JPH01278573A - Highly abrasion-resistant carbon black - Google Patents

Abstract

PURPOSE:To obtain the subject carbon black having a surface-active hydrogen ratio higher than a specific level and capable of imparting a compounded rubber with high abrasion resistance comparable or superior to class SAF carbon by reacting carbon black with sulfur under specific condition. CONSTITUTION:The objective carbon black having a surface-active hydrogen ratio of >=0.1 calculated from the amount of generated hydrogen sulfide by formula II [H2S(350) is amount of produced hydrogen sulfide gas at 350 deg.C] is produced by reacting (A) sulfur with (B) a carbon black having an aggregate size distribution index (S) of 0.10-0.15 calculated by formula I (Dst is the mode of the Stokes diameter of carbon black aggregate determined by centrifugal sedimentation analysis; D50L is Stokes diameter larger than Dst and having a mode corresponding to 1/2 of the mode of Dst), a nitrogen-adsorption specific surface area (N2SA) of 110-140m<2>/g determined in an inert atmosphere at 350-550 deg.C and a DBP absorption under pressure (24M4DBPA) of 80-120ml/100g.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a new furnace carbon black that is effective mainly for members requiring high wear resistance such as tire treads, and more specifically, This invention relates to a highly abrasion-resistant carbon black that can impart high abrasion resistance equivalent to or higher than SAF-grade carbon black to a compounded rubber, while having a lower specific surface area than SAF-grade carbon black.

[Prior Art] In rubber members such as tire treads that require particularly high wear resistance, SAF grade carbon black is blended with rubber and used.

Although conventional SAF grade carbon black has a large specific surface area (nitrogen adsorption specific surface area (NSA)) of 145rrr/g or more, it cannot be said that the wear resistance expected from the specific surface area is fully demonstrated. hard. Furthermore, when the specific surface area is increased to improve wear resistance, the hysteresis loss of the compounded rubber increases relatively, which in the case of automobile tires causes an increase in rolling resistance, which impedes the economical running of automobiles. Become. In addition, when using conventional technology to improve wear resistance by increasing specific surface area, heat generation occurs when carbon black and rubber are mixed, and viscosity increases during molding with an extruder. This was also an undesirable problem from the viewpoint of manufacturing rubber products.

[Problem to be solved by the invention] The present invention solves the above-mentioned drawbacks of conventional SAF grade carbon black, and provides wear resistance comparable to conventional SAF grade carbon black without increasing the surface area. It is an object of the present invention to provide a highly wear-resistant furnace carbon black that has at least the same or lower hysteresis loss and provides a rubber composition with improved processability.

[Means for solving the problem] The ability of carbon black to impart wear resistance to rubber is
Nitrogen adsorption specific surface area (N2SA) and l) B P oil absorption (
DBPA) or DBPA after compression (24M40BPA
) It is well known that it is largely related to the higher-order structure (structure I ~ structure).

However, according to recent findings, the ability of carbon black to impart wear resistance (reinforcing properties) to rubber can be significantly improved due to the narrow size distribution of aggregates (acrylates), which are the smallest dispersion unit of carbon black. A patent application has been filed (Applicant: Asahi Carbon Co., Ltd. JP-A-62-57433.62-57434).

The present inventors have found that the reinforcement property by narrowing the size distribution of Acryge-1 is also effective for carbon black of SAF grade or nearby varieties. By increasing the carbon black above a certain level, together with narrowing the acrylate size distribution, carbon black has a lower specific surface area than SAD grade carbon black, but has higher reinforcing properties than SAF grade carbon black. I found out that it can be obtained.

The Aggregation I size distribution index (S) is obtained by sedimentation analysis of carbon black, and the S of commercially available SAF grade carbon black is usually over 0.16, while the S is 0.16.
High reinforcing properties were achieved by narrowing the diameter to 15 or less, preferably 0.14 or less.

The surface activity of carbon black against matrix comb is generally recognized in relation to "active hydrogen" (Applicant: Prigistone Co., Ltd., JP-A-61-20
7542). There is also the idea of using the true specific gravity value of carbon black as a substitute characteristic for surface activity (Special Publications No. 53
-34149, JP-A-61-291636, JP-A-6L
-192468).

It is a pity that these indicators of ``surface activity'' include information other than the carbon black surface that is directly involved in reinforcing rubber.

That is, the hydrogen released from carbon black heated at a high temperature exceeding 1000° C. includes not only hydrogen present on the surface but also hydrogen released due to rearrangement of graphite-like microcrystals inside the carbon black particles. Furthermore, the true specific gravity value of carbon black reflects part of the information regarding the internal structure of carbon black particles, and is not considered to directly indicate the degree of surface activity.

