JP3506004B2 - 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 carbon black used for various applications such as filling materials, reinforcing materials, conductive materials and coloring pigments.

[0002]

BACKGROUND OF THE INVENTION Carbon black is widely used as a pigment, a filler, a reinforcing pigment and a weather resistance improver. The production method is generally in the first reaction zone of a cylindrical carbon black production furnace in the axial direction of the furnace. Alternatively, the oxygen-containing gas and the fuel are introduced in a tangential direction, and the high temperature combustion gas flow obtained by combustion of these is continuously moved into the second reaction zone installed in the axial direction of the furnace while moving in the gas flow. 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 the third reaction zone to stop the reaction is widely known.

Carbon black used as a colorant in resin colorants, printing inks and paints is required to have excellent blackness, dispersibility, gloss and tinting strength, and is mainly used as a reinforcing agent for automobile tires. The carbon black produced is required to have excellent abrasion resistance. Carbon black particles exist in a state where particles are fused together like dumplings stabbed on skewers, and individual spherical particles only characterize dumplings and peaks and valleys of dumplings. The particle size regarded as is closely related to the performance in various applications, such as the reinforcing property and the blackness. (Carbon Black Handbook, 3rd edition, I. General introduction, page 7).

The particle diameter is determined by taking a photograph of tens of thousands of times with an electron microscope having a resolution of at least 1.5 to 2 nm and directly measuring it. The particle size of carbon black usually refers to the particle size of carbon black measured in this way, but this particle size is in the range of 10 to 300 nm depending on the grade and belongs to the so-called aerosol or colloid region. . It is known that the blackness and tinting strength when carbon black is used as a black pigment largely depends on the particle size of carbon black, and the smaller the particle size, the higher the blackness. For example, the relationship between blackness and particle size is disclosed in Japanese Patent Laid-Open No. 50-68992. Further, it is known that such a carbon black having a small particle size exhibits a high degree of abrasion resistance when used as a reinforcing agent for a tire.

On the other hand, the particle size distribution also has a great influence on the tire tread rubber composition, which is required to have rubber properties, especially great abrasion resistance, and it is said that a narrower particle size distribution is more preferable. Generally, the smaller the average particle size, the narrower the distribution.

When carbon black is used as a black pigment, ultrafine carbon black having a particle size of 15 nm or less has a high blackness and is used in fields such as high-grade paints and high-grade resin colorants. This class of carbon black is manufactured by the channel method and is HCC (High Colo).
r Channel), manufactured by the furnace method is used for HCF (Hig
h Color Furnace).

Among the small particle diameters, ultrafine carbon black having a particle diameter smaller than 14 nm has a very high blackness and is used for the highest grade paint and the highest grade resin coloring. The products manufactured by occupy all the commercial products. This is because, in the channel method, it is possible to produce ultrafine particles having a particle diameter of 13 to 14 nm and a sharp particle diameter distribution, which exhibits extremely high blackness. Particularly in the field of high-grade paints and high-grade resin colorants, carbon black that exhibits the highest degree of blackness tends to dominate the market.

In the furnace method, in order to obtain carbon black having a small particle size, first, a raw material hydrocarbon is sprayed into a high-speed gas flow in a choke portion provided in the second reaction zone, and the kinetic and thermal energy of the gas are sprayed. It is well known that it is effective to atomize liquid feedstock. It is also known that carbon black having a small particle size can be obtained by reducing the amount of raw material oil injected with respect to the amount of combustion gas. However, if the feed rate of the raw oil is reduced, the productivity of carbon black will decrease. It is well known that increasing the gas temperature in the feed oil injection region is effective for efficiently producing carbon black having a small particle size, as a method that does not reduce productivity. With respect to this, in the manufacture of furnace black, it is generally made to raise the temperature of the carbon black generation region by leaving some residual oxygen in the gas of the feed oil injection portion and partially burning the feed oil itself. . However, in this method, a part of the injected raw oil is not used as carbon black but used in the combustion reaction, so that the yield is deteriorated.

