is adjusted to obtain a carbon black satisfying the relationships: 0.385+(0.0005×N2 SA)>=Z>=0.218-(0.0005×N2 SA) (wherein N2 SA is the nitrogen adsorption specific surface area, and Z is the aggregate size distribution index).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to carbon black for use in automobile tires, other automobile parts, industrial belts, hoses or other rubber products, and a rubber composition containing the carbon black.

[0002]

2. Description of the Related Art Carbon black can be added to and blended with natural rubber or various synthetic rubbers to impart reinforcement, wear resistance, etc. to those rubbers. However, since rubber products are used in various fields and products, the properties of carbon black differ from product to product.For example, in the case of automobile tires, the tires are required to have wear resistance and low heat build-up, In addition, other automotive parts are required to have durability, and various rubber products such as belts and hoses are generally required to have various characteristics such as workability, workability, and extrudability. For this reason, it is necessary to select and use the most appropriate carbon black in consideration of the above-mentioned characteristics.

It is well known that each of the above rubber properties is greatly affected by the physicochemical properties of carbon black compounded in the rubber. The basic characteristics of carbon black are the particle diameter or specific surface area, the structure and surface properties that are the connection between particles, and the properties of the rubber composition containing carbon black are influenced by the combination of the three. Is known empirically.

The method of evaluating the particle size of carbon black is a direct measurement method using an electron microscope, the method of evaluating the surface area is a method of directly measuring the projected surface area photographed by an electron microscope, and the nitrogen adsorption specific surface area (N the method according to ₂ SA), or other gas phase adsorption or iodine, diphenyl grayed crocodile Jin (DPG), the method according to the liquid phase adsorption of solution containing cetyltrimethylammonium bromide (CTAB) or the like is selectively used. Since the particle diameter and the specific surface area are generally in inverse proportion, the specific surface area tends to increase as the particle diameter decreases. When a carbon black having a small particle diameter, that is, a large specific surface area is added to, for example, a rubber composition for an automobile tire tread, hysteresis characteristics such as heat generation and the like are increased while tire reinforcement and wear resistance are improved. Tend.

[0005] The structure is defined as a chain-like connection observed when the carbon black is observed with an electron microscope, and it is empirically known that the larger the void amount of the carbon black, the more the chain-like structure is developed. As a practical measure of the structure, a method of exclusively measuring the absorption amount of oil such as oil has been used for a long time, and the absorption amount of dibutyl phthalate (DBP) is specified in JIS K6210. In recent years, 24,000P carbon black
After four repetitive compression treatments at Si (165MPa) pressure, DBP
The so-called 24M ₄ DBP (also called Crushed DBP) for measuring the amount of absorption is specified in ASTM D3493. When carbon black having a well-developed structure, that is, a large amount of dibutyl phthalate absorption, is added to rubber, the extrusion characteristics, tensile strength, and the like of the compounded rubber product can be improved.

[0006] Carbon black is not a substance having 100% carbon, but has various functional groups on its surface, and these are expressed as surface properties. There is also a method of evaluating the surface properties by chemically measuring those individual functional groups,
The method generally used industrially is pH, which is also specified in JIS K6201. However, these carbon black characteristics are macro-types that capture carbon black as one lump, and under the circumstances where special characteristics are required for various rubber products with recent technological progress,
It has become difficult to sufficiently grasp the characteristics of the compounded rubber composition only from these basic characteristics or combinations thereof.

Therefore, a method has been developed for optically measuring and analyzing the microaggregate structure of carbon black based on the Stokes principle. The mode diameter of the aggregate size of carbon black, that is, the average diameter of the aggregate size distribution and the aggregate size The characteristics of carbon black are specified by the combination of the distribution width at 50% of the most frequent value of the size distribution (hereinafter referred to as "half width"), and when such carbon black is compounded with a specific rubber type, the physical properties of the compounded rubber are determined. There have been many suggestions that can be improved. For example, JP-A-56-106936, JP-A-57-10
No. 8163, JP-A-2-34643, JP-A-3-281549, etc. specify the specific surface area or the particle size characteristics and the structure characteristics of carbon black by any method and set the aggregate size mode diameter and half width to a certain range. It is a proposal to limit to, and JP-A-62-104850, JP-A-62-277443,
JP-A-3-111455, JP-A-6-506870, JP-A-6-93136
No., JP-A-6-93137, etc., a proposal to limit the ratio of the half-width of the aggregate size distribution of carbon black and the aggregate size mode diameter to a certain range, and further JP-A-59-47263, No.62-30137, JP-A-1-20136
No. 7, JP-A-2-11664, and JP-A-3-227343, there are various proposals in which the aggregate size mode diameter of carbon black and the like are expressed in combination with other carbon black characteristics.

