JP2001226610A - Carbon black and rubber composition containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon black capable of giving a compound rubber high abrasion resistance, and to obtain a rubber composition having high abrasion resistance by compounding the carbon black. SOLUTION: This carbon black is characterized by having selective characteristics satisfying the following relationships (1) and (2): B>135...(1) and B>=-8.4×Dp+284...(2) (wherein, B is blackness (%); and Dp is aggregate void diameter (nm) determined by the mercury press-in method. The other objective rubber composition is obtained by compounding 25-200 pts.wt. of the above carbon black in 100 pts.wt. of natural rubber, a synthetic rubber or a blend rubber thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a carbon black capable of imparting a high degree of wear resistance to a compounded rubber, and a rubber composition containing the carbon black.

[0002]

2. Description of the Related Art There are various types of carbon blacks for reinforcing rubber according to their characteristics, and the characteristics of these types are major factors for determining various properties of a composition mixed with rubber. For this reason, when compounding with rubber, means for selecting and using carbon black having a variety of characteristics suitable for the application of the member is usually used.

[0003] For example, SAF (N11) is used for rubber members such as tire treads which require a high degree of wear resistance.
0), hard carbon black having a small particle diameter such as ISAF (N220) is applied. However, the abrasion resistance of the rubber composition can be improved as the particle diameter of the compounded carbon black is smaller and the specific surface area is larger, but on the other hand, other rubber physical properties, such as increased heat buildup, are disadvantageous. There is.

[0004] Therefore, in addition to the characteristic factors such as particle diameter, specific surface area, and structure that have been conventionally regarded as the basic characteristics of carbon black for rubber reinforcement, the aggregation form of carbon black particles and the physicochemical properties of the particle surface Attempts have been actively made to improve the properties of carbon black compounded rubber by selectively imparting microscopic properties such as those described in, for example, JP-A-3-50249.
3-121165, 4-209640, etc.).

On the other hand, carbon black having a small particle diameter and a large specific surface area is liable to agglomerate during the kneading process when compounded with the rubber component. It is extremely difficult to uniformly disperse in a microscopic state. As a result, the effect of improving the wear resistance was not always sufficient.

Therefore, the applicant of the present invention has a rubber composition having excellent dispersibility and high abrasion resistance, which belongs to a hard region having a nitrogen adsorption specific surface area (N ₂ SA) of 140 m ² / g or more,
The particle aggregate void diameter (nm) is 59.182-0.236
× [N ₂ SA] carbon black having a characteristic value equal to or more than the value calculated by the formula is 35 to 100 parts by weight of the rubber component.
Rubber composition blended in a proportion of 100 parts by weight
No. 64-136).

[0007]

The present inventor further studied the relationship between the characteristics of carbon black and the abrasion resistance of the compounded rubber by focusing on the form of dispersion of the carbon black in the compounded rubber. It has been found that the three-dimensional network structure formed by carbon black in the rubber composition is closely related to the wear resistance of the rubber composition.

The present invention has been developed on the basis of this finding, and its object is to provide carbon black capable of imparting a high degree of abrasion resistance to a compounded rubber, particularly in a low slip region. Another object of the present invention is to provide a rubber composition having a high degree of abrasion resistance containing the carbon black.

[0009]

Means for Solving the Problems The carbon black of the present invention for achieving the above object has a structural characteristic that the carbon black has selective characteristics satisfying the relationship of the following formulas (1) and (2). I do. B> 135 (1) B ≧ −8.4 × Dp + 284 (2) where B is blackness (%), and Dp is an aggregate void diameter (nm) measured by a mercury intrusion method.

The rubber composition of the present invention comprises a natural rubber,
It is characterized in that 25 to 200 parts by weight of the above carbon black is blended with 100 parts by weight of synthetic rubber or a blend rubber thereof.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The blackness B of carbon black has long been used as an index indicating the blackness of carbon black, and is affected by the particle size, specific surface area, size of aggregates, etc. of carbon black. . Therefore, the blackness B can be regarded as a comprehensive characteristic element including many colloidal properties including the particle properties of carbon black, and is measured by the following method.