With the conventional furnace technique, it is difficult to stably produce particles having a particle size of about 11 to 14 nm. Even if particles having a particle size smaller than that can be produced, the particle size distribution is It was not possible to exhibit the blackness equivalent to that of the channel Bunrak widely. Further, in order to obtain a small particle size, it is necessary to extremely reduce the amount of raw material hydrocarbons charged into the furnace with respect to the amount of combustion gas generated in the furnace, resulting in an extremely high product yield. Will result in a decline. Further, in order to obtain a high degree of blackness by the technique of the conventional furnace method, it is necessary to reduce the particle size and the DBP. Generally, as a method of lowering DBP, an alkali metal salt or a solution thereof is added to a feedstock oil or is introduced into a combustion zone or a reaction zone. In the case of blending in, the reduction of the particle size and the size of the agglomerate have a drawback of causing deterioration of dispersibility and fluidity.

Conventionally, regarding the carbon black produced by the furnace method corresponding to the channel black,
There are some reports. For example, Japanese Patent Publication No. 54-7632 discloses a method in which a raw material hydrocarbon is vaporized and supplied into a furnace by using an EM average particle diameter (corresponding to the average particle diameter) of 9 nm, E
M particle size standard deviation 5.7 nm, BET specific surface area / EM specific surface area ratio of 1.25 carbon black, EM average particle size 14 nm, EM particle size standard deviation 5.5 nm, BET
It is described that a carbon black having a specific surface area / EM specific surface area ratio of 1.25 was obtained.

However, judging from the fact that the ratio of BET specific surface area / EM specific surface area is 1.3 or less, it is presumed that the proportion of polycyclic aromatic hydrocarbons is large, as will be described later, which is a safety problem. It is thought that there is.

On the other hand, although the channel method can produce carbon black having ultra-fine particles and high blackness, it is produced in an oxygen atmosphere, so that the production process itself has a drawback of low product yield and low productivity. There is. For example, "FW200" (trade name, manufactured by Degussa Co., Ltd.) is sold as a channel black having a small particle size manufactured by the channel method, and the particle size is set to 13 nm (catalog value). However, since the channel black obtained by such a channel method is manufactured in an oxygen atmosphere, the carbon black itself exhibits acidity. This has the following important drawbacks: That is, when (1) is blended with the resin, the obtained resin composition tends to deteriorate. (2) When compounded with rubber, the obtained rubber composition has poor abrasion resistance. (3) When an aqueous coating composition is prepared, carbon black easily aggregates in the coating composition. That is, it inherently has such a drawback.

On the other hand, unreacted polycyclic aromatic hydrocarbons remaining in carbon black have recently been pointed out to have a risk of carcinogenicity, and when carbon black as a product contains a large amount of them. It has come to be considered that there is also a problem with safety. Therefore, it has a blackness similar to that of channel black by the furnace method with good production efficiency, and has good dispersibility when compounded in paints and resins, and has a low proportion of unreacted polycyclic aromatic hydrocarbons in the product. It is required to produce various carbon blacks.

[0014]

As described above,
Regarding the relationship between the characteristics of carbon black and the physical properties of carbon black-containing compositions such as resin compositions, it is an important issue how to satisfy blackness, dispersibility, and safety which are generally in a reciprocal relationship. There is. Further, it is required that the rubber composition is excellent in abrasion resistance when it is blended with a rubber component, and that deterioration when it is a resin composition is suppressed. Moreover, once dispersed carbon black must not re-aggregate. An object of the present invention is to provide a carbon black having high blackness and good dispersibility, capable of preventing aggregation, and having high safety when various carbon black-containing compositions are prepared. Is.

[0015]

Means for Solving the Problems The present inventors have conducted various studies to obtain a carbon black having a small particle size, which is excellent in blackness and dispersibility, by a method excellent in safety and productivity. In particular, various studies were conducted on a method for producing carbon black by a furnace method, which has a blackness equal to or higher than that of channel black, and has good dispersibility and safety, and further can solve the drawbacks of channel black. It was As a result, the present inventors have found that the dispersibility of carbon black is affected by various physical properties of carbon black in addition to the particle size, and a representative value thereof is a pH value. That is, when the pH value is low, there are drawbacks such that the resin is often decomposed when mixed with the resin, and when it is used as a water-based paint, aggregation is likely to occur. Was found to contribute to.