[0008]

However, if the relationship between the aggregate size mode diameter and the half-value width of the carbon black is simply determined uniformly, any one of the values of the aggregate size mode diameter and the half-value width changes. Since the other value also changes, for example, even if the distribution of the half-value width is narrow, it cannot be distinguished whether the aggregate size mode diameter is small or the distribution itself is narrow. Therefore, in order to clarify this distinction and specify the characteristics of carbon black, utilizing a fact that this aggregate size distribution approximately follows a lognormal distribution, a constant factor corresponding to the standard deviation is introduced, Expressing the relationship between the aggregate size mode diameter and the half width is an effective means.

[0009]

Means for Solving the Problems The factor Z here corresponds to the standard deviation in the aggregate distribution curve, and the relationship between the aggregate size mode diameter and the half width is examined by introducing such a factor. Carbon black having a relatively large specific surface area used for the rubber composition application of the tread portion of the tire, and a portion other than the tread of the tire, that is, the specific surface area used for the rubber composition used for the carcass portion and other automobile parts. In both cases, for relatively small carbon blacks, the factor Z is the specific surface area of the carbon black (N ₂ S
In the case of using a certain mathematical expression in relation to A), it has been found that a rubber composition containing carbon black can be provided with new properties that cannot be achieved with conventional carbon black. .

At present, carbon black used for rubber compounding is mainly produced by an oil furnace method, and is a soot obtained by incompletely burning an aromatic liquid oil. It is thought that these carbon atoms are bonded to form unit particles, and these unit carbon particles are fused to each other to form a structure. Has been confirmed by electron micrographs and the like of rubber containing carbon black. In the measurement of the aggregate size, the size of the aggregate was conventionally measured by taking an electron micrograph of carbon black sufficiently dispersed in a liquid, classifying and measuring its shape. there were. However, since the shape of each aggregate of carbon black is irregular and it is not easy to quantitatively evaluate it, it is not practical as a method for evaluating carbon black.

For this reason, the Stokes principle was applied, in which carbon black was uniformly dispersed in a certain solvent using ultrasonic waves, and when a centrifugal force was applied to this dispersion solution, the larger the aggregate size, the faster the sedimentation. An analysis method using the centrifugal sedimentation method has been developed and is now being put to practical use. Specifically, the measurement of the aggregate size is performed by continuously measuring the amount of aggregate passing through a certain point for each elapsed time as the absorbance, and obtaining a relationship curve between the elapsed time and the absorbance. The elapsed time can be converted to the size of the aggregate based on Stokes' law, and the absorbance will represent the size distribution of the aggregate. One example of this measurement curve is shown in FIG. 1. Using this measurement curve, the Stokes-equivalent diameter of the carbon black aggregate size is calculated by K using the following equation.

[0012]

(Equation 2) In this formula, d is the Stokes equivalent diameter of the aggregate
(nm), t is the elapsed time required for the sedimentation of the aggregate, and K is a constant determined by the measurement conditions.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the case where the horizontal axis represents a numerical value representing the size of an aggregate obtained by this measuring method with natural logarithm as a base, and the vertical axis represents the absorbance, that is, the distribution amount of the aggregate size, As shown in FIG. 1, it has been confirmed that this distribution curve shows a lognormal distribution. This figure 1
In the measurement curve, the time required to reach the maximum absorbance Ap is defined as Tp, and the time required to reach 50% of Ap, that is, the absorbance corresponding to 50% of the maximum absorbance, is Tn and Ts.
Then

In FIG. 2, the Stokes equivalent diameter of the carbon black aggregate converted by the equation (2) is Dst (mode),

(Equation 3) as well as

(Equation 4) It corresponds to. Here, Tn <Ts. Here, the aggregate size index of carbon black is

(Equation 5) Is defined by

The maximum frequency Stokes diameter of carbon black is usually a value at the time of showing the maximum value in the aggregate size distribution curve, but it is equivalent to the average value if the distribution curve is assumed to be close to a normal distribution. , And is displayed by Dst (mode) in FIG. Therefore, if this Dst (mode) is large, the particle size of carbon black tends to be large, and a rubber containing such carbon black tends to exhibit high rebound resilience but decrease wear resistance.

For this reason, in the case of ordinary commercial carbon black, the dynamic characteristics represented by rebound resilience tend to be proportional to Dst (mode), while the wear resistance tends to be inversely proportional to Dst (mode). However, it is almost impossible to achieve both rebound resilience and abrasion resistance only by controlling the size of Dst (mode), and when the aggregate size is evaluated by centrifugal sedimentation analysis, the maximum frequency of the aggregate A Dst
(mode) values and their distribution, usually as shown in Figure 2.