Measurement method for blackness B; particle size 149 μm
A 0.500 g sample of the following dried carbon black was sampled, kneaded sufficiently while dripping linseed oil on a glass plate, then transferred to a Hoover maller, and kneaded 25 times with a load of 15 pounds on the Hoover maller five times. Repeat to prepare paste. A small amount of this paste is placed on a glass plate, and a thin film is formed using a doctor blade. A dencyclon reflectometer (Sargent Welch Scientific) was formed on a thin film similarly formed in advance for the reference sample IRB # 2.
(Manufactured by the company) and set it to 50%, and the meter value when moving the head at least three places is 49.5 to 59.5.
Confirm that it becomes 50.5%. Next, a head is placed on the thin film of the carbon black sample to read five values, and the average value is set as T to calculate the value of the blackness B by the following equation. B (%) = (50 / T) × 100

As described above, since the blackness B is measured in a state of being kneaded and dispersed in linseed oil, its value is a comprehensive characteristic element including colloidal properties such as the particle properties of carbon black and the dispersion state. Will be affected. That is, the measured value of blackness B is
It can be considered as a property measured in a state close to a three-dimensional network structure of carbon black dispersed in rubber.

In the carbon black of the present invention, the first
The reason why the value of the blackness B is set to a value exceeding 135 as a characteristic requirement is that it is a premise that the wear resistance is secured. If the value of B is 135 or less, the wear resistance decreases.

Furthermore, the carbon black of the present invention is
The characteristic requirement of (2) is that the value of blackness B is related to the aggregate void diameter Dp (nm) of carbon black.
It is necessary to satisfy the relationship of the expression, that is, the relationship of B ≧ −8.4 × Dp + 284.

The aggregate void diameter Dp (nm) is a value measured by the following method. After loading 0.2 g of carbon black pellets adjusted to a particle size of 250 to 500 μm into a dedicated cell (3 ml) of a mercury porosimeter (Pore Sizer 9300 manufactured by Micromeritics Co., Ltd.),
Mercury is injected in the range of 5-2000 lb / in ² and the pressure at which the amount of injected mercury sharply increases is measured. The aggregate pore diameter (nm) of carbon black is calculated from this pressure value.

The aggregate void diameter Dp measured by the above method is an index indicating the size of the three-dimensional network structure in which the carbon black particles are fused and bonded. Relation, B ≧ −8.4 × Dp + 28
4, that is, when the value of the blackness B is relatively large with respect to the constant aggregate void diameter Dp, the voids formed by the carbon black three-dimensional network structure in the compounded rubber become complex and uniform, Works to improve wear resistance.

As described above, the carbon black of the present invention is characterized in that the value of blackness B is large and the value of blackness B is relatively large with respect to a constant aggregate void diameter Dp. Function synergistically to impart high abrasion resistance to the compounded rubber.

The rubber composition of the present invention is obtained by adding the carbon black of the present invention having the above-mentioned properties to natural rubber and styrene-
Butadiene rubber, butadiene rubber, isoprene rubber, chloroprene rubber, ethylene-propylene-diene copolymer rubber, butyl rubber, acrylonitrile rubber, various synthetic rubbers that can be reinforced with conventional carbon black, or blended rubbers obtained by mixing them, etc. Rubber component 100
It is blended at a ratio of 25 to 200 parts by weight with respect to parts by weight. If the compounding ratio of carbon black is less than 25 parts by weight, a sufficient reinforcing effect cannot be obtained, and a high degree of wear resistance cannot be imparted. On the other hand, if it exceeds 200 parts by weight, the viscosity increases during compounding and kneading with the rubber component, and the processability is significantly reduced. In addition, at the time of compounding with a rubber component, a rubber composition is obtained by kneading with necessary components such as a usual vulcanizing agent, a vulcanization accelerator, an antioxidant, a vulcanization aid, a softener, and a plasticizer.

The carbon black of the present invention is obtained by using a cylindrical reactor having a drum-shaped throttle portion that gradually converges and opens, and converts the raw material oil into a high-temperature combustion gas containing a fuel oil and an appropriate oxidant containing air or nitrogen. It is produced by introducing an atomizing gas stream in two stages. High aromatic heavy oils such as creosote oil, ethylene bottom oil, and FCC oil are used as feedstock oils.
In order to obtain a high-quality homogeneous mixed state with the high-temperature combustion gas, it is introduced as a sufficient fine particle stream through an atomizing injection nozzle.
The atomization injection nozzle has, for example, a double structure having a water-cooled outer cylinder and an outer cylinder nozzle that can be extended and contracted in the furnace axis direction and an extendable middle cylinder nozzle that is attached to the nozzle. Separately attached to the furnace head. The base oil is introduced in two stages through the outer cylinder nozzle and the center cylinder nozzle together with the atomized gas, but the position of the base oil introduction at this time can be changed by the advance / retreat of the outer cylinder nozzle and the expansion / contraction of the center nozzle. .
The carbon black of the present invention, the amount of air supplied using the above device, the amount of nitrogen and the amount of fuel oil, the split introduction point of the feedstock,
It can be produced by controlling the residence time of the produced carbon black in the furnace.