Further, it was found that when the ratio of N ₂ SA / SEM specific surface area does not reach a specific value, the proportion of unreacted polycyclic aromatic hydrocarbons remaining in the carbon black is too large to be ignored. . It has been pointed out that polycyclic aromatic hydrocarbons have a carcinogenic risk in recent years, and it is considered that there is a problem in safety if the ratio of carbon black as a product is large. It is required to obtain carbon black that exhibits good characteristics while suppressing it. Further, the ratio of N ₂ SA / SEM specific surface area represents the degree of pore area on the surface of carbon black particles, but when this value does not reach a specific value, for example, the monomer is polymerized on the surface of carbon black. Then, it was found that the degree of surface treatment may be lowered in some cases, for example, when the surface treatment of carbon black such as grafting for polymer coating is performed, the degree of grafting is lowered. Also,
When used as a conductive black, the conductivity becomes low.
Further, when platinum or other metal is carried and used as a catalyst carrier, there is a drawback that the particle size of the catalyst becomes large and the activity becomes difficult to obtain.

That is, in order to obtain carbon black having high blackness, high dispersibility and high safety, pH and N ₂ SA / S are required.
The characteristics such as the ratio of the EM specific surface area also influence, and the present inventors have found that it is important to control these characteristics within a desired range. Furthermore, these p
Setting the balance of the H, N ₂ SA / SEM specific surface areas to a specific range keeps the abrasion resistance of the rubber composition high, prevents the resin composition from deteriorating, and prevents the agglomeration in the aqueous coating composition. They also found that it was important for prevention. Therefore, it has been desired to efficiently produce carbon black whose various characteristics are controlled.

Although Japanese Patent Publication No. 54-7632 described above describes carbon black having a BET specific surface area / EM specific surface area ratio of 1.3 or less, B
Regarding the ratio of ET specific surface area / EM specific surface area, there is no mention of the drawbacks when the value is too small, and there is no mention or suggestion of pH, which is an important characteristic that affects blackness together with particle size. Not.

As a result of further diligent studies, the present inventors have made a novel carbon black having an average particle size of 13 nm or less, a N ₂ SA / SEM specific surface area ratio of more than 1.3 and a pH value of 5 or more. It was found that this carbon black exhibits extremely excellent characteristics.

That is, according to the present invention, the average particle size is 13n.
m ₂ and the N ₂ SA / SEM specific surface area ratio is 1.3.
Carbon black having a larger pH value of 5 or more, a coating composition, a resin composition, a rubber composition, and an ink composition containing such carbon black.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The carbon black of the present invention has an average particle size of less than 13 nm. Particularly preferably, it is 8 to 12 nm. Particle size is 13
If it is more than nm, the blackness when used as a paint is not sufficient. Here, the average particle diameter refers to the average diameter of the particle diameters obtained by electron microscopy. The carbon black of the present invention further has a N ₂ SA / SEM specific surface area ratio of more than 1.3. When this ratio is 1.3 or less, there is a problem that the oxidation treatment is difficult. In addition, there is a correlation between this ratio and the proportion of unreacted polycyclic aromatic hydrocarbons remaining in the carbon black. If this ratio is 1.3 or less, the amount of polycyclic aromatic hydrocarbons can be ignored. Not desirable for safety. In the present invention, the ratio of N ₂ SA / SEM specific surface area is set to be larger than 1.3, preferably 1.5 or more, more preferably 1.8 or more. On the other hand, if this ratio is too large, the viscosity when the ink composition is prepared may increase or the dispersibility may be adversely affected. Therefore, it is usually desirable to set it to 2.8 or less, particularly 2.5 or less.

The ratio of N ₂ SA / SEM specific surface area is N ₂ S
A and SEM specific surface areas are obtained, and the ratios are calculated. N ₂ SA is measured by ASTM D3
Determine according to 037-88. The SEM specific surface area is calculated by the following formula. SEM = 6000 / (ρ ・ dA) ρ: Specific gravity of carbon black (1.86 g / cm ³ ) dA: Body area particle size (nm)

Further, the carbon black of the present invention has a pH of 5 or more. When the pH is less than 5, the resin composition is apt to deteriorate when such a carbon black is used, and the abrasion resistance is inferior when a rubber composition is prepared using such a carbon black. When an aqueous paint is prepared using such carbon black, there is a problem that the carbon black is likely to aggregate. Particularly preferably, it is 6 or more. The pH is measured according to JISK6
221-1982. As described above, the pH of channel black, which has hitherto been marketed as a carbon black having a small particle size and excellent blackness, is as low as less than 5 and usually less than 3 due to its manufacturing method.

