JP4747530B2 - Carbon black - Google Patents

Description

  The present invention relates to a carbon black suitable for blending into a conductive resin composition, and particularly to a carbon black suitable as an oil furnace carbon black produced by an oil furnace method.

  An apparatus for producing carbon black by an oil furnace method is installed following a first reaction zone for burning a fuel to produce a high-temperature combustion gas flow, and a carbon black raw material hydrocarbon (hereinafter referred to as oil). And a third reaction zone having a cooling means for stopping the carbon black production reaction, which is installed subsequently to the second reaction zone. And.

  In order to produce carbon black by this carbon black production apparatus, a high-temperature combustion gas flow is generated in the first reaction zone, and carbon black raw material hydrocarbon (oil) is sprayed in the second reaction zone. Carbon black is produced in the reaction zone. The gas stream containing carbon black is introduced into the third reaction zone, and is rapidly cooled by receiving water spray from the spray nozzle in the third reaction zone. The gas stream containing carbon black in the third reaction zone is then introduced into a collecting means such as a cyclone or a bag filter via a flue to collect the carbon black.

  In a conductive resin composition in which carbon black is blended with a resin composition, it is preferable to develop a carbon black structure in order to improve conductivity. In the carbon black having a developed structure, the carbon black primary particles are long and continuous in a branch shape or a kitchen shape, and the conductivity of the resin composition is improved. Moreover, the electroconductivity of a resin composition improves also by making the primary particle diameter of carbon black small. Furthermore, the conductivity is also improved by reducing the amount of functional groups (oxygen compounds) on the surface of the primary particles of carbon black.

Incidentally, the relationship between the production conditions of oil furnace carbon black, the particle size and the structure is described in paragraphs 0004 to 0008 of JP-A No. 2002-121422, and FIG. ₂ SA) and 24M4DBP absorption, the production limits of furnace black are disclosed.

  And as for the amount of hydrogen and the volume resistivity of carbon black itself, as shown in P552-555 of "Carbon Black Handbook" <Third Edition> (issued by the Carbon Black Association on April 15, 1995) and Fig. 1.7. Further, it is disclosed that the resistance of carbon black itself decreases when the hydrogen content decreases. Also, “Pigment” Vol. 39, No. 2, P36, FIG. 22 shows the hydrogen content and the volume of rubber (SBR system). A specific resistance relationship is disclosed.

JP Hei 8-507555, as a carbon black to be blended in the rubber composition of tire applications, CTAB adsorption specific surface area of 140~250m ² / g, CDBP absorption of 120~150cm ³ / 100g, nitrogen adsorption A carbon black having a specific surface area of 150 to 180 m ² / g, a Stokes mode diameter (D _mod ) of 40 to 67 nm, and a Stokes mode half-value width (D _1/2 ) of 47 nm or less is described. There is no description of the carbon black structure and the conductivity and fluidity of the conductive resin composition, not the carbon black for blending the conductive resin composition.

In the first place, not only the carbon black described in JP-T-8-507555, but also a carbon black for rubber compounding is used according to the present invention (1500 ° C. × 30 minutes) in order to ensure affinity with the matrix rubber. The carbon black having a large amount of dehydrogenation (1500 ° C. × 30 minutes) cannot obtain good conductivity.
JP 2002-121422 A JP-T 8-507555 "Carbon Black Handbook"<ThirdEdition> "Pigment" Vol. 39, No. 2

  Thus, in order to provide conductivity to the resin, a large amount of carbon black is mixed. However, the conventional resin composition in which carbon black is mixed as a conductive filler has insufficient conductivity, and its fluidity is low. For example, the resin composition does not flow to the corner of an injection mold. When used as a conductive coating material, there were problems such as failure to obtain a smooth coating film due to high viscosity when applied. Therefore, there has been a demand for a conductive filler (carbon black) that maintains high conductivity and improves the fluidity of the resin as compared with the prior art.

  An object of this invention is to provide the carbon black which can improve the electroconductivity and fluidity | liquidity of an electroconductive composition.

The carbon black of the present invention has the following characteristics.
24M4DBP ^absorption: 130 cm 3/100 g or more (1500 ° C. × 30 minutes) the dehydrogenation amount: 1.2 mg / g or less crystallite size Lc: 10~17Å
Preferably, in addition to the above, it further has the following characteristics.
-Nitrogen adsorption specific surface area is 150-300 m < ² > / g.
The ratio (D _mod / 24M4DBP) between the Stokes mode diameter (D _mod ) and the 24M4DBP absorption is 0.6 to 0.9.
-The average particle diameter by a transmission electron microscope is 14-24 nm.
-CTAB (cetyltrimethylammonium bromide) adsorption specific surface area is 120-220 m < ² > / g.
-DBP absorption is 150-400 cm < ³ > / 100g.
The oxygen-containing functional group density defined by the following formula is 3 μmol / m ² or less.
Oxygen-containing functional group density (μmol / m ² )
= [(1500 ° C. × 30 minutes) CO generation amount (μmol / g) + (1500 ° C. × 30
Min) CO ₂ generation (μmol / g)] / nitrogen adsorption specific surface area (m ² / g)

24M4 DBP absorption amount and DBP absorption amount in the present invention, (1500 ° C. × 30 minutes) dehydrogenation amount, crystallite size Lc, nitrogen adsorption specific surface area, Stokes mode diameter (D _mod ), and Stokes mode half width (D _1/2 ) The definitions of mean particle size, CTAB adsorption specific surface area, and oxygen-containing functional group density are as follows.

