JP2005272729A - Method for manufacturing carbon black for tire tread - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing carbon black qualified in high compatibility between wear resistance and low heat generation when used in a tire tread formulation, particularly aiming at surface properties of the carbon black. <P>SOLUTION: This method for manufacturing carbon black satisfies following formulas (1) and (2): (1) 2.00≤α≤9.00, (2) -2.5×α+85.0≤β≤90.0, wherein α=t<SB>1</SB>×T<SB>1</SB>, β=t<SB>2</SB>×T<SB>2</SB>, t<SB>1</SB>(second) represents a residence time of a crude hydrocarbon from introduction of the hydrocarbon into a high temperature gas flow up to introduction of a quenching medium, T<SB>1</SB>(°C) represents an average reaction temperature in this space, t<SB>2</SB>(second) represents a residence time of a reactive gas flow from introduction of the quenching medium up to passage of the medium through a reaction termination zone, T<SB>2</SB>(°C) represents an average reaction temperature in this space. The carbon black is provided using the method. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing carbon black capable of imparting high wear resistance and excellent low heat buildup that are preferable as a rubber composition for a tire tread when a rubber component is blended.

  Carbon black is produced by spraying raw material hydrocarbons into a high-temperature combustion gas generated in a furnace and / or externally generated and introduced into the furnace under strictly controlled conditions. It is an industrially useful raw material produced by thermal decomposition or incomplete combustion, and dramatically improves mechanical properties, especially tensile strength, wear resistance, etc., for the composition with rubber. Because it has a unique property that it can be used, it is widely used as a filling and reinforcing agent for various rubber products including tires, and it is used for a long period of about 100 years, and it uses the blackness that is its color feature. It is also used as a raw material for various paints and inks.

  Carbon black for rubber compounding depends on its physicochemical properties, that is, the unit particle diameter, the surface area per unit weight (specific surface area), the degree of particle connection (structure), surface properties, etc. Since it has a great influence on performance, carbon black having different characteristics is selectively used depending on required rubber performance, environment in which it is used, and the like.

  The rubber composition used for the tire contact surface (tread portion) is excellent in resistance to abrasion (wear resistance) due to contact with the road surface at high speed rotation and at the same time due to repeated deformation caused by contact with the road surface. Hysteresis characteristics that greatly affect the heat generation characteristics of rubber compositions are also an important factor, but it is known that these two characteristics are contradictory to each other, that is, if one of the characteristics is improved, the other characteristics decrease. This is a major issue.

  When carbon black for tire tread blending is used to improve the wear resistance of the rubber composition, for example, when carbon black having a larger specific surface area or structure is adopted, the wear resistance and heat generation characteristics are mutually In order to solve this problem, carbon black having various characteristics has been proposed.

  For example, inventions (Patent Documents 1 and 2, etc.) have been proposed that focus on constituent elements other than carbon and surface activity contained in carbon black and specify the sum or ratio of the amount of hydrogen and the amount of oxygen on the surface of carbon black. .

  In addition, by reducing the solvent extraction component (heavy tar component: polycyclic aromatic hydrocarbon component, etc.) with pyridine or toluene contained in carbon black, reinforcement of compounded rubber composition by improving dispersion in rubber, etc. Inventions (such as Patent Documents 2 and 3) that improve the properties and wear resistance have been proposed.

  The reaction process in which carbon black is generated by pyrolysis or incomplete combustion of raw material hydrocarbons introduced into a high-temperature gas stream is extremely complicated and has not been elucidated in detail yet. If present, a carbon black containing a low aromatic hydrocarbon content with a UV absorbance of 0.15 or less is obtained by moving the rapid refrigerant introduction position for stopping the carbon black formation reaction away from the throttling position and / or reducing the amount of water for stopping the reaction. (Patent Document 4). However, the present invention relates to a method for producing a carbon black for coloring, and since long-term exposure of the formed carbon black to a high temperature atmosphere will reduce the surface activity, This is a manufacturing method in which characteristics such as wear resistance and low heat build-up are not considered at all.

The invention specifying the reaction residence time from the introduction of the raw material oil into the high-temperature gas flow until the introduction of the rapid refrigerant is disclosed in Patent Document 5, and the first reaction that does not stop the reaction within 0.002 seconds after the introduction of the raw material oil. Is described, and then a process for producing carbon black is described in which the reaction is stopped further by lowering the temperature further downstream.
However, the values of toluene discoloration (toluene coloring transmittance in the present invention) shown in the table of the present invention are 41 to 78%, which are all low, which is a polycyclic aromatic hydrocarbon contained in carbon black. This means that the amount of this component is large, and since this component has little or no interaction with rubber, improvement in properties such as wear resistance or low heat build-up at the time of rubber blending cannot be expected.

