KR20170051723A - Method for modifying surface of carbon black - Google Patents

Abstract

The present invention relates to a method for modifying the surface of carbon black, and more specifically, to a method for modifying the surface of carbon black which improves the introduction amount of sulfur-containing functional groups by preprocessing the surface of the carbon black. The method for modifying the surface of carbon black comprises the following steps: (a) preprocessing carbon black in a fine powder form under the atmosphere of oxidative gas; (b) mixing the preprocessed carbon black with water to obtain a mixture; (c) pulverizing the carbon black inside the mixture; and (d) supplying mixed gas containing sulfur compounds in a gas phase, and heat-treating the pulverized carbon black to obtain carbon black where sulfur-containing functional groups are introduced on the surface.

Description

METHOD FOR MODIFYING SURFACE OF CARBON BLACK [0002]

The present invention relates to a method for surface modification of carbon black, and more particularly to a method for surface modification of carbon black which improves the introduction amount of sulfur-containing functional groups through pretreatment of the surface of carbon black.

Carbon black is widely used in various fields as fillers and reinforcing pigments in compounding and preparing rubber compositions and plastic compositions as pigments such as ink compositions, paints and the like.

When carbon black is used as a pigment such as an ink composition or a paint, it is required to have excellent properties such as blackness, gloss, tinting strength, dispersibility and the like. On the other hand, when used as a reinforcing agent for a tire, it is excellent in abrasion resistance and low in hysteresis- .

Particularly, in relation to the rubber composition for producing tires, the elasticity of the rubber is due to the energy absorption ability of the crosslinked rubber skeleton. When the crosslinking density of the rubber is high, the tensile strength is high and the elongation is low. The crosslinking density should be carefully controlled.

On the other hand, a reinforcing agent such as carbon black is added to the rubber so as not to increase the modulus (MODULUS) while increasing the tensile strength since there is a limit to increase the crosslinking density.

The characteristics of the filler directly affecting the reinforcing effect of the rubber include the size of the carbon black particles, the surface area and the structure of the particles, but all of these properties are related to the physical bonding between the carbon black and the rubber.

That is, in the composition in which the carbon black and the rubber are mixed, the carbon black is only physically dispersed on the rubber matrix.

Accordingly, when stress is applied to a tire made of a rubber composition and strain is continuously generated, the physically dispersed carbon black particles are disengaged from each other or deviated from the original position in order to maintain elasticity of the rubber, .

To solve this problem, a technique of adding sulfur (sulfur) capable of forming a bridge with rubber to a rubber composition has been introduced, but sulfur only forms a cross-link (chemical bond) between adjacent rubber molecules, There is a limit in solving the above-mentioned problems because it does not form a chemical bond with carbon black.

As an alternative, a method of replacing carbon black with silica or introducing a silane group onto the surface of carbon black has been disclosed, but an expensive coupling agent is required for a crosslinking reaction through silica or a silane group, and an alcohol byproduct is generated as a result of the crosslinking reaction There is a problem.

The object of the present invention is to provide a method for modifying functional groups for introducing functional groups for mediating chemical bonding as well as physical bonding between rubber molecules and carbon black in the rubber composition to the surface of carbon black do.

It is another object of the present invention to provide a modification method for introducing a functional group capable of mediating a crosslinking reaction between rubber molecules onto the surface of carbon black.

It is another object of the present invention to provide a pretreatment method for introducing a functional group capable of mediating a crosslinking reaction between rubber molecules onto the surface of carbon black.

In addition, the present invention provides a surface modification method that can be applied to the production process of carbon black, so that it is possible to modify the surface of carbon black without any additional process, thereby reducing the difficulty and cost of the production process The purpose.

According to an aspect of the present invention, there is provided a method for introducing a functional group capable of mediating chemical bonding with rubber molecules into the surface of carbon black by performing surface modification immediately with preparation of carbon black Can be provided.

Specifically, a method for modifying the surface of carbon black according to an embodiment of the present invention may include the following steps.

(a) pre-treating carbon black in a fine state in an oxidizing gas atmosphere;

(b) mixing the pretreated carbon black with water to prepare a mixture;

(c) pelletizing the carbon black in the mixture; And

(d) heat-treating the pelletized carbon black while supplying a mixed gas containing a gaseous sulfur compound to obtain a carbon black into which an in-surface sulfur-containing functional group is introduced.

According to one embodiment of the present invention, carbon black (differential state) is synthesized from a hydrocarbon-based raw material and then pre-treated.