The present inventors have discovered a new measuring method in which carbon black is directly reacted with sulfur at a relatively low temperature range, and the activity of the carbon black surface is determined by the amount of hydrogen sulfide gas generated. It has been found that the surface activity of carbon black greatly contributes to the reinforcing properties of rubber.

That is, in an inert gas atmosphere, a mixed powder of carbon black and sulfur was heated from room temperature at a rate of 10°C/m'n,
The amount of hydrogen sulfide gas generated at the time of reaching 350℃ and 550℃ is 11□5(350) and 1(2S(',), respectively.
50), the surface active hydrogen ratio (AHR) of carbon black is defined as follows.

A HR=++2S(350)/112S(550) Hydrogen on the surface of carbon black includes hydrogen that reacts with sulfur at relatively low temperatures and hydrogen that reacts at relatively high temperatures.
The present invention was completed based on the discovery that the higher the proportion of hydrogen that exhibits reactivity with sulfur in a low temperature range of 350° C. or lower, the higher the reactivity of carbon black with the comb, contributing to the reinforcing effect.

Normally commercially available S A, F class carbon black A HR
By satisfying the value of AHR to 0.1 and setting the value of AHR to 0.1 or more, preferably 0.15 or more, a carbon black with a higher reinforcing effect can be obtained.

The specific surface area of commercially available SAF grade carbon black is determined by the nitrogen adsorption method (BET method).
Generally, A) exceeds 145 m/g, but by setting the S and AHR to specified values, N25
It is possible to provide sufficient wear resistance even when A is 140 m/g or less.

In addition, by reducing N and SA to 140 m/g or less,
It is possible to lower hysteresis loss than ordinary SAF grade carbon black.

That is, the present invention has a nitrogen adsorption specific surface area (N2SA) of 110-1.40 rr? / g, compressed DBP oil absorption (24M4DI3PA) is 8080-12O/100g
For carbon black in the area of , the following calculation formula −
The acrylate size distribution index (S) obtained in ① is 0.
10 to 0.15, preferably 0.11 to 0.14, and at 350°C and 550°C under an inert atmosphere.
Surface active hydrogen amount ratio (AHR) calculated from the amount of hydrogen sulfide generated by reacting the carbon black and sulfur at a temperature of
) is 0.10 or more, preferably 0.12 or more.

Calculation formula-■: S = 0.84932XQog(D,'
. /Dst) Here, Dst is the most frequent value of the Stokes equivalent diameter of the carbon black aggregate determined by centrifugal sedimentation analysis, and Dko is on the larger side than Dst,
And it is a Stokes equivalent diameter having a frequency of 172 of Dst.

Other physicochemical properties of carbon black applied in the present invention are measured as follows.

(1) Nitrogen adsorption specific surface area (N2SA) Measured by ASTM D 3037-84B method and expressed as specific surface area i/g per unit weight.

(2) Compression D B P oil absorption (24M4 DBPA) A
It is measured according to STM D3493-84 and is expressed in mQ of dibutyl phthalate absorbed per 100 g.

(3) Carbon brass acrylate size analysis method using sedimentation analysis.

Equipment used Djsk Centrifuge Photo sed
imentometer (DCF) (English) Joyca
Measurement method manufactured by OEB1 Co., Ltd. 0.02 to 0.06% by weight of carbon black is added to a 30% methanol aqueous solution containing some surfactant and completely dispersed by ultrasonication. 15v/v
% glycerin aqueous solution sedimentation solution (spin solution) 20-30m
The number of revolutions of the rotating disk with Q separated is 80.
0 rpm, and separate 0.02 to 0.03 mQ of the above dispersion.

At the same time as dispersion liquid Ebetsu, a recorder is operated to optically measure the amount of carbon black aggregation 1 passing through a certain point near the outer periphery of the rotating disk due to sedimentation, and the amount is recorded as a histogram against time. do.

The sedimentation time is converted into a Stokes equivalent diameter using the following formula (general version of the Stokes formula) to obtain a histogram of Stokes equivalent diameters and their frequencies for carbon black aggregators 1 to 1.

d=-(1) t In formula (1), d is the Stokes equivalent diameter of the carbon black aggregate that passes through the optical measurement point of the rotating disk within a period of time after the start of sedimentation.

The constants include the amount of spin liquid at the time of measurement, viscosity, density difference with carbon black (true density of carbon black),
, 86 g/mQ), and is a constant determined by the rotation speed of the rotating disk. For example, using 25 ml (l) of a 15 S/V% glycerin aqueous solution as a spin liquid,
When the measurement temperature is 20° C. and the disk rotation speed is 800 rpm, the value is 492.3, where d is expressed in nm and d is expressed in minutes.

Definition of Dst and S The most frequent frequency in the Stokes equivalent diameter His 1-Cla 11 of the application obtained by the above measurement procedure (actually, it is the maximum absorbance because optical measurement is performed)
The equivalent diameter of the applicator that gives D st (M○de)
This is the standard for the average size of carbon black acrylate.