[24M4 DBP absorption and DBP absorption]
24M4DBP absorption and DBP absorption, conforms to JIS K6217 (unit ^cm 3 / 100g).

[(1500 ° C. × 30 minutes) Dehydrogenation amount]
(1500 ° C. × 30 minutes) The dehydrogenation amount (hereinafter simply referred to as “dehydrogenation amount”) is the amount of hydrogen in the gas generated during the heating of carbon black in vacuum at 1500 ° C. for 30 minutes. Specifically, it is measured as follows.
(Measurement method)
About 0.5g of carbon black is precisely weighed, put in an alumina tube, depressurized to 0.01 Torr (1.3 Pa), then the decompression system is closed, and it is kept in an electric furnace at 1500 ° C. for 30 minutes. Decomposes and volatilizes oxygen and hydrogen compounds. Volatile components are collected in a fixed-capacity gas collection tube through a quantitative suction pump. The amount of gas is determined from the pressure and temperature, the composition is analyzed by gas chromatography, the amount of hydrogen (H ₂ ) generated (mg) is determined, and the value converted to the amount of hydrogen per gram of carbon black is calculated (the unit is mg / g).

[Crystallite size Lc]
The measurement was performed using an X-ray diffractometer (RINT-1500 type, manufactured by Rigaku Corporation). The measurement conditions were such that Cu was used for the tube, tube voltage was 40 KV, and tube current was 250 mA. The carbon black sample was packed in a sample plate attached to the apparatus, the measurement angle (2θ) was 10 ° to 60 °, the measurement speed was 0.5 ° / min, and the peak position and half width were calculated by the software of the apparatus. Further, silicon for X-ray standard was used for calibration of the measurement angle. Using the results thus obtained, Scherrer's formula; (Lc (ｃ) = K × λ / β × cos θ (where K: form factor constant 0.9, λ: wavelength of characteristic X-ray CuKα). 5418 (Å), β: half width (radian), θ: peak position (degrees))).

[Nitrogen adsorption specific surface area]
The nitrogen adsorption specific surface area (N ₂ SA) is defined based on JIS K6217 (unit: m ² / g).
[Stokes mode diameter (D _mod ) and Stokes mode half width (D _1/2 )]
The Stokes mode diameter (D _mod ) and the Stokes mode half width (D _1/2 ) are obtained by the following measurement method.
(Measurement method)
Prepare a sample solution with a carbon black concentration of 0.01 wt% by adding precisely weighed carbon black to a 20 vol% ethanol aqueous solution containing 3 drops of a surfactant ("NONIDET P-40" manufactured by SIGMA CHEMICAL). did. This sample solution was subjected to a dispersion treatment for 20 minutes using an ultrasonic cleaning machine (ULTRASONIC STIRRING BATH: manufactured by LAKOMANUFACTURING CO.) To obtain a carbon black slurry. On the other hand, 10 ml of spin solution (pure water) is injected into a centrifugal sedimentation type flow rate distribution measuring device (“BI-DCP PARTICLSIZER” manufactured by BROOK HAVEN INSTRUMENTS), and further 1 ml of buffer solution (20% ethanol aqueous solution) is added. After the injection, 1 ml each of the prepared carbon black slurry was injected, centrifuged at 10000 rpm, and the Stokes equivalent diameter was calculated at a true specific gravity of 1.78 g / cm ³ , as shown in FIG. A histogram of the occurrence frequency relative to the diameter is made (however, in Comparative Examples 9 and 10 described later, the rotation speed is 4000 rpm and the true specific gravity is 1.84 g / cm ³ ). A straight line B is drawn parallel to the Y axis from the peak A of the histogram, and C is defined as the intersection with the X axis of the histogram. The Stokes diameter at C at this time is the Stokes mode diameter (D _mod ). Further, the midpoint of the straight line B is set as F, and the straight line G is drawn parallel to the X axis through F. The straight line G intersects the distribution curve of the histogram at two points D and E. At this time, the absolute value of the difference between the Stokes diameters at D and E is the Stokes mode half width (D _1/2 ).

[Average particle size]
It was determined by a transmission electron microscope. Specifically, a carbon black sample is dispersed in chloroform for 10 minutes using an ultrasonic disperser of 150 kHz and 0.4 kW to prepare a dispersed sample, which is sprinkled and fixed on a carbon-reinforced support film. This was photographed with a transmission electron microscope, and an enlarged image of 50000 to 200000 times was randomly measured using an Endter apparatus to measure the particle diameter of 1000 or more carbon blacks, and the average value was taken as the average particle diameter.

[CTAB adsorption specific surface area]
The CTAB adsorption specific surface area conforms to JIS K6217 (the unit is m ² / g).