The carbon black of the present invention satisfies both the blackness and the dispersibility by making the particle size, the ratio of N ₂ SA / SEM specific surface area and pH described above within a specific range, and further it is safe. It can also be excellent. In the present invention, the diameter of the aggregate is not particularly limited, but preferably D _mod is 80 nm or less, more preferably 4
It is set to 0 nm or less. The aggregate diameter is dispersibility as described above,
The role played by the blackness is gradually becoming clear, but in the present invention, a specific particle size and a specific N ₂ SA / S
Carbon black adjusted to have a ratio of EM specific surface area and a specific pH exhibits suitable characteristics in a range of D _mod of 80 nm or less, more preferably 40 nm or less.

By thus adjusting the particle size and the aggregate size within a specific range, it is possible to exhibit the excellent characteristics of simultaneously satisfying the blackness and the dispersibility. Further, by adjusting the ratio of D _1/2 / D _mod to 0.6 or less, preferably 0.55 or less, the blackness becomes extremely excellent and the dispersibility is improved. here,
D _1/2 / D _mod is the full width at half maximum D of the maximum frequency Stokes equivalent diameter in the aggregate Stokes equivalent diameter distribution obtained by the centrifugal sedimentation method.
Is the ratio of _1/2 and a maximum frequency Stokes equivalent diameter D _{mo d,} but carbon black this ratio is 0.6 or less, more ratio D ₇₅ / D _mod volume 75% diameter D ₇₅ and D _mod 1.
Carbon black having 6 or less can also be obtained.
In this product, the content of large agglomerate diameters exceeding 75% in volume, which adversely affects dispersion, is extremely low. That is, it is possible to efficiently obtain carbon black having a small particle size, a small aggregate size, a sharp aggregate size distribution, and few large aggregate sizes. Further, in order to obtain higher blackness, this carbon black has D _mod of 20 to 80 n.
The inventors have found that m and cDBP are preferably 50 cc / 100 g or less, and the inventors have found that they have succeeded in producing such carbon black.

Further, cDBP is preferably 50 cc / 100 g or more. cDBP is also called crushed DBP absorption number and is measured according to ASTM D-3493-88, but cDBP is 50 cc / 1.
When it is less than 00 g, the dispersibility is poor. The value of cDBP is particularly preferably 60 cc / 100 g or more.

The carbon black of the present invention described above has such excellent characteristics in terms of blackness and dispersibility. To efficiently obtain the carbon black of the present invention, the following method is used. Can be taken. In Figure 1,
FIG. 1 is a schematic longitudinal sectional view of an essential part of an example of a carbon black manufacturing furnace that can be used in the present invention.

The furnace has, along its length, a first reaction zone 1 for forming a high temperature combustion gas stream, and a first reaction zone 1 for mixing the obtained high temperature combustion gas stream with a raw material hydrocarbon to produce carbon black. 2 reaction zones 2 and a third reaction zone 3 downstream of the second reaction zone and stopping the reaction
It is divided into and. The process itself in each reaction zone can basically adopt the same method as the conventional technique. In the first reaction zone, fuel hydrocarbons and oxygen-containing gas are generally introduced from the combustion nozzle 5 to generate a hot gas stream. Air, oxygen or a mixture thereof is generally used as the oxygen-containing gas, and hydrogen, carbon monoxide, natural gas, petroleum gas and petroleum liquid fuels such as heavy oil and coal-based creosote oil are generally used as the fuel hydrocarbons. Liquid fuel is used.

In the second reaction zone, the raw material hydrocarbon is sprayed into the high temperature gas stream obtained in the first reaction zone from a raw material hydrocarbon introduction nozzle 6 provided in a cocurrent or lateral direction to thermally decompose the raw material hydrocarbon. Convert to carbon black. As the raw material hydrocarbon, benzene, toluene, xylene,
Aromatic hydrocarbons such as naphthalene and anthracene, coal-based hydrocarbons such as creosote oil and carboxylic acid oil, heavy petroleum oil such as ethylene heavy-end oil and FCC oil,
Acetylene-based unsaturated hydrocarbons, ethylene-based hydrocarbons, aliphatic saturated hydrocarbons such as pentane and hexane are preferably used.

The third reaction zone contains 1000 to 1000 of high temperature reaction gas.
In order to cool the liquid to 800 ° C. or lower, a liquid or gas cooling medium such as water is sprayed from the reaction stopping fluid introducing nozzle 7. The cooled carbon black can be subjected to a known general process such as separation and collection with a collection bag filter and the like. In the figure, 8 is a control valve.