In addition, in the histogram, the frequency (
Ds
When the equivalent diameter of S1--x that is smaller than t is D3o, the acrylate size distribution index S is defined as 1-8=0.84932XQog (D:o/Dst). This is a measure of the distribution width of relatively large aggregator 1 sizes.

(4) AHR measurement method Approximately 100 μm of carbon fluff to be measured dried at 110° C. for 1 hour and approximately 10 μg of sulfur with a purity of 99% or more are mixed uniformly while being lightly ground in a mortar.

A mixture of carbon black and sulfur was placed in a quartz glass reaction tube (inner diameter 10+nn+, length 150 mm),
While maintaining the pressure in the reaction tube below 10 Torr with a vacuum pump, it was held at 90 to 100°C for 30 minutes in a tubular electric furnace. After cooling to room temperature, the reaction tube was filled with nitrogen gas, and then the reaction tube was filled with gas sampling rubber. Seal with a stopper. The reaction tube was heated at a temperature increase rate of 10°C/min in a tubular electric furnace, and when the temperature reached 350°C and 550°C, the gas sampling rubber stopper of the reaction tube was heated using a gas chroma 1-graph microsyringe. A certain amount of gas is sampled from the reaction tube, and the hydrogen sulfide concentration in the sampled gas is detected using a gas chroma 1-graph (manufactured by Shimadzu Corporation: G5-3BFP, column packing material: polyphenyl ether (Five Ringes), Instrument: Measure using FPD).

Letting the hydrogen sulfide concentrations at 350°C and 550°C be H7S (350) and u, 5 (550), respectively,
The surface active hydrogen ratio (AHR) of carbon black is calculated as follows.

A HR=H7S(350)/H2S(550) [Actual
Examples] Examples of the carbon black of the present invention are shown below to explain the present invention in more detail.

Manufacturing example A manufacturing example will be explained based on the attached drawings.

The attached FIG. 1 is a longitudinal sectional front view of an example of a production furnace used for producing carbon black of the present invention, FIG. 2 is a longitudinal sectional front view taken along arrow A-A in FIG. is B-
FIG.

Cylindrical combustion chamber 2 (inner diameter 325nwnφ, length 550mm
m), and a first raw oil inlet pipe 9 protected by a water cooling jacket 8 whose insertion position can be adjusted at the center of the upstream end of the combustion chamber (
Two first air introduction pipes 5.5' (inner diameter), ] 5 ninφ, having an inner diameter of 12,5 n+m) and a center located at a tangential position installed in the front half of the combustion chamber 2, also introduce fuel. possible) and six radial second fuel inlet pipes 6.6', 7.7 independent of said first inlet pipe.
', 7a, 7b (inner diameter 23nwnφ), and the narrowest part connected coaxially to the combustion chamber 2 with a diameter of 80mmφ and a length of 1
50nwn venturi part 3 and the venturi part 3
Four second feedstock oil inlet pipes (inner diameter 10 mmφ) 10.10 installed radially 80+nm downstream from the most upstream end of
', 11.11' and a reaction continuation/cooling chamber 4 (inner diameter 160+nmφ, length 2000 mm) coaxially connected to the venturi section 3, and the insertion position can be adjusted from the most downstream end of the reaction continuation/cooling chamber 4. cooling water inlet pipe] 2 (inner diameter 1
01TInφ) and a flue 13 connected at an angle of 90' to the rear end of the reaction continuation/cooling section 4, using a carbon black production furnace 1 entirely covered with a refractory,
Conditions for supplying air and fuel gas (liquefied petroleum gas) from the first and second introduction pipes, supply conditions for feed oil from the first and second feedstock oil introduction pipes, first feedstock oil introduction pipe The specific surface area can be changed by selecting the position of the tip and the position of the cooling water introduction pipe.
Furnace carbon blacks having different AHR1 compressed DBP oil absorption, Agric) Hesys distribution index (S) were produced.

The scratch structure of the produced carbon black was controlled by a commonly used method, that is, by appropriately adding alkali metals to the raw material oil.

The physicochemical properties of the raw material oil used are summarized in Table 1, and the production conditions and physicochemical properties of the obtained carbon black are summarized in Table 2. In addition, in order to evaluate the compounded rubber properties of the obtained carbon black, the rubber compounding conditions are listed below.
3, the properties of the 11 blends are summarized in Table 4.

(Space below) Table-1 Physical and chemical properties of raw material oil used (Space below) Table-3 Rubber compounding conditions (Space below) (Note) Comb property test conditions■ Vulcanization conditions for compound: 145℃, 30 minutes■ Resistance Abrasion test: Measurements are made using a Niranborn abrasion tester at slip rates of 25% and 60%, and the abrasion resistance is determined by the following formula.