[Oxygen-containing functional group density]
(1500 ° C. × 30 minutes) CO generation amount (hereinafter simply referred to as “CO generation amount”) and (1500 ° C. × 30 minutes) CO ₂ generation amount (hereinafter simply referred to as “CO ₂ generation amount”). Each of the carbon blacks is heated in a vacuum at 1500 ° C. for 30 minutes, and is the amount of CO and CO ₂ in the gas generated during this time. Specifically, it is measured as follows.
(Measurement method)
About 0.5g of carbon black is precisely weighed, put in an alumina tube, depressurized to 0.01 Torr (1.3 Pa), then the decompression system is closed, and it is kept in an electric furnace at 1500 ° C. for 30 minutes. Decomposes and volatilizes oxygen and hydrogen compounds. Volatile components are collected in a fixed-capacity gas collection tube through a quantitative suction pump. Together determine the amount of gas from the pressure and temperature, and composition analysis by gas chromatography, determined occurrence amount of carbon monoxide (CO) and carbon dioxide (CO ₂₎ to (mg), CO and CO ₂ from the carbon black 1g per The value converted into is calculated (unit: mg / g).
Further, the generated amount of each gas obtained is converted to μmol / g, and the oxygen-containing functional group density is determined by the following formula.
Oxygen-containing functional group density (μmol / m ² )
= [CO generation amount (μmol / g) + CO ₂ generation amount (μmol / g)]
/ Nitrogen adsorption specific surface area (m ² / g)

  According to the present invention, when blended in a resin composition, there is provided a carbon black that can simultaneously improve both its conductivity and fluidity.

  That is, according to the present invention, in the carbon black having a specific 24M4DBP absorption amount, the hydrogen content is decreased, the crystallite size is set to a specific small numerical range, and more preferably, the aggregate size of the secondary particles is set to an absolute value. By setting a specific relative level range with respect to the structure level rather than the value, both the conductivity and fluidity of the resin composition containing this are in a good balance, both are good without deterioration It was invented based on the novel knowledge of maintaining a unique property.

  As a result of intensive studies by the present inventors, carbon black, particularly carbon black by the oil furnace method, is graphitized in the vicinity of the surface of the primary particles, and the inside is made amorphous so that this can be used as a conductive filler. It has been found that when mixed with a resin composition, the resin composition can obtain good fluidity while maintaining high electrical conductivity. In order to achieve this, the inventors have found that the above-mentioned effects can be achieved by keeping the hydrogen amount of carbon black below a specific value and keeping the crystallite size obtained by X-ray diffraction in a specific range, thereby completing the present invention. did.

  In addition, when carbon black is produced by, for example, an oil furnace method, the carbon black produced in the production furnace is graphitized in the vicinity of the surface of the primary particles as described above, and the inside is made amorphous. It was possible to produce by maintaining a specific temperature and residence time that would keep.

  In the resin composition using the carbon black of the present invention, both conductivity and fluidity are in a good balance, and it is possible to maintain good properties without any deterioration. The reason for this is not clear, but it is considered that the carbon black of the present invention is caused by the crystal growth (graphitization) in the vicinity of the primary particle surface and the inside of the primary particle being amorphous.

  In other words, carbon black that has been graphitized to the inside does not exhibit conductivity in the direction of the graphite crystal plane (horizontal direction), and only exhibits conductivity in the vertical direction. The conductivity of the carbon black itself is reduced (because it is difficult for electricity to pass through the particles). However, the carbon black of the present invention is amorphous in the primary particles, so Since the conductivity of the carbon black itself is ensured by the inside of the primary particles (since electricity can pass through the carbon black primary particles), it is considered that sufficient conductivity can be maintained.

  In addition, the carbon black of the present invention is excellent in slipperiness with the resin because the surface in contact with the resin is graphitized, and it is considered that the fluidity of the resin composition does not decrease when it is in the resin composition. Further, the resin composition containing carbon black of the present invention has an amorphous inside of the carbon black primary particles, so that the carbon black is easily deformed in the resin, so that it is difficult to form an aggregate structure of the carbon blacks. Therefore, it is considered that the fluidity of the resin composition does not decrease.

The carbon black of the present invention is as follows:
24M4DBP ^absorption: 130 cm 3/100 g or more 1500 ° C. × 30 minutes dehydrogenation amount: 1.2 mg / g or less crystal size Lc: 10~17Å
It is.

The carbon black of the present invention further includes:
Nitrogen adsorption specific surface area: 150 to 300 m ² / g
D _{mod /} 24M4DBP: 0.6-0.9
Average particle size: 14-24 nm
CTAB adsorption specific surface area: 120-220 m ² / g
DBP absorption: 150-400cm < ³ > / 100g
Oxygen-containing functional group density: It is preferable to satisfy ³ μmol / m ² or less.

  In general, carbon black forms secondary particles composed of a chain called a unique structure in which primary particles are arranged in a kitchen shape. Since DBP (dibutyl phthalate) is absorbed in the voids of the kitchen chain, etc., the 24M4 DBP absorption amount and the DBP absorption amount are important index values of carbon black.

Carbon black of the present invention, 24M4DBP absorption of 130 cm ^3/100 g or more, preferably 140cm ^3/100 g or more, more preferably 145cm ^3/100 g or more. Is less than 24M4DBP absorption of 130 cm ^3/100 g, can not be obtained sufficient conductivity upon the resin composition. However, even if excessively high 24M4DBP absorption, and dispersibility deterioration in the resin, also increases the load of the furnace during production, since it is not economical, typically 260 cm ^3/100 g or less, preferably 200 cm ^3/100 g or less, particularly preferably 160cm ³ / 100g.

In addition, in the carbon black of the present invention, if the DBP absorption amount is too small, the conductivity may decrease when the resin composition is obtained, and conversely if too large, the fluidity of the resin composition may decrease. is there. Therefore DBP absorption 150 cm ^3/100 g or more and preferably is preferably 155cm at ^3/100 g or ^more, 400 cm 3/100 g or less, preferably 250 cm ^3/100 g or less, more 230 cm ^3/100 g or less, in particular 210 cm ^3/100 g or less It is preferable that

  In the present invention, the dehydrogenation amount of carbon black is 1.2 mg / g or less, preferably 1.0 mg / g or less, more preferably 0.8 mg / g or less, so that the resin composition containing this carbon black is blended. It becomes possible to increase the electrical conductivity of the object. In the present invention, the dehydrogenation amount is preferably 1.2 mg / g or less, but it is preferably as low as possible. In general, it is preferably 0.1 mg / g or more for reasons such as industrial economy.