(Equation 6) One of the values in relation to the value evaluated in

When Equation 3 becomes large,

Since the numerical value of the expression (4) also increases, it is impossible to evaluate how the distribution has changed with respect to the representative value Dst (mode) in the present invention in the original sense.

In order to solve this problem, for example,
No. 62-129324, JP-A-63-301243, mixing several types of carbon blacks with different performances, and blending such a mixed carbon black into rubber to exhibit the desired performance. It is almost impossible and not practical to obtain carbon black that meets all requirements such as workability in the compounding process, workability of rubber products, and vulcanizability.

For this reason, the present inventors have discussed the effect of aggregate size on the dynamic properties of a rubber composition blended with a single product of carbon black. The aggregate size larger than the most frequent aggregate size was described above. Experimentally confirming that it is an important factor to solve the conflicting condition of simultaneously improving both rebound resilience and wear resistance,

The problem was solved by introducing the numerical value Z defined by the following equation. The reason for introducing the factor Z here is that when the logarithm of the equivalent diameter D obtained by the Stokes equation of the carbon black aggregate distribution (bottom is the natural logarithm e) is the vertical axis, and the absorbance is plotted on the horizontal axis, As shown in FIG. 1, the frequency distribution curve becomes a distribution curve substantially similar to a lognormal distribution. But Figure 2
As shown

(Equation 7) The pattern of the frequency curve cannot always be specified only by the magnitude relation of the values of. The reason is that the probability density function of a normal distribution is generally

(Equation 8) And the pattern of the frequency distribution curve depends on the value of the standard deviation. Therefore, in order to determine the pattern of the frequency distribution curve, it is necessary to introduce a standard deviation or a similar factor.

In order to solve this problem, the Dst (mode) value which is the most frequent aggregate size value and the aggregate size larger than the Dst (mode) value and the Dst (mode) is 50
Aggregate size value with% frequency value

By limiting the aggregate size distribution index Z calculated from the two values defined by the following equation to a certain range in relation to the nitrogen adsorption specific surface area (N ₂ SA) of carbon black, the tire tread portion In the so-called hard carbon black having a relatively large specific surface area used for
High abrasion resistance can be imparted while maintaining the rebound resilience of the conventional carbon black of the same grade, while the so-called soft carbon black used for tire carcass and automobile parts has the same It has been found that high reinforceability and good extrusion characteristics can be imparted to a rubber product containing such carbon black while maintaining the rebound resilience of carbon black.

The present invention makes use of the fact that the natural logarithm and absorbance of the carbon black aggregate, that is, the appearance frequency of the carbon black aggregate shows a substantially normal distribution, as described above, and uses Dst (mode) and Dst (mode).

The basis of the present invention is to introduce a completely new concept of evaluating the distribution state by defining the aggregate distribution index Z having a meaning close to the standard deviation of the distribution using the numerical value of Therefore, the introduction of Z has provided a standard for judging the shape of the distribution for the first time. By defining this evaluation criterion Z, simply

It can be evaluated that even if the value of [Expression 7] increases, the value of Z, which is the relationship with Dst (mode), decreases on the contrary. Here, "has a meaning close to the standard deviation of the distribution" means that the geometric mean diameter in the general formula of the lognormal distribution is Dst (mode) if the distribution is perfectly symmetric.
Since the distribution curve is not perfectly symmetrical, it uses the mode value Dst (mode) that gives the most frequent value, which is a representative value indicating the other central value, and the standard deviation This is because only one distribution curve on the side larger than Dst (mode) is used because the distribution curve to be evaluated is not completely symmetric.

Here, the calculation method for introducing the factor of Z will be briefly described as follows.
Now, assuming that the aggregate distribution of carbon black is a lognormal distribution, the probability density function is expressed as F (d)
The following expression is obtained when expressed by.

[0021]

(Equation 9) Here, the coefficient in the equation is A, and the measured value d is the geometric average value d.
The probability density function F (dg) when g is obtained is as follows.

[0022]

(Equation 10) F (dg), that is, A indicates the maximum value in this density function. Here, if the measured value at the point where F (d) becomes 0.5 A is dz, the following expression is obtained.

[0023]

[Equation 11]

When both sides of this equation are divided by A and the logarithm is taken, the following equation is derived.

[0025]

(Equation 12)

(Equation 13) here

In comparison with FIG. 2 and FIG. 2, the most frequent value Ap of the distribution, which is another representative value, is given instead of dg, and the Stokes diameter Dst (mode) and the side larger than Dst (mode) are given. And the Stokes diameter that is 50% of the maximum frequency

Then, dg is approximately equal to Dst (mode), and dz is approximately

And again

Since can be regarded as approximately Z,

## EQU1 ## is defined.

When the present inventors examined the relationship between the Z value and the nitrogen adsorption specific surface area of many commercially available carbon blacks, they all fell out of the range of this relational expression. For example, the so-called hard carbon black used for tire treads cannot satisfy the condition of reciprocity of resilience and abrasion resistance, and is used for applications other than tire treads, for example, for automotive parts The resulting carbon black does not balance both reinforcement and extrusion properties.

