JP2009138054A - Method for producing high purity carbon black - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple method for producing a high purity carbon black by efficiently removing metal components such as Fe and Cu contained in the carbon black as impurities. <P>SOLUTION: The method for producing high purity carbon black by removing metal from a carbon black aqueous dispersion includes a step of removing metal by bringing the carbon black aqueous dispersion into contact with a cation-exchange resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a simple method for obtaining purified carbon black by removing metal components such as Fe and Cu contained as impurities in carbon black.

Carbon black is widely used in the field of rubber applications centering on rubber reinforcements, applications such as resin colorants, printing inks and paints, and conductivity imparting agents for resins and the like.
The production method of carbon black is as follows: 1) Furnace method in which the raw material is incompletely burned, 2) Burning with a burner chip to form a flame, and the flame is brought into contact with channel steel and collected 3) Natural gas There are thermal methods for thermal decomposition. Of these, the furnace method is the most widely used. In the furnace method, mainly creosote oil and petroleum heavy oil are used as raw materials, and these are blown into the reaction furnace together with an amount of air that is less than the theoretical amount for complete combustion. Cool with water and finally capture with water to obtain an aqueous dispersion.
These carbon carbon black raw materials contain metal components such as Fe and Cu. Since these metal components are concentrated in the manufacturing process of carbon black, and there are also metal components from cooling water and manufacturing equipment, carbon black contains various metal components. For this reason, in applications where metal components are extremely hated, such as in the battery field and semiconductor field, it is required to remove those metal components as much as possible to achieve high purity.
As a method of reducing the metal amount of carbon black, an aqueous dispersion of carbon black was brought into contact with various water-soluble chelating agents to elute the metal components contained in the carbon black and capture them in the chelating agent so as to shift to the liquid phase. Thereafter, a method of solid-liquid separation (Patent Document 1), a method of separating an aqueous dispersion of carbon black by vigorous stirring and then filtering (Patent Document 2), a method of washing and eluting with an aqueous solution of an inorganic acid (Patent Document 3) There is.

JP 2005-113091 A Japanese Patent Laid-Open No. 2005-220320 JP 58-222157 A

  However, when a chelating agent or an inorganic acid is used to remove the metal from the carbon black, it is necessary to further remove the chelating agent or the inorganic acid from the purified carbon black. Thus, if the refined carbon black cannot be used as it is and a step for further removing the chelating agent or the like from the refined carbon black is required, the cost becomes higher, and the influence is particularly large on an industrial scale. Accordingly, an object of the present invention is to provide a simple method for producing purified carbon black by efficiently removing metal components such as Fe and Cu contained as impurities in carbon black.

As a result of intensive studies by the present inventors, it has been found that the object of the present invention can be achieved by bringing an aqueous dispersion of carbon black into contact with a cation exchange resin.
That is, the present invention is a method for producing purified carbon black by removing metal from an aqueous carbon black dispersion, wherein the metal black is removed by contacting the aqueous carbon black dispersion with a cation exchange resin. A method for producing purified carbon black containing

  According to the present invention, high purity carbon black can be easily obtained. The cation exchange resin used in the present invention is economically advantageous because it can be used repeatedly by regenerating.

〔Carbon black〕
Carbon black is generally an aggregate of fine spherical particles obtained by pyrolyzing, incomplete combustion, etc. of natural gas, acetyl, aromatic hydrocarbon oil, etc., and its production method includes furnace method, channel method, There are thermal methods.
In the present invention, various known carbon blacks can be used as the carbon black. For example, furnace black, channel black, lamp black and the like that are usually available can be used. Of these, it is more effective to use furnace black. Furnace black is made from petroleum-based, coal-based, and naphtha-based heavy oils that contain a large amount of metal components such as Fe and Cu. Furthermore, these metal components are concentrated in the manufacturing process and finally contained in carbon black. Therefore, the metal content is large, and the effects of the present invention are remarkably exhibited. As the carbon black, those in a state before being granulated, for example, those in an aqueous dispersion can be used.
As commercially available carbon black, for example, “# 3030B”, “# 3050B”, “# 3230B” manufactured by Mitsubishi Chemical Corporation, “Toka Black # 5500”, “Toka Black # 4500” manufactured by Tokai Carbon Co., “ Talker Black # 4400, Talker Black # 4300, Asahi Carbon Corporation “Asahi # HS-500”, “F-200”, “AX-010” “AX015”, Cabot Corporation “Vulcan XC-72”, Examples include “Ketjen Black EC300J” and “Ketjen Black EC600JD” manufactured by Ketjen Black International.