  If the dehydrogenation amount is more than 1.2 mg / g, the crystal growth in the vicinity of the carbon black surface becomes insufficient, and it becomes easy to add an acidic functional group to the surface in the granulation drying process of the carbon black. In some cases, the electrical conductivity may decrease.

  In the present invention, the carbon black crystallite size Lc is 10 to 17 cm, preferably 11 to 16 cm. By setting it as this specific range, both the electroconductivity and fluidity | liquidity of a resin composition can be improved. If the crystallite size is too large, the conductivity may be lowered when the resin composition is obtained. Conversely, if the crystallite size is too small, sufficient conductivity may not be obtained.

In the present invention, the nitrogen adsorption specific surface area of carbon black is preferably 150 to 300 m ² / g. The greater the nitrogen adsorption specific surface area, the better the conductivity when the resin composition is made. However, if it exceeds 300 m ² / g, the resin composition has poor fluidity when it exceeds 300 m ² / g, for example, polyolefin, etc. Become. This is probably because carbon black adsorbs the plasticizer in the resin. In the present invention, by setting the nitrogen adsorption specific surface area to preferably 150 to 300 m ² / g, more preferably 200 to 290 m ² / g, both the conductivity and fluidity of the resin composition can be further improved. To do.

In the present invention, carbon black in which D _mod / 24M4DBP is in the range of 0.6 to 0.9 is further preferable. As described above, carbon black is composed of secondary particles (aggregates) in which a plurality of primary particles are connected, and 24M4DBP absorption is used as an indicator of the degree of development of the aggregate structure (structure). As another index for measuring the characteristics of carbon black, the Stokes diameter is known. The Stokes diameter is generally the diameter (mode diameter; D _mod ) determined by the centrifugal sedimentation method (DCP) on the assumption that the carbon black aggregate is a pseudosphere according to Stokes' law, and the D _mod As a distribution index, the half-value width (D _1/2 ) of D _mod is used.

Conventionally, using these indices, their ratio (D _1/2 / D _mod ), and other physical property values as physical index of carbon black, improvement of physical properties, workability, etc. in carbon black itself, rubber and resin composition Has been made. Conventionally, however, these numerical values are only evaluated individually, and the characteristics of carbon black have not been fully understood. For example, since only the Stokes mode diameter (D _mod ) of carbon black does not uniquely determine the development of the structure, there is a difference in conductivity even when the carbon black has the same D _mod. There has been a problem that the carbon black added to the composition has not been sufficiently improved.

Accordingly, the present inventors have studied _{intensively, D mod} is carbon black in a specific numerical range with respect to 24M4DBP absorption showing the development degree of structure, that is, the value of _D mod / 24M4DBP is in the specified range of carbon It has been found that by using black as a filler for a conductive resin composition, a conductive resin composition having an extremely excellent balance between conductivity and fluidity can be realized.

The numerical value indicated by D _mod / 24M4DBP indicates the size of the aggregate diameter with respect to the degree of carbon black structure development. The lower this value, that is, the higher the degree of development of the structure with respect to the aggregate size of the same size, the more dense the carbon black primary particles are. If this value is too low, the fluidity of the resin composition may decrease due to a decrease in familiarity with the resin, and the conductivity of the resin composition may decrease due to a decrease in the dispersibility of carbon black in the resin composition. Conversely, if it is too high, the conductivity of the carbon black itself will decrease, and the mechanical properties of the resin composition will decrease due to an increase in the amount of carbon black added to the conductive resin composition to give the desired conductivity. There is a case. Therefore, in the carbon black of the present invention, D _mod / 24M4DBP is preferably 0.6 or more and 0.9 or less.

Furthermore, the carbon black of the present invention preferably has a narrow aggregate diameter distribution with respect to the degree of structure development. Specifically, it is preferable that the numerical value indicated by the ratio (D _1/2 / 24M4DBP) of the Stokes mode half width (D _1/2 ) to the 24M4 DBP absorption amount is smaller. If this value is too high, the conductivity of the carbon black itself will decrease, and the mechanical properties of the resin composition will decrease due to the increase in the amount of carbon black added to the conductive resin composition to give the desired conductivity. There is a case. Therefore, D _1/2 / 24M4DBP in the carbon black of the present invention is preferably 0.9 or less. The lower limit is not particularly limited, but is preferably 0.45 or more for reasons such as production economics.

  The average particle size of the carbon black of the present invention is arbitrary, but it is preferably 14 to 24 nm, particularly preferably 15 to 18 nm. If this average particle size is too small, the dispersibility in the resin composition may be reduced. Conversely, if it is too large, the conductivity of the resin composition may be reduced.

Furthermore, in the present invention, the CTAB adsorption specific surface area of the carbon black is preferably 120 to 220 m ² / g, particularly 150 to ²⁰⁰ m ² / g. By setting it as this specific range, both the electrical conductivity and fluidity of the resin composition can be further enhanced. If the CTAB specific surface area is too small, the conductivity may be reduced, whereas if too large, the dispersibility in the resin composition may be reduced.