In the present invention, by limiting the aggregate distribution index Z to a certain range in relation to the nitrogen adsorption specific surface area of carbon black, the aggregate distribution index Z can be compared with carbon black having substantially the same nitrogen adsorption specific surface area and DBP absorption amount. In the case of carbon black for tire treads, that is, so-called hard carbon black, it is possible to greatly improve wear resistance while maintaining the same level of rebound resilience, and in carbon blacks other than tire tread applications, Extrusion characteristics can be improved while maintaining the same level of reinforcement. In other words, it is easy to produce carbon black that has both abrasion resistance and rebound resilience for hard carbon black and carbon black that has both reinforcement and extrusion properties for soft carbon black. Becomes possible.

[0028]

An example of the production of carbon black of the present invention is shown below. In the production of carbon black by the oil furnace method, fuel is generally introduced into a cylindrical carbon black production apparatus in the axial direction or tangential direction and burned. The hydrocarbon raw material is sprayed into the high-temperature gas flow while moving the combustion gas flow to the reaction zone, and a carbon black production reaction is caused by incomplete combustion of the raw material oil, and the carbon black suspension thus obtained is obtained. The reaction is stopped by rapidly cooling the gas flow, and the carbon black is recovered by passing through a collecting device such as a cyclone or a bag filter. The amount of heat required to convert the hydrocarbon feedstock sprayed into the production equipment into carbon black is unavoidably supplied by partial combustion of the hydrocarbon feedstock, but most of it is due to the heat of combustion of the fuel. Replenished.

The apparatus for producing carbon black used in the present invention basically follows this configuration, but has the following features. That is, the gaseous hydrocarbon material or the liquid hydrocarbon material can be used in the same combustion chamber, and is completely burned in a space outside the carbon black production reaction system. A two-fluid burner 1 having both an oxygen-containing gas introduction hole and a fuel introduction hole having a central axis at a tangential position on the front surface of a combustion chamber, By installing at least two independent fuel fluid introduction holes 3, 4 separate from the burner, and introducing an oxygen-containing gas into the fuel introduction holes to make the flow directions different from the fuel fluid, It is configured such that the mixing efficiency is remarkably improved and complete combustion of the fuel can be achieved at the time of introducing the hydrocarbon feedstock.

The production apparatus according to the present invention further comprises at least two or more oxygen-containing gas and / or fuel fluid introduction conduits 5, 6 in addition to the fuel fluid introduction holes 3, 4 in the first half of the carbon black production reaction chamber. , 7,8,9,10 are provided so that the adjustment of the aggregate size distribution of carbon black can be easily controlled by changing the introduction ratio and speed of each fluid into the conduit. The device of the present invention will be described in detail. As shown in FIG. 3, a cylindrical shape having an inner diameter of 450 mm and a length of 300 mm is fixed to a central portion of the cylinder by a guide with a water-cooling jacket installed in the axial direction. Fluid burner 1
A combustion chamber 2 having a central axis in the tangential direction installed in the first half of the combustion chamber, two first oxygen-containing gas introduction holes 3 and 4 having an inner diameter of 100 mm, and the first oxygen-containing gas Six radial second fuel introduction holes having an inner diameter of 25 mm and / or oxygen-containing gas introduction holes 5, 6, 7, 8, 9, and 10 are provided independently of the gas introduction holes. The fuel introduction hole and / or the oxygen-containing gas introduction hole have a structure as shown in FIG.

The oxygen-containing gas and the fuel fluid are introduced into the combustion chamber 2 in different introduction directions and as independent flows.
This difference in flow direction and independence significantly enhances the mixing efficiency of the oxygen-containing gas and the fuel fluid, improves the combustion rate, and contributes to the adjustment of the aggregate size distribution. Further, the fuel fluid introduced from the fuel fluid introduction hole adjacent to the oxygen-containing gas introduction hole is effectively mixed with the oxygen-containing gas, and the fuel fluid introduced from the fuel fluid introduction pipe downstream in the swirling direction while burning is burned. And promote complete combustion of the fuel fluid in a short time due to the flame propagation effect.