[Carbon black aqueous dispersion]
In the present invention, carbon black is brought into contact with a cation exchange resin as an aqueous dispersion. Therefore, in the present invention, when the carbon black is brought into contact with the cation exchange resin, the carbon black is in a dispersed state in water (hereinafter referred to as an aqueous dispersion medium) which may contain a water-soluble organic solvent. The dispersion state is preferably a state in which carbon black forms primary particles in the dispersion medium, but even if each particle is not in a completely dispersed state, that is, it forms secondary particles to some extent. It may be in the state. The particle size of carbon black is sufficiently small compared to the particle size of the cation exchange resin, and the carbon black can be present in the void formed by the particles of the cation exchange resin, and contact the surface of the cation exchange resin particle. I can do it.
As water used for preparing the aqueous dispersion, ion exchange water, ultrapure water, distilled water, and ultrafiltered water are preferably used in order to prevent impurities from being mixed.

Specific examples of the water-soluble organic solvent that may be contained in the aqueous dispersion medium include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, Alkyl alcohols such as isobutyl alcohol; ketones such as acetone and methyl ethyl ketone; dialkyl ethers such as ethylene glycol methyl (or ethyl) ether, diethylene glycol ethyl (or butyl) ether, diethylene glycol allyl ether, diethylene glycol diethyl ether, and triethylene glycol diethyl ether And esters such as methyl acetate, ethyl acetate, and butyl acetate can be used. Of these, alcohols are preferred which are less likely to volatilize and separate when mixed with water and can provide a stable aqueous carbon black dispersion. In particular, a lower alcohol having 1 to 4 carbon atoms is preferred. The amount of the water-soluble organic solvent added is preferably 10% by mass or less, and more preferably 5% by mass or less based on water.
The ratio of carbon black to the aqueous dispersion medium is preferably 1 to 30% by mass as a solid content. If the ratio of carbon black to water is less than 1% by mass, the throughput may increase and productivity may decrease. On the other hand, if it exceeds 30% by mass, the aqueous dispersion will become highly viscous and stirring will be difficult, resulting in reduced purification efficiency or when the cation exchange resin is used as a fixed bed continuous process. It can be difficult. In the present specification, the solid content of carbon black refers to the weight of carbon black powder obtained by drying carbon black collected by a membrane filter having a pore diameter of 1 μm at 150 ° C. for 24 hours.
The carbon black aqueous dispersion can be obtained by adding a predetermined amount of carbon black to the aqueous dispersion medium little by little and stirring. In addition, an aqueous dispersion of carbon black obtained in the process of cooling and collecting carbon black produced by incomplete combustion in the furnace method can be used as it is.

  It is desired that the stirring during the preparation of the aqueous dispersion is to dissolve carbon black to the primary particle size as much as possible. For this reason, it is preferable to mix the said aqueous dispersion liquid with a general disperser and a homogenizer. Specifically, disperser, high speed disperser, homogenizer, ultrasonic homogenizer, bead mill, colloid mill, jet mill, slasher mill, ball mill, sand mill, ultra fine mill, Eiger motor mill, dyno mill, pearl mill, agitator mill, cobol mill Mix with a 3-roll mill, 2-roll mill, or the like. These may be used alone or in combination. Among them, it is more preferable to use a stirring device such as a disperser or a homogenizer that can disperse a slurry having a relatively low viscosity and a large volume in a short time and can be continuously produced.