In order to obtain the carbon black of the present invention, when the carbon black is produced using the above furnace, various conditions in the carbon black producing region in the furnace, including the conditions of the position where the raw material hydrocarbon is introduced, are appropriately set. It is preferably performed by adjusting. Specifically, the oxygen concentration in the combustion gas at the site where the raw material hydrocarbon is introduced is 3 vo
It should be 1% or less, preferably 0.05 to 1 vol%. Surprisingly, by reducing the oxygen concentration at the feed hydrocarbon introduction position as much as possible, a carbon black with such a small particle size, a small aggregate size, and a uniform large-particle aggregate was suppressed. They found that they could get a good yield.

To measure the oxygen concentration at the starting hydrocarbon introduction site, the gas at the starting hydrocarbon introduction site is sampled,
For example, with a gas chromatography measurement device, nitrogen, oxygen,
It can be determined by measuring carbon dioxide, carbon monoxide, hydrogen, methane, and acetylene. The water generated by combustion is not included in the calculation.

The temperature of the portion where the raw material hydrocarbon is introduced is 18
The temperature is preferably 00 ° C or higher, more preferably 1900 ° C or higher, and further preferably 2000 to 2400 ° C. This makes it possible to easily obtain carbon black having a small particle size, a small aggregate size, and a sharp aggregate distribution.

In order to bring the temperature of the portion into which the raw material hydrocarbon is introduced into the above range, oxygen can be added to the air when forming the high temperature combustion gas stream in the first reaction zone. Of course, the method of raising the combustion gas temperature is not limited to the addition of oxygen, and it is also possible to take a method of preheating air or the like. The temperature inside the furnace can be confirmed by means such as a radiation thermometer. The second reaction zone has a choke portion. The choke part is a part where the cross-sectional area is sharply narrowed. It is particularly desirable that the choke portion has a length of 800 mm or more, preferably 800 to 3000 mm. The present inventors have found that particularly in this range, the diameter of the aggregate of the obtained carbon black can be made particularly small.

The inlet of the choke portion, which is the starting portion of the choke portion, includes the narrowest portion of the flow passage, and the angle with respect to the axial direction in which the flow passage contracts exceeds 5 ° from 5 °.
It refers to the part that changes below. On the other hand, the outlet of the choke portion, which is the end of the choke portion, refers to a portion where the angle of the flow path with respect to the axial direction of contraction becomes a value exceeding 5 °. The diameter of the choke is preferably 170 mm or less. Particularly preferably 3
It is 0 to 170 mm, more preferably 50 to 150 mm. Within this range, a product having a particularly sharp aggregate distribution can be easily obtained. The faster the gas flow rate in the choke, the better. After the raw material hydrocarbon is introduced, it is atomized by the motion and thermal energy of the combustion gas, and the higher the speed of the combustion gas at that time is, the more preferable it is 250 m / s or more.
~ 500 m / s is preferred. Within this range, carbon black having a particularly small particle size and a small aggregate size and a narrow particle size distribution can be easily obtained.

Further, in order to uniformly disperse the starting hydrocarbon in the furnace, it is preferable to introduce the starting hydrocarbon into the furnace through two or more nozzles. The feed position of the raw material hydrocarbon is
It is preferable that the area within the choke portion is within 1 ms from the choke inlet on the basis of the average cross-sectional flow velocity of the combustion gas. The range is more preferably within 0.6 ms. By introducing at this site, carbon black having a particularly small particle size and a uniform aggregate size can be obtained. By combining these various conditions, it is possible to obtain a carbon black of a small particle size, which has a controlled pH and a ratio of N ₂ SA / EM specific surface area at a constant value, with good yield by the furnace method. The present inventors have found out what can be done. That is, the above-described production method makes it possible to obtain the above-described carbon black of the present invention, which has been difficult to produce conventionally.

By preparing the coating composition, the resin composition, the rubber composition and the ink composition containing the carbon black of the present invention described above, suitable characteristics can be exhibited in these various uses. As described above, the carbon black of the present invention has extremely excellent dispersibility in various vehicles and at the same time has an extremely high degree of blackness. Therefore, these various compositions also have extremely excellent characteristics. Of. Further, in the carbon black of the present invention, by setting the pH and the ratio of N ₂ SA / EM specific surface area to specific ranges, a rubber composition having excellent abrasion resistance can be obtained, and a resin composition which is resistant to deterioration can be obtained. Thus, it is possible to prevent the agglomeration in the aqueous coating composition. As described above, the carbon black of the present application, which can be obtained by mixing with various vehicles to obtain an excellent carbon black-containing composition, is a novel one which has not existed until now. It can be obtained easily.