In addition to the above, in the present invention, the oxygen-containing functional group density defined by the following formula is preferably 3 μmol / m ² or less.
Oxygen-containing functional group density (μmol / m ² )
= [CO generation amount (μmol / g) + CO ₂ generation amount (μmol / g)]
/ Nitrogen adsorption specific surface area (m ² / g)

Here, this numerical value will be described. Carbon black has a certain amount of surface functional groups. When heated, carbon monoxide (CO) / carbon dioxide (CO ₂ ) is generated. For example, if a carbonyl group (ketone, quinone, etc.) is present, CO is mainly generated by decomposition, and if a carboxyl group and derivatives thereof (ester, lactone, etc.) are present, CO ₂ is similarly generated. That is, the amount of functional groups present on the surface of carbon black can be estimated by determining the amount of gas generated. On the other hand, it is conventionally known that a small amount of these functional groups is desirable for improving the conductivity of carbon black. However, numerical values based on the amount of gas generated per weight of carbon black have been conventionally used for these functional groups. In other words, it has been a conventional wisdom that the amount of functional groups relative to the weight of carbon black affects the conductivity.

  On the other hand, as a result of further intensive studies, the present inventors have determined that the amount of these functional groups is not a numerical value per unit weight of carbon black, but rather a unit per unit surface area. Has been found to be effective in achieving both the electrical conductivity of the resin composition, and thus the electrical conductivity and fluidity.

  Although the details of the reason are not clear, when an electric current flows through the resin composition, the functional group localized on the surface of the carbon black inhibits the electron transfer between the carbon black secondary particles. It is considered that the number per unit surface area (concentration) affects the conductivity rather than the amount.

That is, since the oxygen-containing functional group density indicates the number of functional groups per unit surface area of carbon black, this value is preferably low. When this numerical value is high, the conductivity of the resin composition containing carbon black decreases due to such a reason. Note that the lower the value, the better from the viewpoint of conductivity. However, if the value is too low, as described above, the dispersibility may be lowered and the conductivity and fluidity may be deteriorated. It is disadvantageous for reasons such as industrial economy. Therefore, the oxygen-containing functional group density is preferably 0.1 μmol / m ² or more.

  The method for producing carbon black of the present invention is arbitrary, and examples thereof include ketjen black by an oil furnace method, an acetylene method, and an activation method. Among these, the oil furnace method is preferable because it can be manufactured at low cost and with high yield.

  The oil furnace method will be described below as an example of the method for producing carbon black of the present invention.

  An example of an apparatus for producing carbon black of the present invention is shown in FIG. This apparatus is a carbon black production apparatus by an oil furnace method, and includes a first reaction zone A that burns fuel to generate a high-temperature combustion gas flow, and an introduction nozzle that is connected downstream and introduces a carbon black raw material. A second reaction zone B provided downstream thereof, and a third reaction zone C provided with a nozzle connected downstream thereof to supply cooling water or the like into the furnace in order to stop the carbon black production reaction.

  First, fuel is introduced in a spray form from the fuel introduction nozzle F, and this is mixed with combustion air from the combustion air introduction nozzle G and burned to obtain a high-temperature combustion gas flow. The temperature of the combustion gas stream is about 1300 ° C to 2000 ° C. The fuel used for generating the high-temperature combustion gas is arbitrary, but examples thereof include liquid fuels such as heavy oil, light oil, gasoline, and kerosene, and gaseous fuels such as natural gas, propane, and hydrogen. The generated high-temperature combustion gas flow passes through the production furnace having a gradually converged shape, thereby increasing the gas flow velocity and improving the turbulent energy in the furnace.

  Examples of the carbon black raw material introduced in the second reaction zone B include coal-based hydrocarbons such as creosote oil and petroleum-based hydrocarbons such as ethylene bottom oil. The particle diameter (primary particle diameter) and structure of carbon black can be adjusted by adjusting the introduction position and amount of the carbon black raw material.

  The carbon black produced in the second reaction zone B is brought into contact with cooling water or the like in the third reaction zone C and rapidly cooled to stop the carbon black production reaction. Thereafter, the gas and carbon black are generally separated by a collection device such as a bag filter or a cyclone to obtain carbon black. The obtained carbon black is generally subjected to a step of using water or the like as a granulating medium, granulating it to about 1 mm with a pin type wet granulator or the like, and then drying with a rotary dryer. .

Carbon black of the present invention, i.e., 24M4DBP oil absorption of 130 cm ^3/100 g or more, the dehydrogenation amount and not more than 1.2 mg / g, for crystallite size Lc of producing carbon black which is 10~17Å is By adjusting the position of the carbon black raw material introduction nozzle D ′ in the second zone B and the position of the cooling water supply nozzle E ′ in the third reaction zone C, the residence time of the carbon black in the furnace is set to a specific range. As described above, the carbon black 24M4DBP absorption amount and specific surface area are set to values within a specific range, Lc is set to a specific small value without being excessively large, and dehydrogenation of the carbon black particle surface is advanced. That's fine. Specifically, the furnace temperature is set to 1500 ° C. to 2000 ° C., preferably 1600 ° C. to 1800 ° C., and the residence time of carbon black in the furnace, that is, the time required to move from the raw material introduction point to the reaction stop position (in FIG. The time required to move the carbon black raw material introduction position distance D and the reaction stop position distance E) is 40 milliseconds to 500 milliseconds, preferably 50 milliseconds to 200 milliseconds. Further, in the case where the temperature in the furnace is lower than 1500 ° C., the residence time in the furnace exceeds 500 milliseconds and is 5 seconds or less, preferably 1 to 3 seconds.

