JPH01136A - rubber composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rubber composition that has excellent carbon black dispersion processability and has performance suitable for use in tire treads.

[Conventional technology]

There are various types of carbon black for rubber reinforcement depending on the characteristics, and the characteristics of these types are the main factors that determine the various performances of the rubber composition to be blended. For this reason, when blending with the rubber component, a carbon black whose variety characteristics are suitable for the component use is usually selected and used.

For example, for rubber parts such as tire treads that require a high degree of wear resistance under harsh driving conditions,
Hard carbon blacks such as iAF (NIIO) and l5AF (N220) are used.

However, these carbon blacks have small particle sizes,
Due to the large specific surface area, the rubber component becomes highly viscous and hard during the kneading process during rubber compounding, making it difficult to homogeneously disperse it into the rubber component. As a result, the quality characteristics of the compounded rubber deteriorate, resulting in, for example, a decrease in abrasion resistance.

Therefore, a rubber composition with improved wear resistance has been proposed by improving the dispersion processability of carbon black into the rubber component. For example, the present applicant focused on particle aggregates of carbon black and blended carbon black with a broad aggregate size distribution (patent application filed in 1983).
1-256944) or a rubber composition blended with carbon black having two maximum points in a specific range of aggregate size distribution (Japanese Patent Application No. 62-9956) ◇ [Problems to be Solved by the Invention] ] As a result of further research into the relationship between carbon black particle aggregates and dispersion processability, the present invention was developed by setting the voids of particle aggregates relatively large per a certain specific surface area of carbon black, thereby making it possible to improve the relationship between the rubber component and the dispersion processability. This was completed after discovering the fact that the dispersion processability in the crosstalk process can be improved.

[Means for solving problems]

That is, the present invention belongs to the hard region where the nitrogen adsorption specific surface area (NSA) is 140 m'/g or more, and the particle aggregate pore diameter (nm) is 59.182-0.236X (N, 5
Carbon black having a characteristic value higher than the value calculated by the formula
It is a rubber composition formed by blending the compound in a proportion of 5 to 100 parts by weight.

Carbon black with a nitrogen adsorption specific surface area (NSA) of 140 m"7g or more corresponds to carbon black with a small particle size of 5AF (NIIO) or more, and is highly recommended as a rubber composition used as a tire tread. This is an essential requirement for imparting wear resistance.

The rubber composition of the present invention is based on the carbon black having a large specific surface area, and the carbon black particle aggregate pore diameter (nm) is 59.182-0.236X (N, 5A
(1''/9) Carbon black having a characteristic value greater than the value calculated from equation 3 is blended into the rubber component.

Carbon black is produced by rapidly pyrolyzing a hydrocarbon feedstock in a stream of hot combustion gases. In this case, the hydrocarbon raw material first generates nuclei through a complex polycondensation reaction, and primary particles are formed by the growth and aggregation of these nuclei.
Furthermore, a large number of primary particles aggregate to form a carbon black particle aggregate structure.

These particle aggregates exhibit a three-dimensional complex morphology, and the aggregate morphology does not change even during the kneading process with the rubber component. In order to improve dispersion processability, it is important to easily and sufficiently infiltrate the voids formed between the aggregates.

However, the nitrogen adsorption specific surface area (NSA) was 14011
Conventional types of carbon black with a particle diameter of more than 1.5%/g have structurally small voids in particle aggregates, so it has been considered extremely difficult to improve the dispersion processability of rubber in terms of carbon black properties.

The carbon black applied to the present invention has a basic structure with two maximum points in the aggregate Stokes mode diameter distribution, and by utilizing this unique property, it can be used in a high nitrogen adsorption specific surface area (N2SA) region. This is intended to improve dispersion processability.

Therefore, it is virtually impossible to provide the particle aggregate voids of the present invention with carbon black having a conventional structure exhibiting an aggregate Stokes mode diameter distribution with a single maximum point.

The particle aggregate voids of the present invention are characterized by being relatively large when the specific surface area is constant.

The particle aggregate pore diameter is measured as follows.

That is, using a mercury porosimeter (Pore 5izer 9300) manufactured by Micromeritic, 0.29 carbon black pellets prepared to a particle size of 250 to 500μ were loaded into a special cell (331C), and then the pressure was set to 25 to 2000 lb/in. Mercury is injected within the range of , and the pressure at the point where the amount of mercury injected rapidly increases is measured.The pore diameter is calculated from the pressure, and this is taken as the particle aggregate pore diameter.

Using this measurement method, IRB #5 (N2S A 80
, 3g'/9), the particle aggregate pore diameter was 40 nm.