In order to obtain the coating composition of the present invention, the resin composition of the present invention, and the rubber composition of the present invention, various known methods except that the carbon black of any of the present invention is contained. It can be employed to prepare the desired composition. When preparing a resin composition containing the carbon black of the present invention, the applicable resin is not particularly limited, for example, various thermoplastic resins or thermosetting resins, various additions such as a mixture of these resins or a filler. It may be a product added. Usually, the one used for preparing the resin composition may be appropriately selected and used according to the purpose.

The carbon black of the present invention is added to these resin components and kneaded as necessary. At this time, those commonly used as a rubber kneader, for example, a roll mixer as a batch type open type, a Banbury type mixer as a batch type closed type, a single screw kneading extruder as a continuous screw type, a twin screw kneading extruder, a continuous rotor. A single-screw kneader, a twin-screw kneader, or the like can be used as a formula. The content of carbon black may also be determined by employing a known technique, and generally 1 to 60% by weight is suitable.

In the case of preparing a coating composition containing the carbon black of the present invention, the varnish used is not particularly limited as long as it can be used in the coating, and for example, various oil-based coatings, alcoholic coatings, synthetic resins. The paint used may be one used for water-based paint, and the target paint is not particularly limited, and oil paint, oil enamel, phenol resin or maleic acid resin, alkyd resin paint, aminoalkyd resin paint, urea resin paint, alcohol Examples include paints, lacquers, vinyl resin paints, acrylic resin paints, polyester resin paints, epoxy resin paints, polyurethane resin paints, silicone resin paints, emulsion resin paints, and water-soluble resin paints. However, as described above, the carbon black of the present invention is excellent in the effect of preventing agglomeration particularly when the water-based coating composition is prepared, and therefore it was used for the preparation of the water-based coating composition such as the emulsion paint and the water-soluble resin paint. In this case, it is preferable because particularly high characteristics can be exhibited.

The content of carbon black may also be determined by employing a known technique, and generally 0.1 to 10% by weight is suitable. Further, in order to prepare the rubber composition containing the carbon black of the present invention, the carbon black of the present invention may be blended with at least one of natural rubber and synthetic rubber. Generally, the compounding amount in this case is 30 to 150 parts by weight of carbon black with respect to 100 parts by weight of rubber.
This makes it possible to obtain a rubber having a low loss coefficient and a small amount of heat generation. The rubber component used at this time is not particularly limited, and examples thereof include styrene-butadiene rubber, butadiene rubber, isoprene rubber, chloroprene rubber, nitrile butadiene rubber, isobutylene isoprene rubber, ethylene propylene rubber, silicone rubber, fluororubber, and chloro rubber as synthetic rubber. Sulfonated polyethylene, chlorinated polyethylene, polysulfide rubber, urethane rubber, acrylic rubber, epichlorohydrin rubber, propylene oxide rubber, ethylene-vinyl acetate copolymer, liquid rubber, polyalkylene sulfide, nitroso rubber and the like, of course, natural rubber, Alternatively, a mixture of these various types can also be used. Further, various kinds of additives can be blended if necessary.

The carbon black of the present invention is added to the above rubber component and kneaded to obtain a rubber composition. The kneader may be one normally used as a rubber kneader, and examples thereof include a roll mixer, a Banbury type mixer, a continuous screw type or continuous rotor type single-screw kneading extruder, and a twin-screw kneading extruder. The ink composition of the present invention is not particularly limited except that the carbon black of the present invention is used. That is, it is mixed with various conventionally known varnishes and solvents and sufficiently dispersed. The carbon black of the present invention is excellent especially when used as an aqueous ink composition. For example, a known means such as dispersing the varnish in an aqueous medium together with various water-soluble varnishes such as an alkali-soluble type resin and a hydrosol type resin may be adopted. The dispersion method is not particularly limited. Further, as a dispersion method, various known methods may be used, and various additives may be added.

[0043]

EXAMPLES The present invention will be described in more detail below with reference to examples. (Examples 1 to 4) First reaction zone including an air introducing duct and a combustion burner shown in FIG. 1, an inner diameter of 60 m connected to the first reaction zone and having a plurality of raw material nozzles penetrating from the periphery
m, the second reaction zone having a choke part with a length of 1000 mm, an inner diameter of 100 mm equipped with a quench device, a length of 6000
A carbon black production furnace having a structure in which the third mm reaction zone was sequentially connected was set up.