  Since the carbon black of the present invention has a particularly small amount of dehydrogenation, a method of setting the temperature of the high-temperature combustion gas flow in the furnace to a high temperature of 1700 ° C. or higher, or further in the furnace downstream of the carbon black raw material supply nozzle. It is preferable to introduce oxygen to burn hydrogen etc. on the surface of the carbon black and lengthen the residence time at high temperature with this reaction heat. Such a method is preferable because crystallization near the surface of carbon black and dehydrogenation inside carbon black can be effectively performed.

  The carbon black of the present invention can be blended with a resin to obtain a conductive resin composition. Any resin can be used. Specifically, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, polybutene-1, propylene-ethylene block or random copolymer, ethylene-vinyl acetate copolymer, ethylene- Α-olefin resins such as acrylic acid copolymers, ethylene-methacrylic acid copolymers, maleic anhydride-modified polypropylene, maleic anhydride-modified polyethylene, and α-olefin polymers modified with vinyl monomers such as styrene and vinyl acetate. Polyamide resins such as nylon 6 and nylon 66; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyether resins such as polyacetal and polyphenylene oxide; polycarbonate resins; Styrenic resins such as rilonitrile-butadiene-styrene terpolymer (ABS) and high impact polystyrene; halogen-containing resins such as polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene; polymethyl methacrylate, polyacrylonitrile, etc. Examples thereof include acrylic resins and the like; polysulfone resins; thermoplastic resins such as polyphenylene sulfide resins and thermosetting resins such as phenol, melamine, and epoxy. Further, for the purpose of balancing the physical properties of the resin composition, these resins may be further mixed with rubber.

  Among these resins, olefin resins, polyacetal resins, polyamide resins, polyester resins, polyphenylene oxide resins, styrene resins and the like are preferable, particularly ethylene resins, polypropylene resins, propylene-ethylene block or random copolymer resins, polyamide resins, Styrenic resins are preferred.

  The amount of carbon black in the resin composition may be appropriately selected depending on the application. For example, in the case of an antistatic application, it is usually in the range of 1 to 30% by weight, preferably 2 to 15% by weight.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further in detail, this invention is not limited to a following example, unless the summary is exceeded. In addition, the preparation method of the resin composition in the following Examples etc. and its test method are as follows. Polyethylene and high impact polystyrene were used as the resin species.

<Formulation of polyethylene resin composition>
The composition of the polyethylene resin composition containing carbon black is as follows. The blending amount of carbon black is as shown in Tables 3 and 4.
Thermal stabilizer: Irganox 1010 (Nippon Ciba-Geigy Co., Ltd.) 0.5% by weight
Lubricant: Calcium stearate (manufactured by Sakai Chemical Industry Co., Ltd.) 0.8% by weight
Resin: Polyethylene (LF440HA: manufactured by Mitsubishi Chemical Corporation)

<Evaluation of conductivity of polyethylene resin composition>
Using a lab plast mill type C (manufactured by Toyo Seiki Seisakusho Co., Ltd.) with a Banbury mixer B250, the resin alone was first pre-kneaded for 2 minutes under the conditions of a kneading temperature of 115 ° C. and a rotational speed of 70 rpm. Other additives were added and kneaded for 7 minutes to prepare a resin composition. After making this resin composition into a sheet of about 1 mm thickness with a 6-inch mixing roll machine 191-TM type (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), this sheet is cut and heated and cooled test press machine (manufactured by Nisshin Kagaku Co., Ltd.). ) (Press temperature: 150 ° C., press pressure: 100 kg / cm ² , press time: 2 minutes) to produce a 10 cm × 10 cm × 0.2 cm flat plate for evaluation test. And the center part of this flat plate was cut out to width 2cm, and volume specific resistance value (VR) was measured according to the SRIS method (Japan Rubber Association method). For the measurement of the resistance value, a digital multimeter TR6847 (manufactured by Advantest) was used. A resistance value of 200 MΩ (about 1.3 × 10 7 Ω · cm in terms of VR) or more was measured with a high resistance meter 4329A (manufactured by YHP). It was judged that the smaller the VR, the better the conductivity.

<Evaluation of fluidity of polyethylene resin composition>
Based on JISK7210, the melt flow rate (MFR) of the resin composition was measured at a temperature of 190 ° C. and a load of 10 kgf.

<Composition of high impact polystyrene resin composition>
The composition of the high impact polystyrene resin composition containing carbon black is as follows. The blending amount of carbon black is as shown in Table 6.
Thermal stabilizer: Irganox 1010 (Nippon Ciba-Geigy Co., Ltd.) 0.5% by weight
Lubricant: Calcium stearate (manufactured by Sakai Chemical Industry Co., Ltd.) 0.5% by weight
Resin: High impact polystyrene (H8601: PS Japan Co., Ltd.) remaining

<Evaluation of conductivity of high impact polystyrene resin composition>
Using a lab plast mill C type (manufactured by Toyo Seiki Seisakusho Co., Ltd.) with a Banbury mixer B250, the resin alone was first pre-kneaded for 2 minutes under conditions of a kneading temperature of 135 ° C. and a rotation speed of 50 rpm, and then carbon black and Other additives were added and kneaded for 8 minutes to prepare a resin composition. After making this resin composition into a sheet of about 1 mm thickness with a 6-inch mixing roll machine 191-TM type (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), this sheet is cut and heated and cooled test press machine (manufactured by Nisshin Kagaku Co., Ltd.). ) (Press temperature: 160 ° C., press pressure: 100 kg / cm ² , press time: 2 minutes) to prepare a 10 cm × 10 cm × 0.2 cm flat plate for evaluation test. The electrical conductivity was evaluated by volume resistivity (VR) according to the same SRIS method (Japan Rubber Association method) as the polyethylene resin composition.