The pretreatment of step (a) can be carried out at room temperature, for example, at a temperature of from 20 to 35 DEG C, and a first-order reforming takes place at the surface of the carbon black through pretreatment.

The step (a) may be carried out under at least one oxidizing gas atmosphere selected from oxygen, ozone, air and NO ₂ , and the proportion of the oxygen-containing functional groups in the surface of the carbon black through the pretreatment may be increased.

In one embodiment, the pretreatment is preferably carried out such that the content of oxygen-containing functional groups in the surface of the carbon black is 0.1 to 1.0 meq / g.

The content of the oxygen-containing functional groups introduced into the surface of the carbon black through the pretreatment in the step (a) can be confirmed by the weight ratio of the gas generated from the functional groups of the surface of the carbon black measured by the thermal desorption analysis method.

The weight ratio of gaseous CO / CO ₂ / H ₂ generated by the thermal desorption analysis of the pretreated carbon black according to step (a) may be in the range of 5/1/1 to 20/10/1.

Subsequently, step (b) is a step of mixing the preprocessed carbon black in the finely divided state according to step (a) with a wet pelletization precursor, and step (c) .

Finally, the heat treatment in step (d) can be performed at a temperature of 160 to 500 ° C, and the heat treatment completely removes moisture from the carbon black, and at the same time, the secondary modification occurs at the surface of the carbon black.

The heat treatment in step (d) is carried out under an atmosphere in which at least one sulfur compound is selected from H ₂ S, SO _2, and elemental sulfur.

At this time, the mixed gas contacting the pretreated carbon black is preferably supplied at a gas hourly space velocity of 600 to 3,000 ^hr < ^{-1 &} gt ;, and the concentration of the sulfur compound on the gaseous mixture in the mixed gas is 500 to 1,000 mg / Nm < ^{3 &} gt ;.

At least one sulfur-containing functional group selected from a polysulfide group including a monosulfide group, a disulfide group and at least three sulfur atoms may be present on the surface of the carbon black that has been subjected to the heat treatment in the step (d) Monosulfide groups and / or disulfide groups may predominantly be present.

Also, according to an embodiment of the present invention, the content of sulfur in the carbon black that has been subjected to the heat treatment may be 3 wt% or more.

The surface of the surface-modified carbon black according to the present invention is first pretreated, and then a functional group capable of mediating the crosslinking reaction between the rubber molecules is introduced. As a result, a more uniform and high content of crosslinking agent This is an advantage.

In addition, functional groups capable of mediating a crosslinking reaction between rubber molecules are uniformly introduced onto the surface of the surface-modified carbon black according to the present invention. Thus, carbon black in the rubber matrix through the cross- The crosslinking density between the rubber molecules mediated by carbon black can be increased and the tensile strength of the tire can be increased.

In addition, since the chemical bond between the carbon black and the rubber molecule can be mediated through the functional groups present on the surface of the surface-modified carbon black according to the present invention, the bonding force between the rubber molecule and the carbon black can be further improved, As a result, the resistance against the stress applied to the tire continuously, that is, the wear resistance can be improved.

Certain terms are hereby defined for convenience in order to facilitate a better understanding of the present invention. Unless otherwise defined herein, scientific and technical terms used in the present invention may have the meanings commonly understood by one of ordinary skill in the art.

Also, unless the context clearly indicates otherwise, the singular form of the term includes plural forms thereof, and the plural forms of terms may include singular forms thereof.

Hereinafter, a method for modifying the surface of carbon black according to an embodiment of the present invention will be described in detail.

According to one aspect of the present invention, there can be provided a method for introducing functional groups capable of mediating chemical bonding with rubber molecules into the surface of carbon black by performing surface modification immediately with preparation of carbon black.

Specifically, a method for modifying the surface of carbon black according to an embodiment of the present invention may include the following steps.

(a) pre-treating carbon black in a fine state in an oxidizing gas atmosphere;

(b) mixing the pretreated carbon black with water to prepare a mixture;

(c) wet-pelletizing the carbon black in the mixture; And

(d) heat treating the pelletized carbon black while supplying a gaseous gas comprising a gaseous sulfur compound to obtain a carbon black into which an in-surface sulfur-containing functional group has been introduced.

According to one embodiment of the present invention, carbon black (differential state) is synthesized from a hydrocarbon-based raw material and then pre-treated.

Herein, the carbon black in the finely divided state means the carbon black before being pelletized.