[Cation exchange resin]
As a cation exchange resin, a three-dimensional crosslinked polymer substrate obtained by polymerizing a monomer component (for example, styrene) and a crosslinkable monomer component (for example, divinylstyrene) is subjected to ion exchange such as a sulfonic acid group or a carboxyl group. Synthetic resins produced by introducing functional exchange groups can be used. Both strong acid type (sulfonic acid group) and weak acid type (carboxylic acid group, phosphoric acid group, etc.) can be used as exchange groups, but they have a large metal removal effect and have ion exchange properties in a wider pH range. The strongly acidic type is preferred.
Further, both sodium type (Na type) and acid type (H type) can be used depending on the counter ion, but the acid type is preferred from the viewpoint of a large metal removal effect and a reduction of the metal component as much as possible.
Furthermore, any of a simple gel type (gel type), an expanded network gel type (porous type), and a porous type (high porous type) obtained by adjusting the degree of crosslinking by increasing or decreasing the amount of the crosslinkable monomer during polymerization. Can also be used.
Specific examples of the cation exchange resin include strongly acidic cation exchange resins in the form of styrene sulfonic acid (for example, Rohm and Haas Japan, Amberlite IR120B, Amberlite 200CT, Mitsubishi Chemical “Diaion SK1B”). ”,“ Diaion RCP160M ”, etc.) or a weakly acidic cation exchange resin of acrylic acid or methacrylic acid carboxylic acid type, phosphoric acid type or hydroxyl group (for example, Amberlite IRC50,“ Diaion WK40 ”manufactured by Mitsubishi Chemical Corporation) , “Diaion WK10”, etc.). Among them, strong acid type strongly acidic cation exchange resins “SK1B”, “PK208”, “RCP160M” manufactured by Mitsubishi Chemical Corporation, “Amberlite IR120B”, “Amberlite 200CT” manufactured by Rohm and Haas, etc. can be preferably used. .
In the present invention, the used cation exchange resin can be regenerated and reused. Regeneration can be performed by washing with pure water and passing through a sodium chloride aqueous solution for Na type or a dilute hydrochloric acid aqueous solution for H type by a conventional method.

  In the present invention, in order to bring the carbon black aqueous dispersion into contact with the cation exchange resin, a method in which the cation exchange resin is added to the carbon black aqueous dispersion and, if necessary, fluidized by mechanical stirring, gas blowing or the like. Alternatively, it can be carried out by a method of circulating an aqueous carbon black dispersion in a packed bed filled with a cation exchange resin. In particular, a carbon black aqueous dispersion and a cation exchange resin are charged into a stirring tank and stirred (hereinafter referred to as “batch method”), and a carbon black aqueous dispersion is passed through a column filled with a cation exchange resin. The method (hereinafter referred to as “column method”) is advantageous because it can be carried out easily.

[Dispersant]
Prior to the step of bringing the cation exchange resin into contact with the aqueous carbon black dispersion, by adding a dispersing agent to the aqueous carbon black dispersion and stirring it, the metal removal rate by the cation exchange resin is significantly improved. Can be made.
As the dispersant used in the present invention, from the viewpoint that carbon black can be stably finely dispersed, a polymeric surfactant having a functional group having high affinity with carbon black, a water-soluble resin, and water dispersion Can be used. Examples of such surfactants include alkyl naphthalene sulfonic acid formalin condensates, acrylic copolymers, acrylic acid-styrene copolymers of styrene derivatives, styrene-maleic acid copolymers, polyvinyl alcohol, polyvinyl pyrrolidone, polyester series, Examples thereof include polyamide-based and polyurethane-based water-soluble resins and water-dispersible resins. Among these, alkyl naphthalenesulfonic acid formalin condensate, styrene-maleic acid copolymer, and polyvinylpyrrolidone are preferable.

In addition to the polymer surfactant, an anionic surfactant or a nonionic surfactant capable of improving the dispersibility of carbon black can be used.
Examples of the anionic surfactant include fatty acid salts, alkyl sulfate esters, alkylaryl sulfonates, alkylnaphthalene sulfonates, dialkyl sulfonates, dialkyl sulfosuccinates, alkyl diaryl ether disulfonates, and alkyl phosphates. Polyoxyethylene alkyl aryl ether sulfate, polyoxyethylene alkyl phosphate ester salt, glycerol borate fatty acid ester, polyoxyethylene glycerol fatty acid ester, and the like.
Nonionic surfactants include, for example, polyoxyethylene alkyl ethers, polyoxyethylene alkyl aryl ethers, polyoxyethylene derivatives, polyoxyethylene oxypropylene block copolymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene. Examples thereof include silicone surfactants such as sorbitol fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, acetylene diol, polyoxyethylene alkylamine, and polyoxyethylene alkylphenyl ether-modified silicone, and fluorine-based surfactants.