[0021]

Hereinafter, examples of the present invention will be described in comparison with comparative examples.

Examples 1 to 4 and Comparative Examples 1 to 6 (1) Production of carbon black A wind box provided with a tangential air supply port at the furnace head and a combustion chamber (inner diameter 400 mm,
An oil consisting of a narrow-diameter part (inner diameter 200 mm, length 200 mm) coaxially connected to the combustion chamber and a tapered reaction chamber (inner diameter 500 mm, length 9000 mm) that opens subsequently to this oil In the furnace, a double-cylindrical feedstock atomizing spray nozzle was installed from the furnace head along the furnace center axis, and four combustion burners were installed around the nozzle. The material injection nozzle is located at the upstream material introduction point (outlet of the outer cylinder nozzle)
Was adjusted to be located at the convergent site, and the downstream raw material introduction point was located at the narrow diameter site.

The oil furnace has a specific gravity (15/4 ° C.) of 1.127 and a toluene-insoluble content of 0.05 with respect to the raw material oil.
%, Correlation coefficient (BMCI) 159, aromatic hydrocarbon oil having an initial boiling point of 218 ° C, and specific gravity (15/4 ° C) 1.02 for fuel oil
7. Toluene insoluble content 0.01%, correlation coefficient (BMCI) 11
1. Using a hydrocarbon oil having an initial boiling point of 136 ° C., carbon black having different properties was produced by changing the reaction conditions. Table 1 shows the applied manufacturing conditions and the characteristics of the obtained carbon black.
It was shown to.

[0024]

[Table 1]

(2) Preparation of Rubber Composition These carbon blacks were blended with natural rubber at the blending ratio shown in Table 2, and the blend was vulcanized at a temperature of 145 ° C. for 30 minutes to prepare a rubber composition.

[0026]

[Table 2]

(3) Rubber Property Test The amount of abrasion was measured for each of the produced rubber compositions using a Lambourn abrasion tester (mechanical slip mechanism) under the following conditions, and the obtained results are also shown in Table 1. . FIG. 1 shows the relationship between the blackness B and the wear amount. Test piece: thickness 10mm, outer diameter 44mm Emery wheel: GC type, particle size # 80, hardness H Carburundum powder with addition: particle size # 80, addition amount about 9g / mi
n. Relative slip ratio between emery wheel surface and test piece: 24% Test piece rotation speed: 535 rpm Test load: 4 kg

From the results shown in Table 1 and FIG. 1, the rubber compositions containing the carbon blacks of Examples 1 to 4 are comparative examples 1 to 4.
It can be seen that the abrasion amount is small and the abrasion resistance is excellent as compared with the rubber composition containing carbon black of No. 6. That is, the values of the blackness B, Comparative Examples 4 to 5 in which carbon black not satisfying the requirement of B> 135 were blended
All of the rubber compositions of No. 6 have a large amount of wear, and B ≧
Even if the requirement of −8.4 × Dp + 284 is satisfied (Comparative Example 4
And 6) It can be seen that the wear resistance is low. Further, B>
Even if the requirement of 135 is satisfied, B ≧ −8.4 × Dp +
It is recognized that the rubber compositions of Comparative Examples 1 to 3 which do not satisfy the requirement of No. 284 have a larger abrasion amount than those of Examples 1 to 4 having the same B value and are inferior in abrasion resistance.

[0029]

As described above, the values of blackness B and aggregate void diameter Dp specified in the present invention are B> 135.
(1) and B ≧ −8.4 × Dp + 284 (2) By using a carbon black satisfying the relationship of the formula,
High abrasion resistance can be imparted to the compounded rubber, and a rubber composition having high abrasion resistance can be provided.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between blackness B and a wear amount according to an example and a comparative example.

Claims (2)

[Claims] 1. A carbon black having selective characteristics satisfying the relationship of the following formulas (1) and (2). B> 135 (1) B ≧ −8.4 × Dp + 284 (2) where B is blackness (%), and Dp is an aggregate void diameter (nm) measured by a mercury intrusion method. 2. A rubber composition obtained by blending 25 to 200 parts by weight of the carbon black according to claim 1 with 100 parts by weight of natural rubber, synthetic rubber, or a blended rubber thereof.