The pretreatment of step (a) can be carried out at room temperature, for example, at a temperature of from 20 to 35 DEG C, and a first-order reforming takes place at the surface of the carbon black through pretreatment.

Step (a) can be carried out in an oxidizing gas atmosphere and the proportion of oxygen-containing functional groups in the surface of the carbon black can be increased through the pretreatment of step (a).

Here, the oxidizing gas is a gas containing an oxidizing substance, and may be at least one selected from oxygen, ozone, air and NO ₂ . Further, the above-mentioned oxidizing gas and at least one mixed gas selected from hydrogen, nitrogen and argon may be used.

The primary modification means an oxidative modification which takes place on the surface of the carbon black, and the oxidative modification can increase the proportion of oxygen-containing functional groups in the surface of the carbon black. For example, oxidative modification can occur in such a way that hydrogen is replaced by oxygen from the C-H bond present in the surface of the carbon black, or an oxygen-containing functional group is introduced instead of hydrogen.

The oxygen-containing functional groups include an aldehyde group, a ketone group, a carboxyl group, and a hydroxyl group, and may further include oxygen-containing functional groups of other polarities which can be introduced through oxidative modification occurring in an oxidizing gas atmosphere.

When the pre-treatment temperature is less than 20 占 폚, the oxidative modification rate at the surface of the carbon black is slow, and the ratio of the oxygen-containing functional group on the surface of the carbon black can not be sufficiently increased.

The oxygen-containing functional groups introduced into the surface of the carbon black through the oxidative modification according to the pretreatment can be replaced with sulfur-containing functional groups through subsequent modification according to the heat treatment. Therefore, when the oxygen-containing functional groups are not sufficiently introduced into the surface of the carbon black through the oxidative modification due to the pretreatment, it may be difficult to introduce sufficient sulfur-containing functional groups on the surface of the carbon black even after the heat treatment.

On the other hand, when the pretreatment temperature exceeds 35 ° C, the oxidation reforming speed of the carbon black surface increases as the temperature rises, but the degree is not large compared with the room temperature. Therefore, the temperature increase is unnecessary considering the economical aspect, because the oxidation reforming effect is smaller than the energy applied to increase the temperature.

Therefore, it is preferable that the pretreatment is carried out in the above-mentioned temperature range in order to increase the proportion of the oxygen-containing functional groups in the surface of the carbon black and to maintain the surface stability of the carbon black.

Further, in one embodiment, it is preferable that the pretreatment is carried out such that the content of oxygen-containing functional groups in the surface of the carbon black is 0.1 to 1.0 meq / g. The method of measuring the content of oxygen-containing functional groups in the surface of carbon black can be carried out by a method conventionally used for quantitatively analyzing functional groups containing specific elements.

If the content of the oxygen-containing functional groups introduced into the surface of the carbon black through the first pretreatment is less than 0.1 meq / g, the introduction of sufficient sulfur-containing functional groups on the surface of the carbon black may be difficult even after the heat treatment.

On the other hand, when the content of the oxygen-containing functional groups introduced into the surface of the carbon black through the first pretreatment exceeds 1.0 meq / g, the content of the sulfur-containing functional groups in the carbon black becomes too large, There is a problem that the vulcanization time becomes too fast in the compound manufacturing process and it is difficult to control.

The content of the oxygen-containing functional groups introduced into the surface of the carbon black through the pretreatment in the step (a) can be confirmed indirectly through the weight ratio of the gas generated from the functional groups of the surface of the carbon black measured by the thermal desorption analysis method.

The weight ratio of gaseous CO / CO ₂ / H ₂ generated by the thermal desorption analysis of the pretreated carbon black according to step (a) may be in the range of 5/1/1 to 20/10/1.

The above-mentioned content ratio of the gas finally indicates the degree of first modified by the step (a), that is, the degree of introduction of the oxygen-containing functional group, and the fact that the ratio of CO and / or CO ₂ is relatively higher than the ratio of H ₂ It means that the proportion of the oxygen-containing functional groups in the surface of the carbon black is increased.

In addition, the carbon black of the surface of the oxygen-in as fast than the substitution rate of a containing functional groups gaseous CO and / or CO ₂ - sulfur-containing functional group substituted speed of the contained functional group is the carbon black surface in CH H of sulfur in combination The similar ratio of H ₂ means that the introduction of oxygen-containing functional groups in the surface of carbon black is not sufficiently achieved.