Examples of the cationic surfactant include aliphatic amine salts, quaternary ammonium salts, sulfonium salts, and phosphonium salts.
As the amphoteric surfactant, amino acid type compounds, betaine type compounds and the like can be used.
Among these, nonionic surfactants are preferable, and polyoxyethylene alkyl ethers and polyoxyethylene alkyl amines are more preferable.
The above surfactants and resins can be used alone or in combination.
Particularly suitable dispersants are naphthalene sulfonic acid formalin condensate, polyvinyl pyrrolidone, polyoxyethylene alkyl ether. Examples of the naphthalene sulfonic acid formalin condensate include Polyty N-100K (Lion Corporation), Demol N (Kao Corporation), and Cellflow (Daiichi Kogyo Seiyaku Co., Ltd.). -15 (Nippon Shokubai Co., Ltd.), Luvitec K (BASF), and polyoxyalkylene ethers such as EMALEX 100 series (Nippon Emulsion Co., Ltd.), Leocol SC-50 (Lion Corp.), etc. are available as commercial products And can be used.
The amount of the dispersant added is preferably 20 to 100% by mass as a solid content with respect to the carbon black contained in the carbon black aqueous dispersion. If it is 20% or less, the dispersion becomes insufficient, and the effect of adding the dispersant may not be sufficiently obtained, and when applied to the fixed bed method, it becomes difficult to circulate through the ion exchange resin packed tower. In some cases, the pressure loss increases due to clogging and the metal removal efficiency decreases due to drift. Further, if it is 100% or more, the metal removal efficiency may decrease due to the increase in foamability and viscosity, and when applied to the fixed bed method, the pressure loss may be caused to flow through an ion exchange resin packed tower. May become difficult due to the increase in

An aqueous dispersion with a reduced carbon black particle size can be obtained by adding a dispersant. By adjusting the amount of the dispersing agent and the like, a particle size of 20 μm or less, preferably 10 μm or less, more preferably 5 μm or less is obtained, so that it can be passed through an ion exchange resin packed column particularly when applied to the fixed bed method. Improved liquidity. The carbon black particle diameter can be measured using a dynamic light scattering method.
The viscosity at 25 ° C. of the aqueous carbon black dispersion is 1000 mPa · s or less, preferably 100 mPa · s or less, more preferably 20 ma · s or less, and can be adjusted by the amount of dispersant, the amount of carbon black added, and the like. In the above range, the liquid permeability of the column is improved. The viscosity can be measured using a B-type viscometer.

Examples of a method for separating purified carbon black from an aqueous carbon black dispersion include a method of centrifugation, a method of filtration, and a method of mixing an aqueous dispersion in a water-insoluble organic solvent. It is also possible to mix a flocculant with the aqueous dispersion to form a floc of carbon black and to filter. Examples of the water-insoluble organic solvent include toluene, xylene, benzene, chloroform, hexane, heptane and the like. Examples of the flocculant include synthetic polymer flocculants and inorganic flocculants, such as polyacrylamide, acrylamide / sodium acrylate copolymer, alkylamino methacrylate quaternary salt polymer, alkylamino acrylate quaternary salt / acrylamide copolymer. , Sulfuric acid band, polyaluminum chloride, etc. can be used alone or in combination. From the viewpoint of safety, a method of centrifugation or a method of filtration is preferred.
Carbon black has different types and amounts of impurities depending on the production method, but in any case, carbon black has a relatively large amount of heavy metal such as iron or copper, particularly iron, for example, furnace black. Ketjen black contains about 50 ppm. The purified carbon black obtained by the method of the present invention can reduce the amount of iron to about 2 to 10 ppm, depending on the content before removal.

An embodiment when the present invention is carried out by a batch method or a column method will be specifically described below.
[Batch method]
Preparation method of aqueous dispersion Prepare an aqueous dispersion obtained by stirring and mixing commercially available carbon black and water, or obtain it in the furnace method by cooling and collecting the carbon black generated by incomplete combustion with water. An aqueous dispersion of carbon black is prepared.
Purification method (1) Usually, 1 to 100% by mass of a cation exchange resin is mixed with the aqueous dispersion, and a general stirrer, for example, a homomixer, a paddle type, a turbine type or the like with a general stirring blade is attached. Stir for 1 to 200 hours in a stirring tank or the like. The amount of the cation exchange resin added is preferably 1 to 40% by mass and more preferably 1 to 20% by mass because it is easy to separate from the aqueous dispersion. When the amount of the ion exchange resin is large, when the ion exchange resin is separated, carbon black is accompanied with the ion exchange resin, which causes a decrease in the yield of carbon black.
(2) The obtained aqueous dispersion is separated into an ion exchange resin and an aqueous carbon black dispersion on a filter cloth or sieve having an opening of 0.045 to 0.075 mm. If the opening is larger than 0.075 mm, there is a high possibility that the ion exchange resin is mixed. If the opening is smaller than 0.045 mm, the separation efficiency is lowered due to the occurrence of clogging of carbon black.
(3) Separate carbon black from the aqueous dispersion.
(4) Purified carbon black can be obtained by heating and drying the carbon black separated by the above operation, but in conductive applications such as the battery field and semiconductor field, it can be heated and dried in an inert gas. preferable.