Japanese Patent Laid-Open No. 4-108837 JP 10-36703 A JP-A-9-40883 JP-A-8-269360 Japanese Examined Patent Publication No. 7-49541

  Under such circumstances, the object of the present invention is to provide a method for producing carbon black suitable for tire tread rubber blending, which is suitable for achieving both high wear resistance and low heat build-up, and in particular, the surface properties of carbon black. It is to provide.

As a result of intensive studies in order to solve the above problems, the present inventors, as a method for producing carbon black of the present invention, include a reactor in which a combustion zone, a reaction zone, and a reaction stop zone are arranged on the same axis. Used to generate high-temperature combustion gas by combustion of hydrocarbons for fuel in the combustion zone, and then continuously introduce the raw material hydrocarbon into the high-temperature combustion gas stream in the reaction zone, and the raw material carbonization by incomplete combustion or thermal decomposition reaction In the carbon black production method comprising: forming a reaction gas stream containing carbon black converted from hydrogen; and then quenching the reaction gas stream in a reaction stop zone to terminate the reaction. The residence time from the introduction of the refrigerant to the introduction of the rapid refrigerant is t ₁ (seconds), the average reaction temperature in this space is T ₁ (° C.), and Assuming that the residence time of the reaction gas flow containing carbon black from the introduction of the quenching medium to the passage of the reaction stop zone is t ₂ (seconds) and the average reaction temperature in this space is T ₂ (° C.), the following (1 ) And (2) are satisfied by the constitution.
(1) 2.00 ≦ α ≦ 9.00
(2) -2.5α + 85.0 ≦ β ≦ 90.0
(Wherein, α = t ₁ × T ₁ , β = t ₂ × T ₂ is represented)

Here, α and β are (1) 3.00 ≦ α ≦ 8.00.
(2) It is more preferable to satisfy the range of −2.5 × α + 85.0 ≦ β ≦ 86.0.

Here, each band in the present invention will be described.
The combustion zone is a region where a high-temperature gas flow is generated by the reaction of fuel and air, and this downstream end is the point at which the feedstock is introduced into the reactor (the most upstream when introduced at a plurality of positions). Side), for example, when the feedstock is introduced from 8C, it indicates the upstream side (left side in the figure).
The reaction zone refers to the rapid water spraying means a to y in the reaction continuation / cooling chamber 10 from the point where the raw material hydrocarbon is introduced (in the case of a plurality of positions, the most upstream side). It can be inserted and removed within the range of 10 and the use position is selected depending on the type of product to be produced and characteristics). That is, when feedstock is introduced at 8C and water is introduced at h, the region between these becomes the reaction zone.
The reaction stop zone refers to a zone below (on the right side in the figure) below the point at which the quench water injection spray means is operated.

In the carbon black production method of the present invention, it is a necessary condition that the exposure of carbon black to heat in the reaction zone and the reaction stop zone, in other words, α and β values representing the magnitude of thermal history satisfy the above range. In order to adjust the average reaction temperature, air and gas such as oxygen or hydrocarbon combustion gas are placed in the range from the raw material hydrocarbon introduction position to the rapid refrigerant body introduction position and / or the range from the rapid refrigerant body introduction position to the final reaction step. It can be introduced and added. Further, in order to calculate the average temperature T ₁ and T ₂ in each step, at least two locations in each step, preferably it is preferable to measure the temperature of 3-4 places.

なお、原料油の分解反応および急冷媒体による体積増加は無視するものとする。 The residence time is calculated by calculating the volume of the combustion gas fluid by a known thermodynamic calculation method using a combustion reaction product of fuel and air introduced into the combustion zone, and then calculating the residence time.

Note that the increase in volume due to the decomposition reaction of the feedstock oil and the rapid cooling medium is ignored.