<Evaluation of fluidity of high impact polystyrene resin composition>
Based on JISK7210, the melt flow rate (MFR) of the resin composition was measured at a temperature of 200 ° C. and a load of 10 kgf.

Examples 1-4, Comparative Examples 1, 2, 4, 5
<Manufacture of carbon black>
Carbon black was produced using the carbon black production apparatus shown in FIG. 1 under the production conditions shown in Table 1 and in-furnace apparatus conditions such as the feedstock introduction position distance D and reaction stop position distance E. In addition, either of the following 2 types was employ | adopted for the furnace internal-diameter dimension D1-D3 and L1 in FIG.
A type: D1 = 1100 mmΦ, D2 = 175 mmΦ, D3 = 400 mmΦ,
L1 = 3300mm, D2 ′ = 190mmΦ
B type: D1 = 500 mmΦ, D2 = 55 mmΦ, D3 = 200 mmΦ,
L1 = 3200mm (D2 ′ = D2)
C type: D1 = 1100 mmΦ, D2 = 175 mmΦ, D3 = 400 mmΦ,
L1 = 2750mm (D2 '= D2)

  As fuel for the high-temperature combustion gas flow, heavy oil was used in Examples 1 to 4 and Comparative Examples 4 and 5, and LNG was used in Comparative Examples 1 and 2. In both the examples and comparative examples, the carbon black raw material (raw material oil) was creosote oil, and the furnace temperature in the second reaction zone was 1750 ° C. Table 1 shows the physical properties of the obtained carbon black.

Comparative Example 3
The carbon black obtained in Example 1 was filled in a graphite crucible having a volume of 70 liters, filled in an Atchison furnace, and the entire crucible was covered with a carbon black packing powder and energized.

  The temperature was raised to 2000 ° C. at a temperature raising speed of 35 ° C./min, and held at 2000 ° C. for 1 hour. After releasing the heat to room temperature, the carbon black was taken out. The characteristics of the obtained carbon black are shown in Table 1.

Comparative Examples 6-11
Table 2 shows the characteristics of commercially available conductive carbon black used as a comparison.

  Tables 3 and 4 show the evaluation results of the properties (conductivity and fluidity) of the polyethylene resin composition using the carbon black described above. For the polyethylene resin composition using carbon black described above, the fluidity (MFR [g / 10 min]) with the same conductivity (VR [Ω · cm]) was interpolated using the results shown in Tables 3 and 4. (However, the values in parentheses are extrapolated.) The results are shown in Table 5 and FIG.

  Table 6 shows the evaluation results of the characteristics (conductivity, fluidity) of the high impact polystyrene resin compositions using the carbon blacks of Examples 3 and 4 and Comparative Examples 6, 8, and 11. For the high impact polystyrene resin composition using carbon black described above, the fluidity (MFR [g / 10 min]) with the same conductivity (VR [Ω · cm]) was interpolated using the results in Table 6. The results are shown in Table 7 and FIG.

As apparent from Table 1, the carbon blacks of the present invention obtained in Examples 1 to 4, 24M4DBP absorption of 130 cm ^3/100 g or more, the dehydrogenation amount is 1.2 mg / g or less, and crystallite size Lc of 10 It has a characteristic of ˜17 cm. And as is clear from Tables 3 and 4, the polyethylene resin composition (resin composition Nos. 1-1 to 4-4) using the carbon black of the present invention and the polyethylene resin composition using the carbon black of the comparative example ( When the resin composition No. Co1-1 to Co10-4) is compared, the resin composition No. 1-1 to 4-4 are resin composition Nos. Compared to Co1-1 to Co10-4, the resin composition is excellent in electrical conductivity and sufficiently high in fluidity, and has a good balance between electrical conductivity and fluidity. I understand that.

  Further, as apparent from Table 5, a polyethylene resin composition (resin composition Nos. 1-1 to 4-4) using the carbon black of the present invention and a polyethylene resin composition (resin) using the carbon black of the comparative example. Comparing the composition Nos. Co1-1 to Co10-4), it can be seen that the resin composition using the carbon black of the present invention has a high MFR value and excellent fluidity when the conductivity is the same. . As is apparent from FIG. 3 in which the result is graphed, the resin composition using the carbon black of the present invention has both conductivity and fluidity compared to the resin composition using the carbon black of the comparative example. Are better.

  The carbon black of Comparative Example 11 is known as a highly conductive carbon black in Ketjen EC having a special structure of a high specific surface area, a high DBP, and a hollow shell. As can be seen from Tables 3, 4, 5 and FIG. 3, the polyethylene resin composition using the carbon black of Examples 1 to 4 of the present invention is equivalent to the polyethylene resin composition using the carbon black of Comparative Example 11. It exhibits electrical conductivity and fluidity higher than that.