[Column method]
Aqueous dispersion preparation method Prepare as described for the batch method.
Purification method (1) A cation exchange resin is packed in a cylindrical column, etc., and an ion exchange resin packed tower is produced.
(2) The aqueous dispersion is preferably passed through the ion exchange resin packed tower at a space velocity (h-1) SV = 1 to 50, preferably 1 to 20, more preferably 1 to 10.
Here, SV is a space velocity, which is a value obtained by dividing the volume of the liquid volume capable of treating the aqueous dispersion in one hour by the volume of the ion exchange resin packed bed.
(3) The carbon black can be separated from the aqueous dispersion and thereafter by the same method as the batch method.

The carbon black, dispersant, cation exchange resin, pure water and hydrochloric acid used in Examples and Comparative Examples are shown below.
(1) Reagents used

(2) Analysis / evaluation method (i) Metal content measurement: high frequency inductively coupled plasma method First, a dilute hydrochloric acid aqueous solution (hereinafter, dilute hydrochloric acid A) prepared by mixing 10 ml of hydrochloric acid for atomic absorption analysis and 190 ml of pure water manufactured by Kanto Chemical Co., Ltd. A dilute hydrochloric acid aqueous solution (hereinafter, dilute hydrochloric acid B) prepared by mixing 20 mL of the hydrochloric acid and 180 mL of pure water was prepared. Subsequently, 200 mL of dilute hydrochloric acid A and 10 g of carbon black were added to a screw mouth bottle (500 mL), stirred for 1.5 hours at 150 rpm with a desktop shaker, and then separated into solid and liquid by vacuum filtration using a membrane filter (1 μm). I did it. The filtrate obtained by washing the carbon black remaining on the filter with 30 mL of pure water was transferred to a 500 mL beaker, heated at 300 ° C. for 1.5 hours and evaporated until the remaining amount was about 10 mL, and then 25 mL. The sample was transferred to a volumetric flask and diluted with dilute hydrochloric acid solution B and subjected to plasma atomic emission spectroscopy (ICP). As the ICP analyzer, Optima5300 DV (Perkin Elmer Japan Co., Ltd.) was used.
(Ii) Yield measurement {purified carbon black (g) / charged carbon black (g)} × 100
(Iii) Column liquid permeability A resin column was prepared by filling a glass chromatograph tube (inner diameter 30 mm, length 300 mm) with 170 mL of a strongly acidic cation exchanger (RCP160M). At the time of filling, the ion exchange resin was filled as a resin slurry to which an appropriate amount of pure water was added, and was always filled with pure water so that air did not enter the resin layer in the column. The entire amount of the carbon black dispersion was passed through this column to obtain a treatment liquid. After passing, the same amount of pure water as the carbon black dispersion was passed to wash the carbon black remaining on the column to obtain a cleaning solution. When the amount of carbon black recovered from the treatment liquid and the cleaning liquid obtained by the above operation is 95% by mass or more of the amount of carbon black contained in the carbon black dispersion before passing through the column, The property was set to “Good”.

(3) Examples <Batch type>
Examples 1-8
After adding 990 g of pure water to a 1 liter beaker (tank diameter: 230 mm), use a paddle type stirring blade (number of blades: 2, blade diameter: 32 mm, blade width: 12 mm, material: Teflon (registered trademark)) While stirring at a rotation speed of 200 rpm, 10 g of carbon black was added little by little, and 10% or 20% of a cation exchange resin was added at the stage where the total amount was added. This was stirred at room temperature for 3 hours, 6 hours or 168 hours at a rotation speed of 200 rpm, and then the resin was separated on a nylon filter cloth having an opening of 0.075 mm. Solid-liquid separation was performed by vacuum filtration using 5C filter paper. The wet carbon black remaining on the filter paper was dried at 150 ° C. for 24 hours to obtain a carbon black powder. The yield of the carbon black powder obtained and the amount of metal contained in the powder were measured. The results are shown in Table-3.