The present invention is described in detail below. The method for producing carbon black of the present invention uses the residence time elapsed after the initial contact between the high temperature combustion gas and the raw material hydrocarbon from the raw material hydrocarbon introduction position to the rapid refrigerant body introduction position as t ₁ (seconds). The average reaction temperature is T ₁ (° C.), the residence time of the reaction gas flow from the introduction of the rapid refrigerant to the passage of the reaction stop zone is t ₂ (seconds), and the average reaction temperature T ₂ (° C.) in this space is Then, these products (indexes indicating the degree of thermal history) indicating how much heat is received at what temperature in each process are newly defined, and these values are 2.00 ≦ α ≦ 9.00, −2.5 × α + 85.0 ≦ β ≦ 90.0 (where α = t ₁ × T ₁ , β = t ₂ × T ₂ ) Optimize thermal history of carbon black during and / or generation By doing so, it is possible to avoid deterioration in mechanical properties, particularly wear resistance, of the rubber composition, and as a result, it has been found that carbon black for compounding tire tread rubber can achieve both high wear resistance and low heat generation. The invention has been completed.

In the method for producing carbon black of the present invention, the residence time from the raw material hydrocarbon introduction position to the rapid refrigerant introduction position is t ₁ (seconds), the average reaction temperature in the space is T ₁ (° C.), and the product thereof is α When the residence time from the rapid refrigerant introduction to the passage of the reaction stop zone is t ₂ (seconds), the average reaction temperature in the space is T ₂ (° C.), and the product thereof is β, 2.00 ≦ α ≦ 9 0.00 and -2.5 × α + 85.0 ≦ β ≦ 90.0 are necessary conditions for obtaining the target carbon black. Carbon black obtained under a production condition where the product α of t ₁ and T ₁ is less than 2.00 has a toluene coloring transmittance of less than 90%, or a monochlorobenzene extraction amount of more than 0.15%, and is contained in the carbon black. Many polycyclic aromatic hydrocarbon components are present, and this component is not preferable because it does not give sufficient reinforcement to the rubber and wear resistance decreases. A more preferable α value is 3.00 or more. On the other hand, carbon black obtained under production conditions in which α exceeds 9.00, that is, under the condition of receiving an excessive thermal history in the carbon black reaction zone, has a hydrogen release rate of a relational value [0.260-0. .000625 × (CTAB)], which is not preferable because the wear resistance of the rubber composition decreases and the heat generation of the rubber composition increases. A more preferable α value is 8.00 or less.

Even if the α value satisfies the above-mentioned range, the product β of t ₂ and T ₂ is less than the value of the relational expression [−2.5 × α + 85.0], that is, the reaction occurs after the rapid refrigerant is introduced. The carbon black obtained when the heat history up to the stop zone is small has an excessive toluene coloring transmission of less than 90%, or an extraction amount of monochlorobenzene of more than 0.15%, and conversely an excess of β value exceeding 90.0. Carbon black obtained under production conditions that receive a thermal history has a hydrogen release rate equal to or lower than the relational expression value [0.260-0.000625 × (CTAB)], which is not preferable for the same reason as described above. A more preferable β value is 86.0 or less.

Further, the method for producing carbon black of the present invention includes a range from the raw material hydrocarbon introduction position to the quenching medium introduction position and / or in order to adjust the average reaction temperature T ₁ or T ₂ in the reaction zone or the reaction stop zone. A gas body such as air, a mixture of oxygen and hydrocarbons, or a combustion gas resulting from a combustion reaction thereof may be introduced and added into a space ranging from the position where the quenching medium is introduced to the downstream end of the reaction stop zone, and the average reaction temperature T ₂ For this adjustment, the amount of introduced quenching medium, for example, water at the quenching medium introduction position may be appropriately controlled.

  According to the present invention, in the method for producing carbon black, by producing it under a specific range of reaction conditions, it is possible to achieve both high wear resistance and low heat buildup for use in tire tread rubber blending. It is possible to provide an industrially useful carbon black characterized by a balance between the ratio and the amount of contained polycyclic aromatic hydrocarbons.

  Examples of the present invention will be described in detail below in comparison with comparative examples, but the scope of the present invention is not limited thereby.

Examples and Comparative Examples Using a carbon black reactor (FIG. 1) shown in FIGS. Carbon blacks 1-9 were produced.