When the ratio of gas CO and / or CO ₂ exceeds H ₂ ratio of 20/10/1, since the content of oxygen-containing functional groups in the carbon black is large, the content of sulfur introduced into the carbon black by the heat treatment is too large There is a problem that vulcanization time becomes too fast and control is difficult when a compound is produced using carbon black.

The wet-pelletized carbon black through step (c) is present in the presence of water and is subjected to a heat treatment (drying) process (step (d)) in a separate dryer to remove water to remove carbon black ≪ / RTI > At this time, the surface modification process for the carbon black may be performed simultaneously with the drying process.

The heat treatment in step (d) may be carried out at a temperature of 160 to 500 ° C, preferably 250 to 400 ° C, and the heat treatment completely removes water from the carbon black, and at the same time, the secondary modification occurs on the surface of the carbon black.

The heat treatment is carried out in an atmosphere in which at least one sulfur compound selected from a sulfur source that can be supplied to the gas phase, for example, H ₂ S, SO ₂ and sulfur is present, The present oxygen-containing functional groups may be substituted with sulfur-containing functional groups.

As the sulfur-containing functional group, there may be at least one sulfur-containing functional group selected from a polysulfide group including a monosulfide group, a disulfide group and three or more sulfur, preferably a monosulfide group and / or disulfide There can be mainly a group.

For example, an oxygen-containing functional group such as an aldehyde group, a ketone group, a carboxyl group and a hydroxyl group may be substituted with a sulfur-containing functional group such as a monosulfide group and a disulfide group, wherein the aldehyde, As the sulfur is substituted with the sulfur-containing functional group, it is released from the carbon black in the form of carbon monoxide (CO) gas, and in the case of the carboxyl group, it is released in the form of carbon dioxide (CO ₂ ) gas.

In addition, hydrogen may be replaced by sulfur from the CH bonds present in the surface of the carbon black through secondary modification, or a sulfur-containing functional group may be introduced instead of hydrogen. At this time, as the hydrogen is substituted with the sulfur-containing functional group, it is released from the carbon black in the form of hydrogen (H ₂ ) gas.

At this time, the mixed gas contacting the pretreated carbon black is preferably supplied at a gas hourly space velocity of 600 to 3,000 ^hr < ^{-1 &} gt ;, and the concentration of the sulfur compound on the gaseous mixture in the mixed gas is 500 to 1,000 mg / Nm < ^{3 &} gt ;.

If the gas hourly space velocity of the mixed gas is less than 600 hr ^-1 , the secondary reforming may not be sufficiently performed. That is, the rate at which the hydrogen of the oxygen-containing functional group or the CH bond existing in the surface of the carbon black is substituted with the sulfur-containing functional group may be slow because of the slow rate at which the gaseous sulfur compound is fed.

On the other hand, a gas space velocity of the mixed gas (Gas Hourly Space Velocity) 3,000hr ^- if more than ^1, more sulfur-exists the possibility of the reaction efficiency of the gas containing the carbon black decreases.

The content of sulfur in the surface-modified carbon black through the above-described steps may be 3 wt% or more.

As described above, the step (d) in which the heat treatment is performed is a step of removing water from the carbon black containing moisture after wet pelletization and simultaneously modifying the surface of the carbon black. The drying step of the carbon black and the surface modification step So that the difficulty and cost of the manufacturing process can be reduced.

Hereinafter, specific embodiments of the present invention will be described. However, the embodiments described below are only intended to illustrate or explain the present invention, and thus the present invention should not be limited thereto.

Surface Modification Method of Carbon Black

Example  One

Step (a): Carbon black (N234 grade) in a finely pulverized state was pretreated with an oxidizing gas treatment reactor located on the upstream side of the pelletizer. The oxidizing gas treatment reactor was a rotary kiln type reactor, and the reaction temperature was set at room temperature, the reactor rotation speed was 20 rpm, and the concentration of ozone in oxygen was 90 mg / Nm ³ (4.2 vol%). The total amount of ozone supplied was 9.072 mg / cbg, and the carbon black in the pulverized state was pretreated for 2 hours.

Step (b) and (c): Carbon black in the oxidation-modified and finely pulverized state was mixed with water having the same weight and then pelletized in a wet pelletizer for 1 hour.