Comparative Examples 1-2
After adding 990 g of pure water to a 1 liter beaker (tank diameter: 230 mm), use a paddle type stirring blade (number of blades: 2, blade diameter: 32 mm, blade width: 12 mm, material: Teflon (registered trademark)) 10 g of carbon black was added little by little while stirring at a rotation speed of 200 rpm, and when the total amount was added, stirring was continued at a rotation speed of 200 rpm for 3 hours at room temperature, and then a nylon filter having an opening of 0.075 mm was used. The resin was separated on a cloth, and the resulting carbon black aqueous dispersion was designated as No. 1 Solid-liquid separation was performed by vacuum filtration using 5C filter paper. The wet carbon black remaining on the filter paper was dried at 150 ° C. for 24 hours to obtain a carbon black powder. The yield of the obtained carbon black powder and the amount of heavy metal contained in the powder were measured. The results are shown in Table-3.

<Batch type + dispersant addition>
Examples 9-16
After adding 990 g of pure water to a 1 liter beaker (tank diameter: 230 mm), use a paddle type stirring blade (number of blades: 2, blade diameter: 32 mm, blade width: 12 mm, material: Teflon (registered trademark)) Then, 10 g of carbon black was added little by little while stirring at a rotation speed of 200 rpm, and 200 g of the cation exchange resin and 10 g of the dispersant were added on top of the total amount added. Stirring was continued at room temperature for 3 hours at 200 rpm, and then the resin was separated on a nylon filter cloth having an opening of 0.075 mm. This was allowed to stand for 3 hours, and then solid-liquid separation was performed by vacuum filtration using a 1 μm membrane filter. The wet carbon black remaining on the filter was dried at 150 ° C. for 24 hours to obtain a carbon black powder. The yield of the obtained carbon black powder and the amount of heavy metal contained in the powder were measured. The results are shown in Table-4.
<Column type + dispersant>

Examples 17-20
After adding 990 g of pure water to a 1 liter beaker (tank diameter: 230 mm), use paddle type stirring blades (number of blades: 2, blade diameter: 32 mm, blade width: 12 mm, material: Teflon (registered trademark)) Then, 10 g of carbon black was added little by little while stirring at a rotation speed of 200 rpm, and after adding 10 g of the dispersing agent at the stage of adding the total amount, the mixture was stirred at a rotation speed of 200 rpm for 3 hours. This was passed twice through SV5.0 hr ⁻¹ through a column prepared by prepacking a glass chromatograph tube (inner diameter: 30 mm, length: 300 mm) filled with 170 mL of cation exchange resin. This was allowed to stand for 3 hours, and then solid-liquid separation was performed by vacuum filtration using a 1 μm membrane filter. The wet carbon black remaining on the filter was dried at 150 ° C. for 24 hours to obtain a carbon black powder. The yield of the obtained carbon black powder and the amount of heavy metal contained in the powder were measured. The results are shown in Table-5.

Comparative Examples 3-4
After adding 990 g of pure water to a 1 liter beaker (tank diameter: 230 mm), use a paddle type stirring blade (number of blades: 2, blade diameter: 32 mm, blade width: 12 mm, material: Teflon (registered trademark)) Then, 10 g of carbon black was added little by little while stirring at a rotation speed of 200 rpm, and stirring was continued at room temperature at the stage of adding the total amount, and then the solution was passed through the same column as in Examples 17-20. However, liquid passage was impossible due to clogging of the column.

Claims (3)

  A method for producing purified carbon black by removing metal from an aqueous carbon black dispersion, comprising the step of contacting the aqueous carbon black dispersion with a cation exchange resin to remove the metal. Production method.   2. The method for producing purified carbon black according to claim 1, comprising a step of adding a dispersing agent to the carbon black aqueous dispersion and stirring the step before contacting the aqueous carbon black dispersion with the cation exchange resin to remove the metal. .   The method for producing purified carbon black according to claim 1 or 2, wherein the dispersant is selected from the group consisting of a polymeric surfactant, a water-soluble resin, and a water-dispersible resin.