JP2000290531A - Carbon black processing apparatus, carbon black processing method, and method for producing oxidized carbon black - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient process and a device suitable for removing deleterious by-products from a carbon black which was oxidized using a nitrogen-containing oxidizing agent, and a compact, inexpensive device which allows no attachment of carbon blacks, etc. SOLUTION: In a device for treating carbon blacks which possesses a jacket wherein heat media are allowed to flow through and a mobile hollow body equipped with an agitating blade at the outside surface, carbon blacks are heated while being stirred. Preferably, the device possesses multiple mobile hollow bodies equipped with agitating blades at the outside surface, wherein the multiple hollow bodies are communicated via a hollow axis and stirs the carbon blacks by rotating around the axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing oxidized carbon black and an apparatus for treating carbon black. More particularly, the present invention relates to a processing method for removing harmful by-products from carbon black oxidized with a nitrogen-containing oxidizing agent, and a processing apparatus suitably used for such processing.

[0002]

2. Description of the Related Art It is known that carbon black is oxidized to impart an acidic functional group to the surface to improve dispersion in various vehicles, and ozone, nitric acid, nitric oxide and the like are known as oxidizing agents. ing. The functional groups and the properties of the surface introduced by the oxidation of carbon black have not yet been sufficiently elucidated, and there are differences in the expression of the physical properties of the oxidized carbon black obtained depending on each oxidizing agent and oxidizing conditions. Nitrogen-containing oxidizing agents such as nitric acid and nitric oxide are useful for obtaining oxidized carbon black having good physical properties. However, when these nitrogen-containing oxidizing agents are used, harmful oxidation by-products remain in the carbon black and need to be removed.

Conventionally, carbon black is oxidized by placing carbon black in a heating device such as a rotary drum type device or a fluidized bed type reactor, and introducing a gas flow and an oxidizing agent into the heating device. There has been known a method of removing oxidation by-products from the surface of carbon black by oxidizing and subsequently heating while introducing a gas such as air (Japanese Patent Publication No. 44-5691).

[0004]

However, such a conventional technique has the following problems. In such a method of removing harmful oxidation by-products by supplying air into a device such as a rotary drum device and contacting it with carbon black at a predetermined temperature, the air is introduced into the device in order to increase efficiency. If the flow velocity of the gas is increased, the carbon black powder is blown out of the rotary drum type device accompanying the gas flow, and it is difficult to adjust the residence time in the rotary drum device. In order to increase the amount of air introduced per unit time per unit weight of carbon black to increase the production amount, and to secure a predetermined residence time, it is necessary to increase the apparatus diameter and the apparatus length, There is a problem that equipment costs, maintenance costs, and the like are high.

In order to efficiently increase the temperature of the carbon black in the rotary drum device, it is necessary to increase the heat conduction area inside the rotary drum device. Is required. Also, it is difficult to control the temperature inside the device. In the method using a rotary drum device, a device having a heat transfer tube in the rotary drum is used, and carbon black is heated by heat transfer from the heat transfer tube. Then, it is necessary to increase the number of heat transfer tubes inside the rotating drum, so that the structure inside the rotating drum becomes complicated and fine irregularities are unavoidable. The problem arises.

When removing by-products from carbon black oxidized with a nitrogen-containing oxidizing agent, an exothermic reaction occurs, and the temperature of the carbon black increases. Since carbon black flows in the rotating drum in the axial direction, in order to adjust the temperature of the heated carbon black, it is necessary to reduce the amount of hot air introduced into the rotating drum, lower the temperature of hot air, or reduce the temperature of the body jacket. There is no other way but to lower it. According to these methods, when the carbon black is continuously introduced into the rotating drum, the temperature of the carbon black on the inlet side is lowered to the level of the carbon black that has just entered the rotating drum, and the efficiency becomes very poor. Driving is also difficult. In the case of batch operation, an additional service tank is required, which increases costs. It is also difficult to discharge products.

An object of the present invention is to provide an efficient method and a suitable apparatus for removing harmful by-products from carbon black oxidized by using a nitrogen-containing oxidizing agent. An object of the present invention is to provide a device free from adhesion or the like.