An oxygen-containing gas introduction cylinder (inner diameter 250 mmφ, long) having a rectifying plate 5 for rectifying the oxygen-containing gas introduced from the outer periphery of the reactor head inside the combustible fluid introduction chamber (inner diameter 450 mmφ, length 400 mm) 2 300 mm) 4 and a fuel introducing means at its central axis, and the downstream side of the cylinder is a converging chamber 7 (upstream end inner diameter 370 mmφ, downstream end inner diameter 80 mmφ, convergence angle 5.3 °) 7, and the converging chamber 7, four separate feed oil spray ports (8B-1, 8B-2, 8B-3, 8B-4) as illustrated on the 8B plane in FIG. 2 are installed on the same plane. It has a raw material oil introduction chamber 9 including a raw material oil spraying port (8A to 8D) that forms a flat surface, and this downstream side is equipped with 25 quenching water injection spraying means (a to y) for reaction continuation and cooling. Chamber (inner diameter 160mmφ, It is 7500 mm) made of 10 entirely using the reactor covered with refractory.
Here, the name of the reaction continuation / cooling chamber 10 is used because the reaction zone is from the raw material introduction time to the operation time of the quenching water injection spraying means for stopping the reaction, and the reaction stop zone thereafter is the quench water. This is because the introduction position may move depending on the required carbon black performance.
For example, in FIG. 1, when the feedstock oil introduction position is 8C and the coolant introduction position is f, the reaction zone is between 8C and f.

  Moreover, in order to monitor the temperature in the reaction apparatus, an apparatus having a structure in which thermocouples can be inserted into at least two places in each of the reaction zone and the reaction stop zone was used.

A heavy oil having a specific gravity of 0.8622 (15 ° C / 4 ° C) was used as the fuel, and a heavy oil having the properties shown in Table 1 was used as the feedstock oil. In addition, 0.8622 (15 ° C / 4 ° C) indicates that the ratio of the mass of heavy oil A at 15 ° C to the mass of water at 4 ° C is 0.8622.

  Using the carbon black reactor, carbon black was produced under the operating conditions that satisfy the requirements of the invention shown in Tables 2 to 3 and the operating conditions that were removed.

  The carbon black production conditions described in Tables 2 to 3 are as follows: the total amount of air introduced, the amount of introduced raw material oil and the temperature, the amount of introduced fuel oil, the amount of fuel introduced, Adjust conditions such as the residence time from the hydrocarbon introduction position to the rapid refrigerant introduction position, the average reaction temperature in that space, the residence time from the introduction of the sudden refrigerant to the reaction stop zone, and the average reaction temperature in that space It is manufactured.

  Tables 4 to 5 show the physicochemical characteristics of the carbon blacks produced under the operating conditions shown in Tables 2 to 3.

  Each characteristic of the carbon black described in the present invention is measured by the following method.

(1) DBP absorption amount, 24M4 DBP absorption amount It is measured by the method described in JIS K6217-4: 2001, and is expressed in ml of dibutyl phthalate (DBP) absorbed per 100 g of carbon black.

(2) CTAB adsorption specific surface area It is measured by the method described in JIS K6217-3: 2001, and is expressed as a specific surface area m ² / g per unit weight.

(3) Toluene coloring transmittance Measured by the method described in Item B method of JIS K6218: 1997, and displayed as the transmittance (%) of the treatment liquid when the transmittance of pure toluene is 100%. . A larger number means a lower degree of toluene contamination, that is, less undecomposed aromatic hydrocarbon components.

(4) Hydrogen release rate (a) A carbon black sample is dried in a constant temperature dryer at 105 ° C. for 1 hour and cooled to room temperature in a desiccator.
(B) About 10 mg is precisely weighed in a tubular sample container made of tin, and crimped and sealed.
(C) The amount of hydrogen gas generated when heated at 2000 ° C. for 15 minutes under an argon stream with a hydrogen analyzer [Horiba Seisakusho EMGA621W] is determined, and the mass fraction is determined.

(5) Monochlorobenzene Extraction Amount According to JIS K6218: 1997, item 9 solvent extraction amount, monochlorobenzene as a solvent and extraction time for 30 hours were measured.

  As shown in Tables 4 and 5, Run No. having physicochemical properties. In order to evaluate the performance of the carbon blacks 1 to 9, rubber compositions were prepared at the blending ratios shown in Table 6 and the characteristic tests were performed. The results are shown in Tables 7-8.

Rubber properties were measured as follows.
(1) Rubber compounding method The rubber composition of the compounding ratio shown in Table 6 was kneaded using a Banbury mixer, and further vulcanized at 145 ° C. for 30 minutes with a pressure vulcanizer to obtain a vulcanized rubber.
(2) Evaluation of wear resistance of vulcanized rubber The amount of wear loss was measured using a Lambourn wear tester, and the wear resistance index was calculated from the following equation. In addition, it is excellent in abrasion resistance, so that a numerical value is large.
Wear resistance index = (S / T) x 100
Here, S: comparison reference (comparative example Run No. 8) test piece wear loss amount
T: Abrasion loss amount of each rubber test piece (3) Exothermic evaluation of vulcanized rubber The impact resilience was measured by the method described in JIS K6255: 1996. In addition, the measured value was displayed by the index | exponent with the impact resilience of the test piece of the comparative example (Run No. 8) as 100. The larger the index value, the higher the impact resilience and the lower the heat buildup.