The position of the raw material nozzle is 100 mm from the entrance of the choke section. Using the above furnace, carbon black having the physical properties shown in Table 1 was produced by adjusting the combustion gas temperature, the combustion gas oxygen concentration, and the raw material supply amount at the raw material hydrocarbon introduction position. Creosote oil was used as a fuel and a feedstock hydrocarbon. Oxygen was added to the air introduced from the air introduction duct in the first reaction zone, and a high temperature atmosphere of 1900 ° C. or higher was maintained at the starting hydrocarbon introduction position. The following test methods were used to determine the physical properties of carbon black in Table 1.

(Average particle size) By electron microscopy. Electron microscopy is the method described below. Carbon black is put into chloroform and ultrasonic waves of 200 KHz are applied for 20 times.
After irradiating and dispersing for a minute, the dispersed sample is fixed on a support film. This is photographed with a transmission electron microscope, and the particle diameter is calculated from the diameter on the photograph and the magnification of the photograph. This operation is performed about 1500 times, and it calculates | requires by the arithmetic mean of those values.

(N ₂ SA Specific Surface Area) The N ₂ SA specific surface area was determined according to ASTM D3037-88.

(SEM Specific Surface Area) The SEM specific surface area was calculated by the following formula. SEM = 6000 / (ρ ・ dA) ρ: Specific gravity of carbon black (1.86 g / cm ³ ) dA: Body area particle size (nm)

(CDBP) Crushed DBP absorption number (cDB
P) was determined according to ASTM D-3493-88.

(D _mod , D _1/2 ) Maximum frequency Stokes equivalent diameter (D _mod ) and Stokes equivalent diameter _half- value width (D _1/2 )
Was determined as follows. Using a 20% ethanol solution as the spin liquid, a centrifugal sedimentation type flow rate distribution measuring device (J
The Stokes equivalent diameter is measured by DC Automation Model 3 manufactured by L Automation Co., Ltd., and a histogram of the relative occurrence frequency in the given sample versus the Stokes equivalent diameter (FIG. 2) is created.
A line (B) is drawn from the peak (A) of the histogram parallel to the Y-axis to the X-axis and ends at the point (C) of the X-axis of the histogram. The Stokes diameter at the 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) intersects the histogram distribution curve at two points D and E. The absolute value of the difference between the two Stokes diameters at the two points D and E of the carbon black particles is the Stokes equivalent diameter _half- value width D _1/2 value.

(D ₇₅ ) 75% volume diameter (D ₇₅ ) was determined as follows. In the method of determining the maximum frequency Stokes diameter, a histogram of Stokes equivalent diameter vs. relative occurrence frequency of the sample is obtained from each Stokes diameter and frequency from FIG. 2, and the obtained Stokes diameter is the sample volume up to that diameter. Create a graph showing the sum. (Figure 3)
Therefore, the middle point (A) in FIG. 3 represents the total volume 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) in equilibrium with the curve on the X axis. The 75% volume diameter (D ₇₅ ) is the value at the point (D) intersecting the X axis by drawing a line from the point (C) in equilibrium on the Y axis.

(PVC Blackness) The PVC blackness is obtained by adding the carbon black of the present invention to a PVC resin, dispersing it with a two-roll and making it into a sheet, and using carbon black “# 40” and “# 45” of Mitsubishi Chemical Corporation. The blackness of each sample was set to 1 point and 10 points, and a reference value was determined, and the blackness of the sample was evaluated by visual judgment.

(T%) Toluene coloring power (T%) is AST
Determined according to MD-1618-83.

(Dispersion Index) The dispersion index was evaluated by the following method. The dispersed state 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. 250c
c Sample carbon black is mixed with LDPE resin in an amount of 40% by weight in a Banbury mixer and kneaded at 115 ° C. for 4 minutes. Blending conditions LDPE resin 101.89 g Calcium stearate 1.39 g Irganox 1010 0.87 g Sample carbon black 69.43 g

Next, at 120 ° C., it is diluted with a two-roll mill so that the carbon black concentration becomes 1% by weight. Conditions for preparing diluted compound LDPE resin 58.3 g Calcium stearate 0.2 g Carbon black 40% mixed resin 1.5 g Slit width is made into a sheet, this sheet is cut into chips, and 65 ± 3 μm on a 240 ° C. hot plate.
To form a film. The diameter distribution of undispersed aggregates having a diameter of 0.2 mm or more in a visual field of 3.6 mm × 4.7 mm is measured with an optical microscope with a magnification of 20 ×, and the total area thereof is calculated. This area is calculated by dividing the total area by the reference area based on the area of the undispersed agglomerate having a diameter of 0.35 mm as the number of reference particles. This is observed for 16 fields or more, and the average value is used as the dispersion index.