Carbon black with these characteristics is produced by installing two generation sections each consisting of a combustion chamber equipped with a combustion burner and a feedstock oil injection nozzle at the head, and a pyrolysis conduit connected to the combustion chamber. Using an oil furnace with a figure-7 structure in which pyrolysis conduits are convergently assembled in a cylindrical main reaction zone, carbon black intermediate gas flows generated in both series are simultaneously introduced at high speed into the main reaction zone and collided with each other. It can be manufactured by the method (Japanese Patent Application Laid-Open No. 59-49267).

The above carbon black is blended into natural rubber and various synthetic rubbers according to conventional methods. The blending ratio of carbon black is 35 to 100 parts by weight of the rubber component! The rubber composition of the present invention is obtained by mixing the rubber composition with a vulcanizing agent, a vulcanization accelerator, an anti-aging agent, a vulcanization aid, a softener, a plasticizer and the like.

[For production]

The rubber composition of the present invention targets carbon black with a large specific surface area and high reinforcing properties, and has a composition in which carbon black with relatively large particle aggregate voids per certain specific surface area is blended. During the blending and kneading process with the rubber component, the rubber component can easily penetrate into the voids between the carbon black particle aggregates, resulting in a marked improvement in dispersion processability. Therefore, it is possible to effectively prevent the abrasion resistance of the rubber composition from deteriorating due to a decrease in dispersibility.

[Example, comparative example]

Combustion chamber (inner diameter 550mm) with combustion burner and raw material injection nozzle coaxially attached to the head via a wind box
, length 1100vx, of which the conical part 200zx) and pyrolysis groove W (inner diameter 90cm, length 700xm) were made into two series of generation parts with an inner diameter of 300m and a length of 4000zi.
A reactor with a Y-shaped structure was installed in front of the main reaction zone, in which a rear wide-diameter part and a front narrow-diameter part with an inner diameter of 130 xi and a length of 700 mm were connected in series, and the reactor was convergently coupled at an intersection angle of 60°.

The raw material oil has a specific gravity (15/4°C) of 1.0703, a viscosity (Engler-40/20°C) of 2.10, and a toluene insoluble content of 0.
03%, correlation coefficient (BMCI) 140, initial boiling point 1
Aromatic hydrocarbon oil at 03°C, and fuel oil with specific gravity (15/4°C) 0.903 and viscosity (50°C) 16, l
cSt, residual content 5.4%, sulfur content 1.8%, flash point 9
Hydrocarbon oil at 6°C was used.

Using this reactor, raw material oil, and fuel oil, and applying the generation conditions shown in Table I, carbon black having the characteristic range used in the present invention was produced.

Table 2 Table 2 shows the nitrogen adsorption specific surface area (N, 5A), DBP oil absorption, particle aggregate pore diameter, etc. of each carbon black produced.

Table ■ RunN0°3-5 shown as a comparative example in Table H
These are carbon blacks having nitrogen adsorption specific surface areas (NtsA) at the same level as those of the examples produced by the conventional technology, and both exhibit aggregate Stokes mode diameter distributions with a single maximum point.

Next, the various carbon blacks shown in Table 1 were blended with natural rubber at the blending ratios shown in Table 2.

Table 2 Rubber properties of a rubber composition obtained by vulcanizing the compound in Table 2 at a temperature of 145° C. for 40 minutes were measured, and the results are shown in Table 2 in correspondence with the carbon black Run No. in Table I.

Among the rubber properties, the amount of wear was measured using a Lambourn abrasion tester (mechanical slip mechanism) under the following conditions.

Test piece: Thickness 10 mm, outer diameter 44 mm emery wheel 2 GC type, particle size #80, hardness I] Added carporundum powder: particle size #80 mesh, added claw approx. 99/min Relative slip rate between emery wheel surface and test piece ;24
% Test piece rotation speed: 660 rpm Test load: 4 to 9 Other rubber properties were in accordance with JIS K6300 r "Physical test method for unvulcanized rubber" and JISI (6301 "Physical test method for vulcanized rubber").

From the results in Table ■ Table ■, the rubber compositions of the examples have a low Mooney viscosity, which is an index of dispersion processability, with respect to the level of nitrogen adsorption specific surface area (NSA), and also have excellent wear resistance. becomes clear.

〔Effect of the invention〕

The rubber composition of the present invention has good dispersion processability and a high degree of abrasion resistance, making it extremely useful for tire treads.

Patent applicant: Tokai Carbon Co., Ltd. Agent: Patent Attorney Masaya Takahata

Claims (1)

[Claims] 1. Nitrogen adsorption specific surface area (N_2SA) is 140 m^2/
Belongs to the hard region of particle aggregate pore diameter (nm
) is 59.182-0.236×[N_2SA(m^
2/g)] 35 to 10 parts of carbon black having a characteristic value higher than the value calculated by the formula for 100 parts by weight of the rubber component.
A rubber composition containing 0 parts by weight.