[0008]

Means for Solving the Problems The present inventors have made intensive studies in view of the above problems. As a result, they have found an apparatus and a method that are simple and inexpensive in structure and that can efficiently remove harmful by-products from oxidized carbon black. That is, the present invention provides (1) a carbon black processing apparatus having a jacket through which a heat medium can flow, and a movable hollow body having a stirring blade on the outer surface, and capable of heating while stirring carbon black. (2) It has a plurality of movable hollow bodies having stirring blades on the outer surface, and the plurality of hollow bodies are communicated by a hollow shaft, and the carbon black can be stirred by rotating around the shaft. The carbon black processing apparatus according to the above (1),

(3) The above-mentioned (1), wherein the movable hollow body having a stirring blade on the outer surface and the hollow portion of the hollow shaft communicate with each other and have a structure in which a heat medium flows.
Or the carbon black processing apparatus according to (2), (4)
The carbon black processing apparatus according to any one of the above (1) to (3), wherein the hollow body has a disk shape, (5) the above (1).
A method for treating carbon black, characterized in that the carbon black is heated in the carbon black treatment apparatus according to any one of (4) to (4), (6) carbon black is oxidized with nitric acid or nitrogen oxide, and 1) ~
(4) A method for producing oxidized carbon black characterized by removing the nitrogen compound attached to the carbon black by heating in the carbon black processing apparatus according to any one of (4) and (7). The heating in the carbon black processing apparatus according to any one of (4) to 100 to 1
(6) The method for producing oxidized carbon black according to the above (6), which is carried out at 80 ° C.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below.
The type of carbon black to be treated in the present invention is not particularly limited. The carbon black typically includes, but is not limited to, a furnace black obtained by a furnace method and a channel black obtained by a channel method. In particular, furnace black is relatively inexpensive and is generally distributed in large quantities, but carbon black produced in a production furnace often has an insufficient amount of acidic functional groups on the surface, and is not suitable for oxidation treatment. Often provided. The carbon black may be in the form of powder in the state of being recovered from a carbon black production furnace, in the form of granules obtained by dry granulation or wet granulation of the powder, or in the form of flakes obtained by a compression operation. Things and the like,
In the present invention, the carbon black can be used without any particular limitation. However, from the viewpoint of reaction efficiency, powdery carbon black is generally preferably used.

As the oxidizing agent used in the oxidation treatment, ozone, nitric acid and nitrogen oxide are typical. In particular, when oxidizing using a nitrogen oxide such as nitric acid or nitric oxide, various oxidizing agents are used as by-products. It is known that nitrogen-containing compounds remain in carbon black. Therefore, it is necessary to remove them.

In the present invention, the removal at this time is performed by treating the carbon black in a specific device. The treatment is to remove the adhered components by stirring, and furthermore,
Achieving effects obtained by stirring carbon black in the apparatus, such as efficient removal of adhering components by heating while stirring.

This apparatus has a jacket through which a heat medium can flow, and a movable hollow body having a stirring blade on the outer surface. It is desirable that a plurality of hollow bodies be provided. It is desirable that the plurality of hollow bodies be connected by a hollow shaft and rotate around the shaft. Further, it is preferable that the hollow portion of the hollow body and the hollow portion of the shaft communicate with each other, and a heat medium flows through these hollow portions. More specifically, it is preferable that a plurality of coaxial hollow bodies are provided in a jacketed casing at appropriate intervals as shown in an example of the apparatus of the present invention described below. is there. By taking such a configuration, the carbon black is a structure that is heated by heat conduction from a heat medium flowing through the hollow body and the jacket,
It is possible to adopt a structure in which the carbon black is stirred while being moved in the axial direction and can be heated.

An example of an apparatus that can be suitably used in the present invention will be described below with reference to FIGS. Reference numeral 1 denotes a casing, which has a shape along the shape of the lower part of the hollow body 11. The hollow body has a disk shape, and the lower part of the casing has an arc shape. A heat medium flows through the hollow portion inside the hollow body. The heat medium may be any medium that can be heated to a desired temperature, such as steam. It is desirable to adopt a structure in which a heat medium for transmitting heat to carbon black flows in the movable hollow body and the hollow portion in the shaft. Since the heat flow transfers heat to the carbon black by heat conduction from the surface of the stirring blade section, it is possible to heat the carbon black more efficiently than heat transfer by heat transfer of a high-temperature gas or the like. Therefore, in order to make the apparatus as compact as possible, it is desirable to design the surface area of the stirring blade section as wide as possible.