  Further, as apparent from Table 6, the high impact polystyrene resin composition (resin composition Nos. 5-1 to 6-4) using the carbon black of the present invention and the high impact polystyrene resin using the carbon black of the comparative example. When the composition (resin composition No. Co12-1 to Co14-4) is compared, the resin composition No. 5-1 to 6-4 are resin composition Nos. Compared to Co12-1 to Co14-4, the resin composition is excellent in electrical conductivity and sufficiently high in fluidity, and has a good balance between electrical conductivity and fluidity. I understand that.

Further, as apparent from Table 7, the high impact polystyrene resin composition (resin composition Nos. 5-1 to 6-4) using the carbon black of the present invention and the high impact polystyrene resin using the carbon black of the comparative example. When the composition (resin composition Nos. Co12-1 to Co14-4) is compared, the resin composition using the carbon black of the present invention has a high MFR value when the conductivity is the same, and is excellent in fluidity. I know that. As is apparent from FIG. 4 in which the results are graphed, the resin composition using the carbon black of the present invention has both conductivity and fluidity compared to the resin composition using the carbon black of the comparative example. Are better. In particular, the carbon black of Comparative Example 11 which was comparatively good in the polyethylene type was significantly inferior in the balance between conductivity and fluidity in the high impact polystyrene type, whereas the carbon black of the present invention was not used. The conductivity and fluidity were good. Such conductivity and the stability of the fluidity, the carbon black of the present invention, 24M4DBP absorption of 130 cm ^3/100 g or more, the dehydrogenation amount is 1.2 mg / g or less, and crystallite size Lc is 10~17Å Because it has characteristics.

It is a schematic block diagram of a carbon black manufacturing apparatus. It is explanatory graph of a Stokes mode diameter ( _Dmod ) and a Stokes mode half value width (D1 _{/ 2} ). It is a graph which shows the result of the Example and comparative example in a polyethylene resin composition. It is a graph which shows the result of the Example and comparative example in a high impact polystyrene resin composition.

Explanation of symbols

A 1st reaction zone B 2nd reaction zone C 3rd reaction zone D Carbon black raw material introduction position distance D 'Carbon black raw material introduction nozzle E Reaction stop position distance E' Cooling water supply nozzle F Fuel introduction nozzle G Combustion air introduction nozzle

Claims (8)

Carbon black characterized by having the following characteristics:
24M4DBP ^absorption: 130cm 3 / 100g or more
Defined below and measured by the following measurement method (1500 ° C. × 30 minutes) Dehydrogenation amount: 1.2 mg / g or less
(1500 ° C. × 30 minutes) Dehydrogenation amount: This is the amount of hydrogen per gram of carbon black in the gas generated during heating for 30 minutes at 1500 ° C. in a vacuum, measured as follows. .
(Measurement method)
About 0.5g of carbon black is precisely weighed, put in an alumina tube, depressurized to 0.01 Torr (1.3 Pa), then the decompression system is closed, and it is kept in an electric furnace at 1500 ° C. for 30 minutes. Decomposes and volatilizes oxygen and hydrogen compounds. Volatile components are collected in a fixed-capacity gas collection tube through a quantitative suction pump. The amount of gas is determined from the pressure and temperature, the composition is analyzed by gas chromatography, the amount of hydrogen (H ₂ ) generated (mg) is determined, and the value converted to the amount of hydrogen per gram of carbon black is calculated (the unit is mg / g).
Crystal size Lc: 10-17Å The carbon black according to claim 1, wherein the nitrogen adsorption specific surface area is 150 to 300 m ² / g. 3. The carbon black according to claim 1, wherein a ratio (D _mod / 24M4DBP) of Stokes mode diameter (D _mod ) to 24M4DBP absorption is 0.6 to 0.9.   The carbon black according to any one of claims 1 to 3, wherein an average particle diameter measured by a transmission electron microscope is 14 to 24 nm. 5. The carbon black according to claim 1, wherein a CTAB (cetyltrimethylammonium bromide) adsorption specific surface area is 120 to 220 m < ² > / g. In any one of claims 1 to 5, carbon black, wherein the DBP absorption amount is 150~400cm ³ / 100g. 7. The carbon black as defined in claim 1, wherein the oxygen-containing functional group density is 3 μmol / m ² or less as defined below and measured by the following measurement method .
Density of oxygen-containing functional groups: The amount of carbon monoxide and carbon dioxide generated in the gas generated during heating for 30 minutes at 1500 ° C. in a vacuum is the amount per unit surface area of the carbon black. Is measured in this way.
(Measurement method)
About 0.5g of carbon black is precisely weighed, put in an alumina tube, depressurized to 0.01 Torr (1.3 Pa), then the decompression system is closed, and it is kept in an electric furnace at 1500 ° C. for 30 minutes. Decomposes and volatilizes oxygen and hydrogen compounds. Volatile components are collected in a fixed-capacity gas collection tube through a quantitative suction pump. Together determine the amount of gas from the pressure and temperature, and composition analysis by gas chromatography, determined occurrence amount of carbon monoxide (CO) and carbon dioxide (CO ₂₎ to (mg), CO and CO ₂ from the carbon black 1g per The value converted into is calculated (unit: mg / g). Further, the generated amount of each gas obtained is converted to μmol / g, and the oxygen-containing functional group density is obtained from the following formula.
Oxygen-containing functional group density (μmol / m ² )
= [(1500 ° C. × 30 minutes) CO generation amount (μmol / g) + (1500 ° C. × 30 minutes) CO ₂ generation amount (μmol / g)] / Nitrogen adsorption specific surface area (m ² / g)   The carbon black according to any one of claims 1 to 7, wherein the carbon black is oil furnace carbon black.

Images