With such a structure, the combustion chamber 2
Since the complete combustion of the fuel is completed at the front of the combustion chamber without making the size of the fuel fluid too large, the number of fuel fluid introduction holes and the amount of the fuel fluid introduction should be adjusted according to the fuel and the material type having various characteristics and the amount of the introduction. Can be easily changed, the fuel load factor in the combustion chamber 2
(The amount of heat generated per unit volume) can be easily controlled, and this is also effective in adjusting the aggregate size distribution.
Further, the apparatus used in the present invention is connected to the combustion chamber.
A reaction zone 11 having a Venturi portion having a narrowest inner diameter of 0 mm and a length of 255 mm, and an upstream side of the Venturi portion, that is, a narrow diameter converging portion, is arranged in the forward direction with respect to the turning direction of the first oxidizing gas introduction hole. Through the upper and lower ends of the same cross section provided so that it can be introduced in the direction (tangent) or in the opposite direction (reverse tangent), 12, 13, 14, 15 in FIG.
At least two sets of second oxygen-containing gas and / or raw material introduction holes having an inner diameter of 40 mm, and one set of the first 40 mm inner diameter shown by 16 and 17 in FIG. 6 installed in the rear reaction zone 18 of the venturi section. 3 oxygen-containing gas and / or raw material introduction holes are installed,
Inner diameter 50 in which cooling water injection spray introduction holes 21, 22, 23, 24, 25, 26, 27 are installed in the reaction end zone 19 downstream of these third introduction holes.
It consists of a reaction continuation area of 0 mm and length of 400 mm, and the whole is covered with refractory. The rear part of the reaction end zone 19 is connected to the connecting pipe 20.
To a collection device (not shown) such as a bag filter.

In the present apparatus, in order to facilitate the adjustment of the aggregate size distribution, the material introduction holes and / or the oxygen-containing gas introduction holes in the venturi reaction zone and the rear reaction zone are inserted and withdrawn by providing a heat insulating jacket. Is mounted in a freely adjustable structure, and the cooling water press-in sprayer is also configured to be freely inserted and withdrawn. Supply and supply of oxygen-containing gas and fuel in the combustion chamber
The nitrogen-containing specific surface area is adjusted by appropriately adjusting the supply conditions and the turning direction of the oxygen-containing gas and / or raw material from the introduction hole of 3, and the like.
Carbon blacks having different (N ₂ SA), structure (DBP, 24M ₄ DBP), toluene coloring transmittance, specific coloring power, aggregate most frequent value, and aggregate size distribution index Z were produced. More specifically, the nitrogen adsorption specific surface area (N ₂ SA) and the control of the iodine adsorption amount are adjusted by the ratio of the feed oil introduction amount and the introduced oxidizing gas amount to increase the nitrogen adsorption specific surface area (N ₂ SA) or When decreasing the particle size, increase the amount of oxygen-containing gas introduced.On the other hand, when decreasing the nitrogen adsorption specific surface area (N ₂ SA) or increasing the particle size, decrease the amount of oxygen-containing gas introduced and control. did.

The control of the specific coloring power, 24M ₄ DBP, the aggregate size distribution and the Z value is mainly controlled by the flow state in the reaction chamber 11, that is, the introduction amount of the oxygen-containing gas introduced into the reaction chamber, especially the No. 2 and 3 introduction holes. Nos. 5, 6, 7, 8, 9, and 10 installed in the combustion chamber 2 and the oxygen-containing gas and / or fuel oil introduced from the introduction holes and the No. 5 installed in the Venturi section reaction zone 11.
12, 13, 14, 15 The amount of oxygen-containing gas or feed oil introduced from the inlet and the amount of oxygen-containing gas or feed oil introduced from Nos. 16, 17 installed in the venturi rear reaction zone (reaction chamber) 18 are Performed by adjusting. No. 12, 13, 14, 15
The positions of the introduction holes are schematically shown in the reaction zone.
It can be set at any position in the venturi section of No. 11, and the effect of this flow change is particularly significant by installing any of the inlet holes No. 12, 13, 14, and 15 in the narrowest part of the venturi. This is remarkable when oil is introduced.

In addition to simply adjusting the oxygen-containing gas amount, the aggregate size distribution and Z value can also be increased by adjusting the fuel supply amount from the No. 5-10 inlet to increase the stirring effect in the venturi section. The value can be adjusted. That is, when the fuel supply amount increases, the stirring effect becomes remarkable because the flow velocity and the gas density in the Venturi reaction zone increase, and such a method is also effective for adjusting the aggregate size distribution and the Z value. Means. In addition to this, the feed position of the feedstock is also a major control factor. That is, when the feedstock is introduced at a location near the entrance of the venturi, the feedstock is introduced in a state where the flow velocity and density of the combustion gas in the venturi are increased, and the aggregate size distribution is also increased by such means. And, when the value of Z moves to the smaller side, and when the introduction of the feedstock is moved to the downstream side of the Venturi reaction zone, the stirring effect becomes insufficient, so that the aggregate size distribution and the Z value tend to increase. There is. However, the feed hole for the feedstock oil is not limited to one location, and it can be divided and introduced from several locations, and the same applies to the oxygen-containing gas to be introduced as a secondary component. Therefore, the “feedstock main introduction position” shown in Tables 1 and 2 refers to the position of the forefront introduction hole in the production furnace. In addition, at least two inlet pipes 16 and 17 for introducing the oxygen-containing gas and / or the fuel fluid are provided in the first half of the rear chamber 18 of the venturi, and this inlet pipe has a final toluene color permeability. The main purpose of this is to adjust the flow rate so that if only the oxygen-containing gas is introduced from this introduction pipe under normal reaction conditions, an unexpected oxidation reaction will rapidly occur.