Wear resistance index = (S/T)X100 (%) where S:
Volume loss at 25% and 60% slip ratio of IRBNα6 specimen.

T: Volume loss at 25% and 60% slip ratio of the test specimen.

■ Resilience test: Using a resilinine tester (newly manufactured by Toyo Seiki Seisakusho), B, S (ITrjtish 5t
andard) 903: Part A8: 196
Measure according to method A of 3.

■ Other rubber properties: JIS K 6300-19
74 and J], 'S K 6301-1975.

[Effects of the Invention Carbon blacks from Nα1 to No. 7 in Table 2 and Table 4 are carbon flats according to the present invention, and carbon blacks from Nα8 to No. ] and O are carbon blacks for performance comparison. be.

The carbon black with a low nitrogen specific surface area of Nα1 in the present invention is slightly inferior in wear resistance to other carbon blacks of the present invention with a high nitrogen specific surface area, but S is 0.15 on the high specific surface area side of the comparative example product. ” This is better than Nα9, which has two rotations. Further, as seen with Nα3 on the high specific surface area side of the present invention, although it is superior to No. 3 in terms of abrasion resistance, the rebound resilience tends to decrease slightly and the Mooney viscosity tends to increase. Therefore, it can be seen that in the present invention, it is preferable to set the nitrogen adsorption specific surface area to 110 to 1.40 r&/g.

Compression D B I) N of the present invention, which is low in oil absorption
Compared to Nα]- carbon black, L12 carbon black is inferior in high-severity abrasion resistance even if it has a high nitrogen adsorption specific surface area. It is necessary to do so. However, with the Nα4 carbon black on the high compression DBP oil absorption side of the present invention, wear resistance is improved, but
It is understood that the Mooney viscosity also increases. Therefore, in the present invention, the compressed DBP oil absorption amount is 80 to 120 u.
It can be seen that it is suitable to set Q/]OOg.

Even with carbon black that has a nitrogen adsorption specific surface area and compressed DBP oil absorption as described above, when S exceeds 0.15, the wear resistance decreases as seen in the performance comparison products of Na 9 and Na 10. It's inappropriate. In addition, as the S value decreases, there is a tendency for the rebound resilience to decrease as seen in the carbon black of Nα7 of the present invention. It is necessary to set it within the range of . Furthermore, as is clear from comparing the Nα5 and Nα7 of the present invention with the performance comparison product Nn 8, while the nitrogen adsorption specific surface area and compressed DBP oil absorption are at approximately the same level, the surface active hydrogen amount ratio AHR is decreased. Then, it is recognized that the wear resistance decreases, and in the present invention, the AHR is at least -21=0. ] Must be set to 0 or more, preferably 0
．． It can be seen that a value of 12 or more is suitable.

Furthermore, when comparing the Nα6 and No. 5 carbon blacks of the present invention, both have almost the same properties other than the AHR value, but the N[16 carbon black has a higher AHR than No. 5. Since the value of AH is low, the wear resistance tends to decrease, and in the present invention, AH
It can be seen that it is preferable to set the R value to a high value of 0.10 or more.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view of an example production furnace used for producing carbon black of the present invention, FIG. 2 is a longitudinal sectional front view of the production furnace in FIG. is B-B
FIG. 2. Combustion chamber 4 Reaction continuation/cooling chamber 5.5'
Air introduction pipe 6.6', 7.7' Fuel introduction pipe 9 Raw material oil introduction pipe 10.10', 11. II' Raw oil inlet pipe 13・
- Flue patent applicant Kan Carbon Co., Ltd. agent Patent attorney Sa 1) Mamoru A and 2 others - 24 =

Claims (1)

[Claims] 1. Nitrogen adsorption specific surface area (N_2SA) is 110 to 140
m^2/g, compressed DBP oil absorption (24M4DBPA) is in the range of 80 to 120 ml/100 g, and the acrylate size distribution index (S) obtained from the following calculation formula - [1] is 0.10 to 120 ml/100 g. 0.15 and 350°C and 550°C under an inert atmosphere
A highly wear-resistant carbon having a surface active hydrogen ratio (AHR) of 0.10 or more, which is calculated from the amount of hydrogen sulfide generated by reacting the carbon black with sulfur at a temperature of black. Calculation formula - [1]: S = 0.84932 x log (D^L
_5_0/Dst) Here, Dst is the most frequent value of the Stokes equivalent diameter of carbon black acrylate determined by centrifugal sedimentation analysis, and D^L_5_0 is on the larger side than Dst and has a frequency of 1/2 of Dst. It has a Stokes equivalent diameter. Calculation formula - [2]: AHR=H_2S(350)/H_2
S(500) Here, H_2S(350) is the amount of hydrogen sulfide gas produced when the temperature reaches 350°C, and H_2S(5
00) is the amount of hydrogen sulfide gas at 500°C.