(Heat-resistant aging time) The heat-resistant aging time was evaluated by the following method. Dispersant (magnesium stearate)
Carbon black is mixed with 40% of the mixture and pulverized and mixed with a household mixer for 10 minutes to prepare a dry color. Next, dry color was mixed in polypropylene compound with 1.25% (carbon black 0.5%) in a bumper mixer at 140 ° C. for 20 minutes, and then 2
A sheet is formed at 170 ° C. with this roll mill. Mold temperature 22
Press molding is performed at 0 ° C. and a molding pressure of 100 kgf / cm ² to form a 2 mm thick flat plate. Each of the five test pieces created in this way is placed in a gear-type oven set at 150 ° C.
A heat aging test is carried out for 5 hours. The time when the surface began to turn white visually was taken as the heat aging time.

(Comparative Examples 1 to 3) Using the carbon black manufacturing furnace used in the examples, the combustion gas temperature at the raw material hydrocarbon introduction position, the reaction stop position, the amount of potassium added, and the choke gas flow rate in Table 1 were adjusted. Carbon blacks having the physical properties shown in Comparative Examples 1 and 2 were obtained. In addition, Comparative Example 3
Shows the physical properties of commercially available carbon black. Comparing each Example with Comparative Example 1, in comparison with Comparative Example 1, P
VC blackness is significantly high. This is considered to be because in Comparative Example 1, the particle size is out of the range specified by the present invention. Further, comparing each example with the comparative example 2, in the example, T%
The value of is high. This indicates that the proportion of unreacted polycyclic aromatic hydrocarbons in carbon black is low, which means that the safety of carbon black is high. The value of the ratio of Comparative Example 2, N ₂ SA / SEM is believed to be due to out of the range defined in the present invention, N ₂ SA /
It shows that there is a correlation between the SEM ratio and the ratio of unreacted polycyclic aromatic hydrocarbons. Comparing each Example with Comparative Example 3, the heat aging time in Comparative Example 3 is significantly shorter than that in Example. It is considered that this is because the pH is out of the range specified in the present invention.

[0057]

[Table 1]

[0058]

The carbon black of the present invention, when used as a black pigment in a resin colorant, a printing ink or a paint, satisfies the blackness and dispersibility which are conventionally difficult due to the trade-off relationship. Productivity can be improved. In addition, it has excellent effects of preventing deterioration when it is made into a resin composition, abrasion resistance when it is made into a rubber composition, and further, preventing aggregation when it is made into a coating composition. Therefore, it is very useful in the preparation of resin colorants, paints and rubber compositions.

[Brief description of drawings]

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

FIG. 2 is a diagram showing how to determine a maximum frequency Stokes equivalent diameter (D _mod ) and a Stokes equivalent diameter _half- value width (D _1/2 ).

FIG. 3 is a diagram showing how to determine a volume 75% diameter (D ₇₅ ).

[Explanation of symbols]

1st reaction zone 2 Second reaction zone 3rd reaction zone 4 Refractory furnace 5 Fuel and nozzle for introducing oxidant gas 6 Raw oil introduction nozzle 7 Reaction stop fluid introduction nozzle 8 control valves

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-9-235485 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09C 1/48 C08K 3/04 C08L 21 / 00 C09D 7/12 C09D 11/00

Claims (9)

(57) [Claims] 1. An average particle size of less than 13 nm and N ₂
Carbon black having a SA / SEM specific surface area ratio of more than 1.3 and a pH value of 5 or more. 2. The D _mod is 80 nm or less.
The listed carbon black. 3. The carbon black according to claim 1, wherein the ratio of D _1/2 / D _mod is 0.6 or less. 4. The carbon black according to claim 1, wherein the ratio of D _1/2 / D _mod is less than 0.55. 5. The carbon black according to claim 1, wherein cDBP is 50 cc / 100 g or more. 6. A coating composition containing the carbon black according to any one of claims 1 to 5. 7. A resin composition containing the carbon black according to any one of claims 1 to 5. 8. A rubber composition comprising the carbon black according to any one of claims 1 to 5. 9. An ink composition containing the carbon black according to any one of claims 1 to 5.