The adjustment of the aggregate size distribution and the Z value can also be performed by adjusting the cooling water press-in spray position in the reaction continuation and rapid cooling chamber 19. That is, if the spray position is set to the front of the furnace, the reaction chamber area will be reduced, and if the spray position is moved to the rear of the furnace, the reaction chamber area will be enlarged. Further, it is empirically known that the aggregate size distribution and the Z value can be adjusted by the cooling water injection amount. That is, when the amount of cooling water increases, the temperature of the reaction gas decreases, and as a result, the amount of reaction gas decreases, but on the other hand, the amount of water vapor generated due to the introduced water increases. It can be achieved by various adjustments.

As the feedstock, specific gravity (15/4 ° C.) 1.130, kinematic viscosity 16.8 cSt (50 ° C.), residual carbon 9.5%, initial boiling point 202 ° C., BMC1 (correlation index of the U.S. Department of Mines A hydrocarbon raw material having a property of 160 (highly aromatic) was used. As the fuel oil, a light hydrocarbon raw material having a specific gravity (15/4 ° C.) of 0.980, such as naphtha or kerosene, was used. But,
The feedstock oil and fuel oil are not limited to those having the properties listed here, and the feedstock oil is a petroleum distillation residue oil and a pyrolysis residue oil, and the fuel oil is the feedstock oil or natural gas or the like. Can be freely selected and used by the producer. Tables 1 and 2 show the production conditions of various carbon blacks produced under the above-mentioned carbon black production conditions using the above-mentioned raw material oil and fuel oil, and the properties of carbon black produced under these conditions. The carbon black aggregate size was measured by sedimentation analysis using a Disk Centrifuge manufactured by Joyce Loebl in the UK under the following measurement conditions and procedures.

In the case of a soft carbon black, 0.05 to 0.1% carbon black is added to a 30% aqueous methanol solution to which a slight amount of a nonionic surfactant is added, and the dispersion is completely dispersed by ultrasonication. Is used as a measurement sample. Disk
Pour 15 ■ 30 ml of a 25% by volume glycerin aqueous solution into the Centrifuge as a spin solution, and rotate the rotating disk at 6000 rpm.
Then, 0.1 ■ 0.5 ml of pure water is poured to form a buffer line by a conventional method, and then 0.2 ■ 0.3 ml of the above carbon black dispersion sample solution is poured. The recorder is activated simultaneously with the addition of the dispersion, and the amount of carbon black aggregate passing through a certain point near the outer periphery of the rotating disk by settling is optically recorded, and the amount is recorded as a histogram with respect to time. On the other hand, in the case of hard carbon black, the rotation speed of the rotating disk is set to 8000 rpm, and the carbon black dispersion
0.02 ■ 0.03 ml.

The Stokes equivalent diameter d is calculated as follows. This analyzer optically measures the amount of carbon black aggregate passing through a certain point near the outer periphery of the disk by settling down by dropping a sample solution onto a rotating disk as absorbance, and this measured amount is a continuous curve against time. As shown in FIG. From the settling time

When converted into the Stokes equivalent diameter by Equation 2, a corresponding curve of the carbon black aggregate equivalent diameter and its frequency (several luminous intensity) is obtained as shown in FIG. The sedimentation time is converted into a Stokes equivalent diameter by the following equation to obtain a histogram of the Stokes equivalent diameter of the carbon black aggregate and its frequency. Stokes diameter given by centrifuge analysis
d (nm) is given by the following equation.

[0040]

[Equation 14] In this equation, η is the viscosity coefficient (centipoise) of the carbon black suspension dispersion liquid for measurement, R is ln (R ₀ / R ₁ ), where R ₀ is the distance (mm) from the center of the rotating disk to the measurement point. )
The distance R ₁ until precipitation starting point from the rotating disk center (m
m), N is the number of revolutions (rpm) of the rotating disk, ρp is the density (g / cc) of the carbon black for measurement, that is, ρ = 1.86.
To

(Equation 15) Is the density (g / cc) of the carbon black dispersion liquid for measurement, t
Represents the time (minutes) required for sedimentation, and d represents the Stokes equivalent diameter (nm). However, assuming that the measurement temperature of the carbon black suspension, the number of rotations of the disk, and the amount of the dispersion liquid are constant, each term except for t is a constant.