The term "movable hollow body" means that the hollow body is rotatable around an axis and the like, and indicates that the hollow body has a structure capable of stirring carbon black with a stirring blade provided. When the hollow body 11 rotates around the axis, the carbon black flows in the axial direction while being stirred by the stirring blade 28 provided in the hollow body. The angle of the stirring blade 28 with respect to the hollow body has a variable structure, and by changing this angle, the residence time of carbon black in the apparatus can be adjusted. The angle can be adjusted by loosening the bolt. The shape of the wing may be any shape as long as it can be efficiently stirred, and may be a general wing shape.

The material of the casing is preferably a metal having corrosion resistance such as stainless steel. Reference numeral 2 denotes an upper lid for separating the upper part of the casing 1 from the atmosphere. The upper lid has a main body and a flange structure, which are connected to each other via a sealant such as a gasket or an O-ring. Reference numeral 3 denotes a heating and cooling jacket for heating and cooling the outer peripheral portion of the casing 1 to maintain the carbon black powder at a predetermined temperature. Any material can be used as long as it can maintain a structure such as carbon steel or stainless steel. Reference numeral 4 denotes a space through which the heat medium flows, which has a three-part structure of 4a, 4b, and 4c. This has a structure in which the temperature of the heat medium can be changed so that the temperature of the carbon black is set to a desired temperature. Reference numeral 5 denotes a carbon black supply nozzle from which carbon black is introduced into the casing. 6 is a carbon black discharge nozzle, and 7 is a heating medium supply nozzle. The temperature of the heat medium can be adjusted with a pressure reducing valve or the like.

Reference numeral 12 denotes a supply nozzle for supplying a heat medium into the rotation shaft, and reference numeral 13 denotes a discharge nozzle for discharging the heat medium from the rotation shaft. Reference numeral 14 denotes a rotary joint for cutting off the rotary shaft 9 and the inlet-side fixed portion.
Is a rotary joint for cutting off the rotating shaft 9 and the outlet side fixed portion, 16 is a bearing of the inlet side rotating shaft 9, 17 is a bearing of the outlet side rotating shaft, and 18 is a ground packing of the inlet side. 19 is a gland press for tightening 19, 19 is a gland packing on the entrance side, 20 is a gland press for tightening the gland packing on the exit side, 21 is a gland packing on the exit side, and 19 is a gland portion. Similarly to the above, any structure may be used as long as the shaft seal has a structure that can seal the atmosphere and the internal atmosphere.

Reference numeral 22 denotes a heated air supply nozzle, and the air supplied from the nozzle is provided with water coming out of carbon black,
It becomes a carrier gas for discharging harmful by-products to the outside. Reference numeral 23 denotes an exhaust nozzle for discharging air supplied from the heated air supply nozzle 22. 24
Is a gear fixed to the outer peripheral portion of the rotating shaft 9, 25 is a chain for transmitting power from the electric motor, and 2 is a chain.
Reference numeral 6 denotes a motor-side gear, and 27 denotes a motor with a variable speed reducer, which can determine a predetermined rotation speed. Reference numeral 29 denotes an adjusting plate for adjusting the charged amount of carbon black in the apparatus.

At the same time, the casing also has a jacket structure so that carbon black can be heated to a desired temperature by heat conduction. The heat medium used here may be any heat medium as long as it can transfer heat to the carbon black, such as steam or heating oil. Since heat is generated when removing by-products such as nitrogen-containing compounds from the oxidized carbon black, it is necessary to remove heat in order to maintain the carbon black at a desired temperature. For this purpose, the jacket of the casing portion is divided, and the temperature of the heat medium can be controlled for each divided jacket. The cooling may be performed by partially flowing the refrigerant through the divided jacket. The refrigerant may be any medium, such as water or hot water, as long as it can lower the temperature of carbon black.

Reference numeral 8 denotes a cooling medium discharge nozzle in the jacket 4c. Reference numeral 9 denotes a rotating shaft having a hollow shaft structure, and reference numeral 10 denotes a flow path through which the heat medium flows in the rotating shaft. The temperature control of the carbon black in the apparatus is to maintain the desired temperature by providing a thermocouple insertion nozzle in the casing, detecting the carbon black temperature in the flow direction, and adjusting the heating and cooling medium temperature of the split jacket. Is possible.

Adjustment of the residence time of carbon black in the apparatus is performed by adjusting the supply amount from the carbon black supply nozzle 5
Adjustment is also possible by changing the height of the adjustment plate. The charged carbon black is discharged while being stirred in the flow direction at a repose angle.