Step (d): The pulverized (pelletized) carbon black was put into a dryer for moisture drying and surface modification. The temperature in the dryer was 250 DEG C and the residence time was 2 hours. A part of the flue gas separated from the bag filter was used as a mixed gas and an elemental sulfur vapor was used as a gaseous sulfur compound. At this time, the gas mixture in contact with the pre-treated carbon black concentration of the sulfur compound on the inner gas was supplied to the gas space velocity (Gas Hourly Space Velocity) of 2,000hr ^-1, the mixed gas was set to 700 mg / Nm ^3.

Example  2

The surface of the carbon black was modified under the same conditions as in Example 1, and pre-treatment with ozone was performed for 1 hour.

Example  3

The surface of the carbon black was modified in the same manner as in Example 1, and the total amount of ozone supplied during the pretreatment was set to 18.144 mg / Cbg.

Example  4

The surface of the carbon black was modified in the same manner as in Example 1 except that the gas hourly space velocity of the mixed gas in the step (d) was set to 4,000 hr ^-1 .

Comparative Example  One

The surface of the carbon black was modified in the same manner as in Example 1, but step (d) was not performed.

Comparative Example  2

The surface of the carbon black was modified in the same manner as in Example 1, but the step (a) was not performed.

Comparative Example  3

The surface of the carbon black was modified in the same manner as in Example 1 except that the gas hourly space velocity of the mixed gas in the step (d) was set to 500 hr ^-1 .

surface Reformed  Composition analysis results of carbon black

division C (wt%) H (wt%) N (wt%) S (wt%) O (wt%) Example 1 95.41 0.11 0.19 3.45 0.21 Example 2 95.89 0.12 0.19 3.03 0.23 Example 3 94.25 0.10 0.17 4.59 0.12 Example 4 94.71 0.11 0.16 4.55 0.19 Comparative Example 1 97.13 0.23 0.21 0.45 1.34 Comparative Example 2 96.6 0.25 0.22 1.05 0.6 Comparative Example 3 96.09 0.17 0.18 1.50 0.42

(Content of elements contained in the surface-modified carbon black was converted into weight ratios) of the surface-modified carbon black according to Examples 1 to 3 and Comparative Examples 1 to 4, In Example 3, it was confirmed that the content of sulfur was 3 wt% or more.

On the other hand, in Comparative Examples 1 and 2, which were not subjected to the pretreatment in the presence of an oxidizing gas or to the heat treatment in the presence of a gaseous sulfur compound, it was confirmed that the sulfur content in the carbon black was only about 1 wt%.

It was also confirmed that, even if the surface was modified in the same manner as in Example 1, the surface modification of the carbon black was insufficiently performed when the gas space velocity of the mixed gas was too low.

In addition, in the case of Example 4 where the gas space velocity is too high, surface modification of the carbon black occurs sufficiently, but there is no great difference in the sulfur content with Example 3, so that the gas space velocity of the gas mixture is 2000 h ^-1 or more, As shown in FIG.

surface Reformed  Comparison of physical properties of rubber compositions containing carbon black

Rubber compositions comprising surface-modified carbon black according to Examples 1 to 3 and Comparative Examples 1 to 4 were prepared in the following composition.

ingredient Amount (pph) added per 100 parts by weight caoutchouc 100 Surface modified carbon black 50 Zinc oxide 5 Stearic acid 3 sulfur 2.5 Accelerator (CBS) 0.6

Rubber specimens were prepared using the rubber compositions prepared according to Table 2, and the properties of the rubber specimens were measured based on the following evaluation items in accordance with ASTM regulations.

As evaluation items,

Abrasion resistance (measured through actual vehicle evaluation on dry roads for 320 / 710R18 F200 standard tires),

Dynamic viscoelasticity (0 deg. C, 60 deg. Tan < 2 >) (G 'and G' tan delta measured at -60 deg. C to 80 deg. C under 10 Hz frequency in a 0.5%

300% elastic modulus as measured by tensile properties (as measured by the ISO 37 standard),

Respectively.

division Abrasion resistance 0 deg. 60 deg. Elastic modulus
(M300) Example 1 115 110 93 100 Example 2 110 105 97 101 Example 3 125 115 85 103 Comparative Example 1 100 100 100 100 Comparative Example 2 105 100 105 90 Comparative Example 3 107 103 98 94

The abrasion resistance is a physical property related to the life of the tire. The measured value of Comparative Example 1, which is not pretreated, is taken as 100, and the measurement values of Examples and Comparative Examples are indexed as shown in Table 3 based on this. The abrasion resistance is superior to the reference value.

The dynamic viscoelasticity represents the changing ratio of the viscosity / elasticity of the compound to the temperature change.