When defined as

## EQU2 ## is obtained.

For example, when the spin solution is 25 ml of a 25% by volume glycerin aqueous solution, the measurement temperature is 25 ° C., and the rotation speed of the rotating disk is 6000 rpm, the value of K is 792.0. In addition, 17.5 ml of distilled water was poured as a spinning solution, the measurement temperature was 20 ° C., and the rotation speed of the rotating disk was 8,000 rpm.
It becomes 5. Therefore, Dst in Table 1 is Dst (mod
e) and

数 in FIG. 2

[Equation 3] and

Calculated from

Where:

[Equation 17] Required by Note that

Equation 3 is

(Equation 18) Given by Other carbon black test methods were as follows. (1) JIS K6221-1982 for each item of iodine adsorption amount, DBP absorption amount, specific coloring power, and toluene coloring transmittance. (2) Regarding the nitrogen adsorption specific surface area, method B of ASTM D3037-88. (3) For 24M ₄ DBP, ASTM D3493-88.

[0039]

[Table 1]

[0040]

[Table 2]

Rubber was compounded with carbon black using a Banbury mixer according to the compounding recipe shown in Table 3, and a measurement test of the obtained rubber composition was carried out under the measuring conditions shown in Table 3. The results are shown in Tables 4, 5 and 5. See Figure 6.

[0042]

[Table 3]

[0043]

[Table 4]

[0044]

[Table 5]

[0045]

[Table 6]

(1) Table 1 shows the relationship between the production conditions and the Z value for various grades of carbon black.
5,9,13,17,21 are cases where the Z value is within the specified range.The condition is that the ratio of the amount of air introduced into the combustion chamber to the amount of air introduced into the reaction chamber is large first, and then the reaction chamber is introduced. This is achieved by making the air supply position as forward as possible and introducing a large amount of air. In Example 2, when the fuel supply amount was increased, in Example 6, when both the feed oil and the fuel were increased, in Example 10, the feed oil was introduced from the more upstream side without changing the feed oil and the fuel supply amount. In the case of Example 14, when the feedstock is introduced from a more upstream side after increasing the fuel supply amount,
Example 18 increases the feedstock supply amount and introduces the feedstock from the more upstream side.Example 22 increases the feedstock oil and the fuel supply amount, and introduces the feedstock from the more upstream side. In this case, as apparent from these examples, the Z value can be limited to a certain range by introducing the feedstock oil into the reaction zone in the furnace where the gas flow rate and the density are high.

On the other hand, Comparative Examples 3, 7, 11, 15, 19, and 23 are examples in which the Z value exceeds the upper limit of the specified range. In this example, the amount of air introduced into the combustion chamber and the amount of air introduced into the reaction chamber are compared. The ratio is small compared to the corresponding example, that is, the total air amount is the same, but the amount of air introduced into the reaction chamber is smaller than that of the example, and a small amount of air is almost uniformly discharged from all the reaction chamber introduction holes. This is the case when introduced. On the other hand, if the amount of air introduced into the reaction chamber was further reduced and air was introduced from the rear of the reaction chamber, the Z value was significantly reduced as shown in Comparative Examples 4, 8, 12, 16, 20, and 24, and the specified value was reduced. You will fall outside the lower limit.

(2) Next, the relationship between the Z value and the rubber compounding characteristics is shown in Table 2. Natural rubber compounding, SBR1500 rubber compounding, SBR1
Examples 712 and 2 of hard carbon blacks (N220 grade and N351 grade) in which the Z value is within the specified range in 712 rubber compounding
5 and 6, it can be seen that the abrasion resistance has been greatly improved while maintaining the same level of rebound resilience. In general, the hysteresis characteristic of rubber represented by rebound resilience is inversely proportional to the abrasion resistance, but improvement of only one of these characteristics could be easily achieved by the prior art.
In addition, as an index of the reinforcing property of a rubber compound, a 300% modulus is generally cited, but it is known that when the 300% modulus increases, the abrasion resistance also tends to increase. As a condition for satisfying the abrasion compatibility effect, it is necessary to evaluate the relationship between rebound resilience and abrasion resistance under a condition where the 300% modulus is almost constant.

On the other hand, in Comparative Examples 3 and 7 in which the Z value exceeds the specified range, the improvement of the rebound resilience was observed in any of the rubber compositions, but the abrasion resistance was reduced to the level of a normal product as a control product. Have not been able to maintain. Also Z
In Comparative Examples 4 and 8 in which the value is equal to or less than the lower limit of the specified range, the improvement of the reinforcing property, that is, the improvement of the abrasion resistance can be maintained, but the rebound resilience is reduced, and the abrasion resistance and the hysteresis characteristic are traded off. Can not be satisfied.