In order to remove by-products adhering to carbon black, it is necessary to keep the carbon black powder under desired temperature conditions. This temperature is 100 to 100 in the case of removing nitrogen-containing compounds by-produced by oxidation with nitric acid or the like.
180 ° C. When the temperature is preferably 120 to 160 ° C, more preferably 130 to 150 ° C, by-products can be efficiently removed. As the processing apparatus of the present invention described above, a commercially available groove-type stirring dryer used for drying powder such as resin pellets, sugar, and starch can also be used.

[0023]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. (Example 1) "# 47" manufactured by Mitsubishi Chemical Corporation was oxidized by the following method. A mixed gas having a nitric acid gas concentration of 5.0% by volume obtained by evaporating 70% nitric acid in air is preheated to 100 ° C., and a gas flow of 10 m / sec is set at a gas temperature of 10%.
It is circulated in a pipe controlled at 0 ° C., and is dispersed by an ejector while quantitatively supplying carbon black at a rate of 240 g / min such that nitric acid is 15.0 parts by weight with respect to 100 parts by weight of carbon black. After the carbon black was oxidized with the residence time in the pipe being 20 seconds, the gas flow accompanying the carbon black was cooled to 50 ° C., and the gas after the reaction and the oxidized carbon black were separated in the collection bag. Obtained oxidized carbon black (NO ₂ amount
20,000 ppm) was introduced into a groove-type stirring dryer “thermoprocessor (25w-1.1 type)” manufactured by Hosokawa Micron Co., Ltd., as schematically shown in FIGS. 1 and 2, to remove oxidation by-products. The processing conditions are as follows. Number of rotations of the shaft 10: 30 rpm Temperature of carbon black: 120 to 160 ° C. Residence time of carbon black in the apparatus: 18 to 60 minutes Supply amount of carbon black: 16 kg / hr

For the above oxidized carbon black, the NO ₂ amount of the treated oxidized carbon black collected from the discharge nozzle 6 was measured. As shown in Table 1, it was confirmed that NO ₂ could be removed up to 30 PPM in 30 minutes. The NO ₂ was measured using a zinc-reduced naphthylethylenediamine method (NEDA method), which is JISk-0104 “A method for analyzing nitrogen compounds in exhaust gas”.

[0025]

[Table 1]

[0026]

According to the rotary kiln and the like conventionally used, a heating tube is arranged in a circumferential direction in the tube, and a reinforcing rib or the like for fixing the tube is required. Although the structure tends to cause the problem of
On the other hand, the device of the present invention has a simple internal structure, so that adhesion or the like hardly occurs inside the device. In addition, a large heat transfer area for transferring heat to the carbon black allows efficient heat treatment. In addition, in the conventional rotary kiln, since the effective charging amount is small, the apparatus itself becomes large and the manufacturing cost becomes high. On the other hand, the apparatus of the present invention has a large effective charging amount, so that the apparatus is compact and inexpensive. Unlike rotary kilns,
Since the outer jacket in the apparatus of the present invention is in a fixed state without rotating, the temperature of the internal carbon black can be easily controlled by adjusting the temperature of the heat medium in each of the divided portions in the axial direction.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an apparatus that can be suitably used in the present invention.

FIG. 2 is a diagram showing an example of an apparatus that can be suitably used in the present invention.

Claims (7)

[Claims] 1. A carbon black processing apparatus having a jacket through which a heat medium can flow, and a movable hollow body having stirring blades on its outer surface, and capable of heating carbon black while stirring it. 2. A plurality of movable hollow bodies having a stirring blade on an outer surface, wherein the plurality of hollow bodies are communicated by a hollow shaft,
The carbon black processing apparatus according to claim 1, wherein the carbon black can be stirred by rotating about the axis. 3. The structure according to claim 1, wherein a movable hollow body having a stirring blade on an outer surface thereof and a hollow portion of a hollow shaft communicate with each other so as to allow a heat medium to flow therethrough. Carbon black processing equipment. 4. The carbon black processing apparatus according to claim 1, wherein the hollow body has a disk shape. 5. A method for treating carbon black, comprising heating the carbon black in the apparatus for treating carbon black according to claim 1. Description: 6. A method of oxidizing carbon black with nitric acid or nitrogen oxides and heating the carbon black in the carbon black processing apparatus according to claim 1 to remove nitrogen compounds attached to carbon black. A method for producing oxidized carbon black. 7. The method for producing oxidized carbon black according to claim 6, wherein the heating in the apparatus for treating carbon black according to claim 1 is performed at 100 to 180 ° C.