The 0 deg. Tan delta is an index indicating a wet slip prevention behavior called wet grip. The higher the tan δ value at 0 ° C, the better the wet-slip behavior.

In addition, tan? Of 60 占 폚 is an index of rolling resistance, and the larger the rotational resistance, the lower the fuel efficiency. Therefore, the lower the tan δ value at 60 ° C, the lower the rolling resistance and improve the fuel efficiency.

The elastic modulus tends to increase the abrasion resistance when the modulus of elasticity is high, but it is not necessarily proportional, so it is important to maintain a certain level of modulus of elasticity because the physical properties of the rubber composition affect abrasion resistance and dynamic viscoelasticity.

Referring to Examples 1 to 3, it was confirmed that the braking performance on a dry road surface was excellent without deterioration of wear and grip performance while maintaining a certain level of elastic modulus as compared with Comparative Examples.

As described above, since the surface of the surface-modified carbon black according to the present invention is preliminarily pretreated, a functional group capable of mediating a crosslinking reaction between rubber molecules is introduced, and a more uniform and high content It is possible to introduce a crosslinking reaction mediator.

In addition, functional groups capable of mediating a crosslinking reaction between rubber molecules are uniformly introduced onto the surface of the surface-modified carbon black according to the present invention. Thus, carbon black in the rubber matrix through the cross- The crosslinking density between the rubber molecules mediated by carbon black can be increased and the tensile strength of the tire can be increased.

In addition, since the chemical bond between the carbon black and the rubber molecule can be mediated through the functional groups present on the surface of the surface-modified carbon black according to the present invention, the bonding force between the rubber molecule and the carbon black can be further improved, As a result, the resistance against the stress applied to the tire continuously, that is, the wear resistance can be improved.

In addition, when the surface-modified carbon black according to the present invention is used to manufacture a tire, it has an advantage that it maintains a certain level of elastic modulus and is excellent in braking performance on a dry road surface without deterioration of wear and grip performance.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit of the invention as set forth in the appended claims. The present invention can be variously modified and changed by those skilled in the art, and it is also within the scope of the present invention.

Claims (12)

(a) pre-treating carbon black in a fine state in an oxidizing gas atmosphere;
(b) mixing the pretreated carbon black with water to prepare a mixture;
(c) pulverizing the carbon black in the mixture; And
(d) heat-treating the ground carbon black while supplying a mixed gas containing a gaseous sulfur compound to obtain a carbon black into which an in-surface sulfur-containing functional group is introduced;
Of the carbon black.
The method according to claim 1,
Wherein the pretreatment of step (a) is carried out at a temperature of from 20 to < RTI ID = 0.0 > 35 C. &
A method for surface modification of carbon black.
The method according to claim 1,
Wherein the oxidizing gas is at least one selected from oxygen, ozone, air and NO ₂ ,
A method for surface modification of carbon black.
The method according to claim 1,
Wherein the ratio of the oxygen-containing functional groups in the surface of the carbon black through the pretreatment is increased,
A method for surface modification of carbon black.
5. The method of claim 4,
Wherein the oxygen-containing functional group is at least one selected from an aldehyde group, a ketone group, a carboxyl group and a hydroxyl group,
A method for surface modification of carbon black.
5. The method of claim 4,
The content of oxygen-containing functional groups in the surface of the pretreated carbon black is 0.1 to 1.0 meq / g,
A method for surface modification of carbon black.
The method according to claim 1,
Wherein the heat treatment of step (d) is carried out at a temperature of from 160 to 500 ° C,
A method for surface modification of carbon black.
The method according to claim 1,
Wherein the sulfur compound is at least one selected from H ₂ S, SO ₂ ,
A method for surface modification of carbon black.
The method according to claim 1,
Wherein the mixed gas contacting the pretreated carbon black is supplied at a gas hourly space velocity of 600 to 3,000 ^hr < " ¹ &
A method for surface modification of carbon black.
The method according to claim 1,
Wherein the concentration of the sulfur compound in the mixed gas is 500 to 1,000 mg / Nm ³ ,
A method for surface modification of carbon black.
The method according to claim 1,
Wherein at least one sulfur-containing functional group selected from a polysulfide group containing a monosulfide group, a disulfide group, and at least three sulfur atoms is present on the surface of the heat-treated carbon black,
A method for surface modification of carbon black.
The method according to claim 1,
The content of sulfur in the heat-treated carbon black is 3 wt% or more,
A method for surface modification of carbon black.