Also, so-called soft varieties N550 and N66
Examples for 0, N762, N754 grade products are 9.10,13,14,17,18,2
In 1,22, it is possible to improve the reinforcing properties represented by the 300% modulus and tensile properties of each rubber compound composition while maintaining the rebound resilience at the same level as the conventional product of the control product,
In addition, the extrusion properties of EPDM rubber compounding compositions can be significantly improved. On the other hand, Comparative Examples 11, 15, 19, and 23 are examples in which the Z value exceeds the upper limit of the specified range of the following formula, and the reinforcing properties such as tensile strength cannot be maintained at the level of the conventional control. Unlike the hard varieties, the soft varieties are characterized by a greater contribution of the Z value to the reinforcing properties. Comparative Example 1
Samples Nos. 2, 16, 20, and 24 have Z values below the lower limit of the range defined by the following formula, but the extrusion properties are deteriorated although the improvement of the reinforcing properties such as tensile strength can be maintained. 0.385− (0.0005 × N ₂ SA) ≧ Z
≧ 0.218− (0.0005 × N ₂ SA)

When controlling the above Z value, Z
In order to remarkably improve the desired rubber compounding characteristics by decreasing the value, it is necessary to consider the relationship between carbon black and other physicochemical characteristics other than the Z value. For example, for soft carbon black,
It is necessary to design the production conditions so that the toluene coloring transmittance specified in JIS K6221 6.2.4 is at least 30% or more and less than 75%. By limiting the degree of toluene coloring to such a range, the vulcanization properties of the compounded rubber composition, for example, Mooney scorch time, can be shortened, and as a result, mold flow during rubber product molding can be prevented, and in the vulcanization step, Workability can be improved. However, if the toluene coloring transmittance does not reach 30%, the contamination of the compounded rubber becomes large, which results in an undesirable result.
On the other hand, in the hard carbon black, lowering the toluene coloring transmittance results in a disadvantage that the Mooney scorch time is shortened and a burning phenomenon of the vulcanized rubber occurs, so that at least 75% or more can be maintained. It is necessary to design the manufacturing conditions.

Next, the ratio between the iodine adsorption amount and the nitrogen adsorption specific surface area
(IA / N ₂ SA) needs to be between 0.90 and 1.10, and it is necessary to design the manufacturing conditions so that such limited requirements can be cleared. Since the iodine adsorption amount uses iodine with a high molecular weight as the adsorption medium, an abnormally low value may be given if the carbon black surface is significantly contaminated with tar-like undecomposed substances. Compounding carbon black with a small nitrogen resting specific surface area ratio (IA / N ₂ SA), especially hard carbon black with a small particle size, to rubber can easily cause burning and cause poor dispersion. is there.

On the other hand, the ratio between the iodine adsorption amount and the nitrogen adsorption specific surface area
Carbon black with a large (IA / N ₂ SA) has a small nitrogen adsorption amount due to insufficient development of the carbon black microstructure, or iodine is adsorbed on the carbon black surface due to abnormal surface properties. It is considered to be caused by wear due to factors other than the above, and if such carbon black is blended with rubber, the bonding with rubber becomes insufficient, which leads to deterioration of reinforcing property and is not preferable. is there.

[0054]

[Brief description of the drawings]

FIG. 1 is an example of a measurement curve showing the relationship between elapsed time and absorbance when carbon black aggregate is measured by centrifugal sedimentation analysis.

FIG. 2 is a plot of the relationship between the logarithm of the Stokes equivalent diameter of the aggregate and the frequency value in the curve shown in FIG. 1;

FIG. 3 is a longitudinal sectional view showing an example of an apparatus used for producing carbon black of the present invention.

FIG. 4 is an enlarged sectional view of a portion A in FIG. 3;

FIG. 5 is an enlarged sectional view of a portion B in FIG. 3;

FIG. 6 is an enlarged sectional view of a portion C in FIG. 3;

[0055]

[Explanation of symbols]

 1 Two-fluid burner 2 Combustion chamber 3,4 Oxygen-containing gas introduction hole 5 ■ 10 Oxygen-containing gas and / or fuel introduction hole 11 Venturi reaction zone 12 ■ 17 Oxidizing gas and / or raw material introduction hole 18 Rear reaction chamber 21 ■ 27 Cooling water injection spray introduction hole 19 Reaction continuation and cooling water injection zone 20 Rear connection pipe

(Equation 16)

Claims (1)

[Claims] 1. A carbon black having a nitrogen adsorption specific surface area (N ₂ SA) and an aggregate size distribution index Z in a range defined by the following formula. 0.385+ (0.0005 × N ₂ SA) ≧ Z ≧ 0.218− (0.0005 × N ₂ SA) Here, Z is a value defined by the following equation. (Equation 1)