  From the results of the physicochemical properties shown in Tables 4 and 5 and the rubber properties shown in Tables 7 and 8, the effects of the carbon black production process according to the present invention will be described. RunNo. The carbon blacks 1 to 4 are for the production process of the present invention. Carbon blacks 5-9 are comparative examples that deviate from one or more of the specific requirements of the present invention.

  RunNo. No. 5 is an example in which the value of β, which is one of the essential requirements of the production conditions of the present invention, exceeds the upper limit of 90.0. 1 but is inferior in Lambone wear resistance. 6 is an example in which β is below the lower limit of the calculated value. Although it approximates to 2, it is inferior in Lambourn abrasion resistance. In addition, RunNo. No. 7 is an example in which the values of α and β, which are one of the essential requirements of the production conditions of the present invention, are both below the lower limit of the range of the present invention. 2 but is inferior in Lambourne wear resistance. No. 8 is an example in which the value of α, which is one of the essential requirements of the production conditions of the present invention, exceeds the upper limit of the range of the present invention. Although it is close to 1, it is inferior in Lambourn abrasion resistance. Furthermore, RunNo. No. 9 is an example in which the values of α and β, which are one of the essential requirements of the production conditions of the present invention, exceeded the upper limit of the range of the present invention. 3 is inferior in terms of Lambourne wear resistance.

  From the rubber compounding characteristics shown in Tables 7 and 8, carbon black satisfying the production conditions disclosed in the examples is very good in wear resistance and low heat build-up (rebound resilience) as compared with the corresponding comparative examples. It can be seen that a high level is maintained even if it is evaluated as above. In particular, RunNo. 7 and 9 show a significant decrease in wear resistance.

It is longitudinal section explanatory drawing of the apparatus of an example of this invention. It is sectional drawing in the AA arrow of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Carbon black reaction apparatus 2 Flammable fluid introduction chamber 3 Oxygen-containing gas introduction pipe 4 Oxygen-containing gas introduction cylinder 5 Current plate 6 Fuel oil spraying apparatus introduction pipe 7 Converging chamber 8A Raw material oil spraying port 8B Raw material oil spraying port 8C Raw material oil Spray port 8D Raw material oil spray port 9 Raw material oil introduction chamber 10 Reaction continuation and quench chamber a to y Rapid water injection spray means

Claims (3)

Using a reactor in which a combustion zone, a reaction zone, and a reaction stop zone are connected coaxially, high-temperature combustion gas is generated by combustion of hydrocarbons for fuel in the combustion zone, and subsequently, in the high-temperature combustion gas stream in the reaction zone A raw material hydrocarbon is sprayed into the reaction gas stream containing carbon black converted from the raw material hydrocarbon by incomplete combustion or thermal decomposition reaction, and then the reaction gas stream is rapidly cooled in the reaction stop zone to complete the reaction. In the method for producing carbon black, the residence time from when the raw material hydrocarbon is introduced into the high-temperature gas stream to when the rapid refrigerant is introduced is defined as t ₁ (seconds), and the average reaction temperature in this space was a T _{1 (℃),} further quenching medium is introduced into the residence time of the reaction gas stream containing carbon black until said quench zone pass from t _{2 (seconds} The average reaction temperature in this space as T _{2 (°} C.), carbon black method of manufacturing and controlling under conditions satisfying the following (1) and (2) below.
(1) 2.00 ≦ α ≦ 9.00
(2) -2.5 × α + 85.0 ≦ β ≦ 90.0
(Wherein, α = t ₁ × T ₁ , β = t ₂ × T ₂ is represented) Α and β are (3) 3.00 ≦ α ≦ 8.00
(4) -2.5 × α + 85.0 ≦ β ≦ 86.0
The method for producing carbon black according to claim 1, wherein the control is performed under a condition satisfying the above range. Gas containing air or a mixture of oxygen and hydrocarbons or combustion gas from these combustion reactions in the space from the raw material hydrocarbon introduction position to the cooling medium introduction position and / or the space from the cooling medium introduction position to the reaction stop zone passage The method for producing carbon black according to claim 1 or 2, wherein a body is introduced and added.

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